page 26 of 30
MIAPbP
(440)Revisiting longitudinal plasmon-axion conversion in external magnetic fields
  • Andrea Caputo,
  • Alexander J. Millar,
  • Edoardo Vitagliano
Physical Review D (06/2020) doi:10.1103/PhysRevD.101.123004
abstract + abstract -

In the presence of an external magnetic field, the axion and the photon mix. In particular, the dispersion relation of a longitudinal plasmon always crosses the dispersion relation of the axion (for small axion masses), thus leading to a resonant conversion. Using thermal field theory, we concisely derive the axion emission rate, applying it to astrophysical and laboratory scenarios. For the Sun, depending on the magnetic field profile, plasmon-axion conversion can dominate over Primakoff production at low energies (≲200 eV ). This both provides a new axion source for future helioscopes and, in the event of discovery, would probe the magnetic field structure of the Sun. In the case of white dwarfs (WDs), plasmon-axion conversion provides a pure photon coupling probe of the axion, which may contribute significantly for low-mass WDs. Finally, we rederive and confirm the axion absorption rate of the recently proposed plasma haloscopes.


(439)Galaxy formation in the brane world I: overview and first results
  • César Hernández-Aguayo,
  • Christian Arnold,
  • Baojiu Li,
  • Carlton M. Baugh
Mon.Not.Roy.Astron.Soc. (06/2020) e-Print:2006.15467 doi:10.1093/mnras/stab694
abstract + abstract -

We carry out ‘full-physics’ hydrodynamical simulations of galaxy formation in the normal-branch Dvali–Gabadadze–Porrati (nDGP) braneworld model using a new modified version of the arepo code and the IllustrisTNG galaxy formation model. We simulate two nDGP models (N5 and N1) that represent, respectively, weak and moderate departures from general relativity (GR), in boxes of sizes |$62$| and |$25\, h^{-1}{\rm Mpc}$| using 2 × 512^3 dark matter particles and initial gas cells. This allows us to explore, for the first time, the impact of baryonic physics on galactic scales in braneworld models of modified gravity and to make predictions on the stellar content of dark matter haloes and galaxy evolution through cosmic time in these models. We find significant differences between the GR and nDGP models in the power spectra and correlation functions of gas, stars and dark matter of up to ∼25 per cent on large scales. Similar to their impact in the standard cosmological model (Λ cold dark matter), baryonic effects can have a significant influence over the clustering of the overall matter distribution, with a sign that depends on scale. Studying the degeneracy between modified gravity and galactic feedback in these models, we find that these two physical effects on matter clustering can be cleanly disentangled, allowing for a method to accurately predict the matter power spectrum with baryonic effects included, without having to run hydrodynamical simulations. Depending on the braneworld model, we find differences compared with GR of up to ∼15 per cent in galaxy properties such as the stellar-to-halo-mass ratio, galaxy stellar mass function, gas fraction, and star formation rate density. The amplitude of the fifth force is reduced by the presence of baryons in the very inner part of haloes, but this reduction quickly becomes negligible above ∼0.1 times the halo radius.


MIAPbP
(438)Black Hole Superradiant Instability from Ultralight Spin-2 Fields
  • Richard Brito,
  • Sara Grillo,
  • Paolo Pani
Physical Review Letters (05/2020) doi:10.1103/PhysRevLett.124.211101
abstract + abstract -

Ultralight bosonic fields are compelling dark-matter candidates and arise in a variety of beyond standard model scenarios. These fields can tap energy and angular momentum from spinning black holes through superradiant instabilities, during which a macroscopic bosonic condensate develops around the black hole. Striking features of this phenomenon include gaps in the spin-mass distribution of astrophysical black holes and a continuous gravitational-wave (GW) signal emitted by the condensate. So far these processes have been studied in great detail for scalar fields and, more recently, for vector fields. Here we take an important step forward in the black hole superradiance program by computing, analytically, the instability timescale, direct GW emission, and stochastic background, in the case of massive tensor (i.e., spin-2) fields. Our analysis is valid for any black hole spin and for small boson masses. The instability of massive spin-2 fields shares some properties with the scalar and vector cases, but its phenomenology is much richer, for example, there exist multiple modes with comparable instability timescales, and the dominant GW signal is hexadecapolar rather than quadrupolar. Electromagnetic and GW observations of spinning black holes in the mass range M ∈(1 ,1010) M can constrain the mass of a putative spin-2 field in the range 10-22≲mb c2/eV ≲10-10 . For 10-17≲mb c2/eV ≲10-15 , the space mission LISA could detect the continuous GW signal for sources at redshift z =20 , or even larger.


(437)Building a digital twin of a luminous red galaxy spectroscopic survey: galaxy properties and clustering covariance
  • César Hernández-Aguayo,
  • Francisco Prada,
  • Carlton M. Baugh,
  • Anatoly Klypin
Mon.Not.Roy.Astron.Soc. (05/2020) e-Print:2006.00612 doi:10.1093/mnras/stab434
abstract + abstract -

Upcoming surveys will use a variety of galaxy selections to map the large-scale structure of the Universe. It is important to make accurate predictions for the properties and clustering of such galaxies, including the errors on these statistics. Here, we describe a novel technique which uses the semi-analytical model of galaxy formation galform, embedded in the high-resolution N-body Planck-Millennium simulation, to populate a thousand halo catalogues generated using the Parallel-PM N-body glam code. Our hybrid scheme allows us to make clustering predictions on scales that cannot be modelled in the original N-body simulation. We focus on luminous red galaxies (LRGs) selected in the redshift range z = 0.6 − 1 from the galform output using similar colour-magnitude cuts in the r, z, and W1 bands to those that will be applied in the Dark Energy Spectroscopic Instrument (DESI) survey, and call this illustrative sample ‘DESI-like’ LRGs. We find that the LRG-halo connection is non-trivial, leading to the prediction of a non-standard halo occupation distribution; in particular, the occupation of central galaxies does not reach unity for the most massive haloes, and drops with increasing mass. The glam catalogues reproduce the abundance and clustering of the LRGs predicted by galform. We use the glam mocks to compute the covariance matrices for the two-point correlation function and power spectrum of the LRGs and their background dark matter density field, revealing important differences. We also make predictions for the linear-growth rate and the baryon acoustic oscillations distances at z = 0.6, 0.74, and 0.93. All ‘DESI-like’ LRG catalogues are made publicly available.


MIAPbP
(436)Generalized BMS charge algebra
  • Miguel Campiglia,
  • Javier Peraza
Physical Review D (05/2020) doi:10.1103/PhysRevD.101.104039
abstract + abstract -

It has been argued that the symmetries of gravity at null infinity should include a Diff (S2) factor associated with diffeomorphisms on the celestial sphere. However, the standard phase space of gravity does not support the action of such transformations. Building on earlier work by Laddha and one of the authors, we present an extension of the phase space of gravity at null infinity on which Diff (S2) acts canonically. The Poisson brackets of supertranslation and Diff (S2) charges reproduce the generalized BMS algebra introduced in [Campiglia and Laddha Phys. Rev. D 90, 124028 (2014), 10.1103/PhysRevD.90.124028].


MIAPbP
(435)Understanding the Fundamental Plane and the Tully Fisher Relation
  • Jeremy Mould
Frontiers in Astronomy and Space Sciences (05/2020) doi:10.3389/fspas.2020.00021
abstract + abstract -

The relation between early type galaxy size, surface brightness and velocity dispersion, ``the fundamental plane", has long been understood as resulting from equilibrium in their largely pressure supported stellar dynamics. The dissipation and feedback involved in reaching such an equilibrium through merger formation of these galaxies over cosmic time can be responsible for the orientation of the plane. We see a correlation between surface brightness enhancement and youth in the 6dF Galaxy Survey. Correlations of this `tilt' with stellar mass, age, concentration, shape and metallicity now point the direction for further work on the resolved kinematics and structure of these nearby galaxies and on their initial mass function and dark matter component. On the face of it, the Tully Fisher relation is a simpler one dimensional scaling relation. However, as late type galaxies have bulges as well as disks, and, as the surface density of disks is only standard for the more massive galaxies, additional parameters are involved.


MIAPbP
(434)Testing the origin of the "f<SUB>1</SUB>(1420 ) " with the K ¯ p →Λ (Σ )K K ¯ π reaction
  • Wei-Hong Liang,
  • E. Oset
European Physical Journal C (05/2020) doi:10.1140/epjc/s10052-020-7966-y
abstract + abstract -

We study the K ¯ p →Y K K ¯ π reactions with K ¯ =K¯ 0,K- and Y =Σ0+,Λ , in the region of K K ¯ π invariant masses of 1200 -1550 MeV. The strong coupling of the f1(1285 ) resonance to KK ¯ makes the mechanism based on K exchange very efficient to produce this resonance observed in the K K ¯ π invariant mass distribution. In addition, in all these reactions one observes an associated peak at 1420 MeV which comes from the KK ¯ decay mode of the f1(1285 ) when the K is placed on shell at higher invariant masses. We call the attention to the possibility that the peaks observed in other reactions where the "f1(1420 ) " is observed have a similar origin.


(433)Cosmology dependence of galaxy cluster scaling relations
  • Priyanka Singh,
  • Alex Saro,
  • Matteo Costanzi,
  • Klaus Dolag
Monthly Notices of the Royal Astronomical Society (05/2020) doi:10.1093/mnras/staa1004
abstract + abstract -

The abundance of galaxy clusters as a function of mass and redshift is a well known powerful cosmological probe, which relies on underlying modelling assumptions on the mass-observable relations (MOR). Some of the MOR parameters can be constrained directly from multi-wavelength observations, as the normalization at some reference cosmology, the mass-slope, the redshift evolution, and the intrinsic scatter. However, the cosmology dependence of MORs cannot be tested with multi-wavelength observations alone. We use magneticum simulations to explore the cosmology dependence of galaxy cluster scaling relations. We run fifteen hydrodynamical cosmological simulations varying Ωm, Ωb, h0, and σ8 (around a reference cosmological model). The MORs considered are gas mass, baryonic mass, gas temperature, Y and velocity dispersion as a function of virial mass. We verify that the mass and redshift slopes and the intrinsic scatter of the MORs are nearly independent of cosmology with variations significantly smaller than current observational uncertainties. We show that the gas mass and baryonic mass sensitively depends only on the baryon fraction, velocity dispersion, and gas temperature on h0, and Y on both baryon fraction and h0. We investigate the cosmological implications of our MOR parametrization on a mock catalogue created for an idealized eROSITA-like experiment. We show that our parametrization introduces a strong degeneracy between the cosmological parameters and the normalization of the MOR. Finally, the parameter constraints derived at different overdensity (Δ500c), for X-ray bolometric gas luminosity, and for different subgrid physics prescriptions are shown in the appendix.


CN-5
RU-D
(432)Encounters of merger and accretion shocks in galaxy clusters and their effects on intracluster medium
  • Congyao Zhang,
  • Eugene Churazov,
  • Klaus Dolag,
  • William R. Forman,
  • Irina Zhuravleva
Monthly Notices of the Royal Astronomical Society (05/2020) doi:10.1093/mnras/staa1013
abstract + abstract -

Several types/classes of shocks naturally arise during formation and evolution of galaxy clusters. One such class is represented by accretion shocks, associated with deceleration of infalling baryons. Such shocks, characterized by a very high Mach number, are present even in 1D models of cluster evolution. Another class is composed of 'runaway merger shocks', which appear when a merger shock, driven by a sufficiently massive infalling subcluster, propagates away from the main-cluster centre. We argue that, when the merger shock overtakes the accretion shock, a new long-living shock is formed that propagates to large distances from the main cluster (well beyond its virial radius), affecting the cold gas around the cluster. We refer to these structures as Merger-accelerated Accretion shocks (MA-shocks) in this paper. We show examples of such MA-shocks in one-dimensioanal (1D) and three-dimensional (3D) simulations and discuss their characteristic properties. In particular, (1) MA-shocks shape the boundary separating the hot intracluster medium (ICM) from the unshocked gas, giving this boundary a 'flower-like' morphology. In 3D, MA-shocks occupy space between the dense accreting filaments. (2) Evolution of MA-shocks highly depends on the Mach number of the runaway merger shock and the mass accretion rate parameter of the cluster. (3) MA-shocks may lead to the misalignment of the ICM boundary and the splashback radius.


MIAPbP
(431)Quark structure of the χ<SUB>c</SUB>(3 P ) and X(4274) resonances and their strong and radiative decays
  • J. Ferretti,
  • E. Santopinto,
  • M. Naeem Anwar,
  • Yu Lu
European Physical Journal C (05/2020) doi:10.1140/epjc/s10052-020-8032-5
abstract + abstract -

We calculate the masses of χc(3 P ) states with threshold corrections in a coupled-channel model. The model was recently applied to the description of the properties of χc(2 P ) and χb(3 P ) multiplets (Ferretti and Santopinto in Phys Lett B 789:550, 2019]. We also compute the open-charm strong decay widths of the χc(3 P ) states and their radiative transitions. According to our predictions, the χc(3 P ) states should be dominated by the charmonium core, but they may also show small meson-meson components. The X(4274) is interpreted as a c c ¯ χc 1(3 P ) state. More information on the other members of the χc(3 P ) multiplet, as well as a more rigorous analysis of the X(4274)'s decay modes, are needed to provide further indications on the quark structure of the previous resonance.


MIAPbP
(430)Electric dipole moments in a leptoquark scenario for the B-physics anomalies
  • Wolfgang Altmannshofer,
  • Stefania Gori,
  • Hiren H. Patel,
  • Stefano Profumo,
  • Douglas Tuckler
Journal of High Energy Physics (05/2020) doi:10.1007/JHEP05(2020)069
abstract + abstract -

Vector leptoquarks can address the lepton flavor universality anomalies in decays associated with the b → cℓν and b → sℓℓ transitions, as observed in recent years. While not required to explain the anomalies, these leptoquarks generically yield new sources of CP violation. In this paper, we explore constraints and discovery potential for electric dipole moments (EDMs) in leptonic and hadronic systems. We provide the most generic expressions for dipole moments induced by vector leptoquarks at one loop. We find that O(1) CP-violating phases in tau and muon couplings can lead to corresponding EDMs within reach of next-generation EDM experiments, and that existing bounds on the electron EDM already put stringent constraints on CP-violating electron couplings.


CN-5
RU-D
(429)On the origin of magnetic driven winds and the structure of the galactic dynamo in isolated galaxies
  • Ulrich P. Steinwandel,
  • Klaus Dolag,
  • Harald Lesch,
  • Benjamin P. Moster,
  • Andreas Burkert
  • +1
Monthly Notices of the Royal Astronomical Society (05/2020) doi:10.1093/mnras/staa817
abstract + abstract -

We investigate the build-up of the galactic dynamo and subsequently the origin of a magnetic driven outflow. We use a set-up of an isolated disc galaxy with a realistic circum-galactic medium (CGM). We find good agreement of the galactic dynamo with theoretical and observational predictions from the radial and toroidal components of the magnetic field as function of radius and disc scale height. We find several field reversals indicating dipole structure at early times and quadrupole structure at late times. Together with the magnetic pitch angle and the dynamo control parameters Rα, Rω, and D, we present strong evidence for an α2-Ω dynamo. The formation of a bar in the centre leads to further amplification of the magnetic field via adiabatic compression which subsequently drives an outflow. Due to the Parker instability the magnetic field lines rise to the edge of the disc, break out, and expand freely in the CGM driven by the magnetic pressure. Finally, we investigate the correlation between magnetic field and star formation rate. Globally, we find that the magnetic field is increasing as function of the star formation rate surface density with a slope between 0.3 and 0.45 in good agreement with predictions from theory and observations. Locally, we find that the magnetic field can decrease while star formation increases. We find that this effect is correlated with the diffusion of magnetic field from the spiral arms to the interarm regions which we explicitly include by solving the induction equation and accounting for non-linear terms.


MIAPbP
(428)The H I mass function of group galaxies in the ALFALFA survey
  • Michael G. Jones,
  • Kelley M. Hess,
  • Elizabeth A. K. Adams,
  • Lourdes Verdes-Montenegro
Monthly Notices of the Royal Astronomical Society (05/2020) doi:10.1093/mnras/staa810
abstract + abstract -

We estimate the H I mass function (HIMF) of galaxies in groups based on thousands of ALFALFA (Arecibo Legacy Fast ALFA survey) H I detections within the galaxy groups of four widely used SDSS (Sloan Digital Sky Survey) group catalogues. Although differences between the catalogues mean that there is no one definitive group galaxy HIMF, in general we find that the low-mass slope is flat, in agreement with studies based on small samples of individual groups, and that the 'knee' mass is slightly higher than that of the global HIMF of the full ALFALFA sample. We find that the observed fraction of ALFALFA galaxies in groups is approximately 22 per cent. These group galaxies were removed from the full ALFALFA source catalogue to calculate the field HIMF using the remaining galaxies. Comparison between the field and group HIMFs reveals that group galaxies make only a small contribution to the global HIMF as most ALFALFA galaxies are in the field, but beyond the HIMF 'knee' group galaxies dominate. Finally, we attempt to separate the group galaxy HIMF into bins of group halo mass, but find that too few low-mass galaxies are detected in the most massive groups to tightly constrain the slope, owing to the rarity of such groups in the nearby Universe where low-mass galaxies are detectable with existing H I surveys.


MIAPbP
(427)Direct Measurement of the H I-halo Mass Relation through Stacking
  • Hong Guo,
  • Michael G. Jones,
  • Martha P. Haynes,
  • Jian Fu
The Astrophysical Journal (05/2020) doi:10.3847/1538-4357/ab886f
abstract + abstract -

We present accurate measurements of the total H I mass in dark matter halos of different masses at z ∼ 0, by stacking the H I spectra of entire groups from the Arecibo Fast Legacy ALFA Survey. The halos are selected from the optical galaxy group catalog constructed from the Sloan Digital Sky Survey DR7 Main Galaxy sample, with reliable measurements of halo mass and halo membership. We find that the H I-halo mass relation is not a simple monotonic function, as assumed in several theoretical models. In addition to the dependence of halo mass, the total H I gas mass shows a strong dependence on the halo richness, with larger H I masses in groups with more members at fixed halo masses. Moreover, halos with at least three member galaxies in the group catalog have a sharp decrease of the H I mass, potentially caused by the virial halo shock-heating and the active galactic nucleus (AGN) feedback. The dominant contribution of the H I gas comes from the central galaxies for halos of ${M}_{{\rm{h}}}\lt {10}^{12.5}{h}^{-1}{M}_{\odot }$ , while the satellite galaxies dominate over more massive halos. Our measurements are consistent with a three-phase formation scenario of the H I-rich galaxies. The smooth cold gas accretion is driving the H I mass growth in halos of ${M}_{{\rm{h}}}\lt {10}^{11.8}{h}^{-1}{M}_{\odot }$ , with late-forming halos having more H I accreted. The virial halo shock-heating and AGN feedback will take effect to reduce the H I supply in halos of ${10}^{11.8}{h}^{-1}{M}_{\odot }\lt {M}_{{\rm{h}}}\lt {10}^{13}{h}^{-1}{M}_{\odot }$ . The H I mass in halos more massive than ${10}^{13}{h}^{-1}{M}_{\odot }$ generally grows by mergers, with the dependence on halo richness becoming much weaker.


MIAPbP
(426)The synthetic Emission Line COSMOS catalogue: Hα and [O II] galaxy luminosity functions and counts at 0.3 < z < 2.5
  • Shun Saito,
  • Sylvain de la Torre,
  • Olivier Ilbert,
  • Cédric Dubois,
  • Kiyoto Yabe
  • +1
MNRAS (05/2020) doi:10.1093/mnras/staa727
abstract + abstract -

Star-forming galaxies with strong nebular and collisional emission lines are privileged target galaxies in forthcoming cosmological large galaxy redshift surveys. We use the COSMOS2015 photometric catalogue to model galaxy spectral energy distributions and emission-line fluxes. We adopt an empirical but physically motivated model that uses information from the best-fitting spectral energy distribution of stellar continuum to each galaxy. The emission-line flux model is calibrated and validated against direct flux measurements in subsets of galaxies that have 3D-HST or zCOSMOS-Bright spectra. We take a particular care in modelling dust attenuation such that our model can explain both Hα and [O II] observed fluxes at different redshifts. We find that a simple solution to this is to introduce a redshift evolution in the dust attenuation fraction parameter, f = Estar(B - V)/Egas(B - V), as f(z) = 0.44 + 0.2z. From this catalogue, we derive the Hα and [O II] luminosity functions up to redshifts of about 2.5 after carefully accounting for emission line flux and redshift errors. This allows us to make predictions for Hα and [O II] galaxy number counts in next-generation cosmological redshift surveys. Our modelled emission lines and spectra in the COSMOS2015 catalogue shall be useful to study the target selection for planned next-generation galaxy redshift surveys and we make them publicly available as 'EL-COSMOS' on the ASPIC data base.


RU-D
(425)Properties of gamma-ray decay lines in 3D core-collapse supernova models, with application to SN 1987A and Cas A
  • A. Jerkstrand,
  • A. Wongwathanarat,
  • H. -T. Janka,
  • M. Gabler,
  • D. Alp
  • +6
  • R. Diehl,
  • K. Maeda,
  • J. Larsson,
  • C. Fransson,
  • A. Menon,
  • A. Heger
  • (less)
Monthly Notices of the Royal Astronomical Society (05/2020) doi:10.1093/mnras/staa736
abstract + abstract -

Comparison of theoretical line profiles to observations provides important tests for supernova explosion models. We study the shapes of radioactive decay lines predicted by current 3D core-collapse explosion simulations, and compare these to observations of SN 1987A and Cas A. Both the widths and shifts of decay lines vary by several thousand kilometres per second depending on viewing angle. The line profiles can be complex with multiple peaks. By combining observational constraints from 56Co decay lines, 44Ti decay lines, and Fe IR lines, we delineate a picture of the morphology of the explosive burning ashes in SN 1987A. For MZAMS = 15-20 M progenitors exploding with ∼1.5 × 1051 erg, ejecta structures suitable to reproduce the observations involve a bulk asymmetry of the 56Ni of at least ∼400 km s-1 and a bulk velocity of at least 1500 km s-1. By adding constraints to reproduce the UVOIR bolometric light curve of SN 1987A up to 600 d, an ejecta mass around 14 M is favoured. We also investigate whether observed decay lines can constrain the neutron star (NS) kick velocity. The model grid provides a constraint VNS > Vredshift, and applying this to SN 1987A gives a NS kick of at least 500 km s-1. For Cas A, our single model provides a satisfactory fit to the NuSTAR observations and reinforces the result that current neutrino-driven core-collapse SN models achieve enough bulk asymmetry in the explosive burning material. Finally, we investigate the internal gamma-ray field and energy deposition, and compare the 3D models to 1D approximations.


(424)Asymmetric spatial distribution of subsolar metallicity stars in the Milky Way nuclear star cluster
  • A. Feldmeier-Krause,
  • W. Kerzendorf,
  • T. Do,
  • F. Nogueras-Lara,
  • N. Neumayer
  • +8
  • C. J. Walcher,
  • A. Seth,
  • R. Schödel,
  • P. T. de Zeeuw,
  • M. Hilker,
  • Nora Lützgendorf,
  • H. Kuntschner,
  • M. Kissler-Patig
  • (less)
abstract + abstract -

We present stellar metallicity measurements of more than 600 late-type stars in the central 10 pc of the Galactic centre. Together with our previously published KMOS data, this data set allows us to investigate, for the first time, spatial variations of the nuclear star cluster's metallicity distribution. Using the integral-field spectrograph KMOS (VLT) we observed almost half of the area enclosed by the nuclear star cluster's effective radius. We extract spectra at medium spectral resolution, and apply full spectral fitting utilising the PHOENIX library of synthetic stellar spectra. The stellar metallicities range from [M/H]=-1.25 dex to [M/H]> +0.3 dex, with most of the stars having super-solar metallicity. We are able to measure an anisotropy of the stellar metallicity distribution. In the Galactic North, the portion of sub-solar metallicity stars with [M/H]<0.0 dex is more than twice as high as in the Galactic South. One possible explanation for different fractions of sub-solar metallicity stars in different parts of the cluster is a recent merger event. We propose to test this hypothesis with high-resolution spectroscopy, and by combining the metallicity information with kinematic data.


MIAPbP
(423)Conformal freeze-in of dark matter
  • Sungwoo Hong,
  • Gowri Kurup,
  • Maxim Perelstein
Physical Review D (05/2020) doi:10.1103/PhysRevD.101.095037
abstract + abstract -

We present the conformal freeze-in (COFI) scenario for dark matter production. At high energies, the dark sector is described by a gauge theory flowing toward a Banks-Zaks fixed point, coupled to the Standard Model via a nonrenormalizable portal interaction. In the early Universe, a nonthermal freeze-in process transfers energy from the standard model plasma to the dark sector. During the freeze-in, the dark sector is described by a strongly coupled conformal field theory. As the Universe cools, cosmological phase transitions in the Standard Model sector, either electroweak or QCD, induce conformal symmetry breaking and confinement in the dark sector. One of the resulting dark bound states is stable on the cosmological time scales and plays the role of dark matter. With the Higgs portal, the COFI scenario provides a viable dark matter candidate with mass in a phenomenologically interesting sub-MeV range. With the quark portal, a dark matter candidate with mass around 1 keV is consistent with observations. Conformal bootstrap may put a nontrivial constraint on model building in this case.


MIAPbP
(422)Two-Loop Four-Graviton Scattering Amplitudes
  • S. Abreu,
  • F. Febres Cordero,
  • H. Ita,
  • M. Jaquier,
  • B. Page
  • +2
Physical Review Letters (05/2020) doi:10.1103/PhysRevLett.124.211601
abstract + abstract -

We present the analytic form of the two-loop four-graviton scattering amplitudes in Einstein gravity. To remove ultraviolet divergences we include counterterms quadratic and cubic in the Riemann curvature tensor. The two-loop numerical unitarity approach is used to deal with the challenging momentum dependence of the interactions. We exploit the algebraic properties of the integrand of the amplitude in order to reduce it to a minimal basis of Feynman integrals. Analytic expressions are obtained from numerical evaluations of the amplitude. Finally, we show that four-graviton scattering observables depend on fewer couplings than naïvely expected.


MIAPbP
(421)Scalars Gliding through an Expanding Universe
  • Anson Hook,
  • Gustavo Marques-Tavares,
  • Yuhsin Tsai
Physical Review Letters (05/2020) doi:10.1103/PhysRevLett.124.211801
abstract + abstract -

In this Letter, we investigate the effects of single derivative mixing in massive bosonic fields. In the regime of large mixing, we show that this leads to striking changes of the field dynamics, delaying the onset of classical oscillations and decreasing, or even eliminating, the friction due to Hubble expansion. We highlight this phenomenon with a few examples. In the first example, we show how an axionlike particle can have its number abundance parametrically enhanced. In the second example, we demonstrate that the QCD axion can have its number abundance enhanced allowing for misalignment driven axion dark matter all the way down to fa of order astrophysical bounds. In the third example, we show that the delayed oscillation of the scalar field can also sustain a period of inflation. In the last example, we present a situation where an oscillating scalar field is completely frictionless and does not dilute away in time.


MIAPbP
(420)The Steinmann Cluster Bootstrap for N=4 Super Yang-Mills Amplitudes
  • Simon Caron-Huot,
  • Lance J. Dixon,
  • James M. Drummond,
  • Falko Dulat,
  • Jack Foster
  • +4
  • Ömer Gürdoğan,
  • Matt von Hippel,
  • Andrew J. McLeod,
  • Georgios Papathanasiou
  • (less)
abstract + abstract -

We review the bootstrap method for constructing six- and seven-particle amplitudes in planar $\mathcal{N}=4$ super Yang-Mills theory, by exploiting their analytic structure. We focus on two recently discovered properties which greatly simplify this construction at symbol and function level, respectively: the extended Steinmann relations, or equivalently cluster adjacency, and the coaction principle. We then demonstrate their power in determining the six-particle amplitude through six and seven loops in the NMHV and MHV sectors respectively, as well as the symbol of the NMHV seven-particle amplitude to four loops.


MIAPbP
(419)Cosmological parameters from the BOSS galaxy power spectrum
  • Mikhail M. Ivanov,
  • Marko Simonović,
  • Matias Zaldarriaga
Journal of Cosmology and Astroparticle Physics (05/2020) doi:10.1088/1475-7516/2020/05/042
abstract + abstract -

We present cosmological parameter measurements from the publicly available Baryon Oscillation Spectroscopic Survey (BOSS) data on anisotropic galaxy clustering in Fourier space. Compared to previous studies, our analysis has two main novel features. First, we use a complete perturbation theory model that properly takes into account the non-linear effects of dark matter clustering, short-scale physics, galaxy bias, redshift-space distortions, and large-scale bulk flows. Second, we employ a Markov-Chain Monte-Carlo technique and consistently reevaluate the full power spectrum likelihood as we scan over different cosmologies. Our baseline analysis assumes minimal ΛCDM, varies the neutrino masses within a reasonably tight range, fixes the primordial power spectrum tilt, and uses the big bang nucleosynthesis prior on the physical baryon density ωb. In this setup, we find the following late-Universe parameters: Hubble constant H0=(67.9± 1.1) km s-1Mpc-1, matter density fraction Ωm=0.295± 0.010, and the mass fluctuation amplitude σ8=0.721± 0.043. These parameters were measured directly from the BOSS data and independently of the Planck cosmic microwave background observations. Scanning over the power spectrum tilt or relaxing the other priors do not significantly alter our main conclusions. Finally, we discuss the information content of the BOSS power spectrum and show that it is dominated by the location of the baryon acoustic oscillations and the power spectrum shape. We argue that the contribution of the Alcock-Paczynski effect is marginal in ΛCDM, but becomes important for non-minimal cosmological models.


MIAPbP
(418)Flavourful SMEFT likelihood for Higgs and electroweak data
  • Adam Falkowski,
  • David Straub
Journal of High Energy Physics (04/2020) doi:10.1007/JHEP04(2020)066
abstract + abstract -

We perform an updated fit to LHC Higgs data and LEP electroweak precision tests in the framework of the Standard Model Effective Field Theory (SMEFT). We assume a generic structure of the SMEFT operators without imposing any flavour symmetries. The implementation is released as part of the public global SMEFT likelihood. This allows one to fit parameters of a broad class of new physics models to combined Higgs, electroweak, quark flavour, and lepton flavour observables.


MIAPbP
(417)On positive geometries of quartic interactions: Stokes polytopes, lower forms on associahedra and world-sheet forms
  • P. B. Aneesh,
  • Pinaki Banerjee,
  • Mrunmay Jagadale,
  • Renjan Rajan John,
  • Alok Laddha
  • +1
Journal of High Energy Physics (04/2020) doi:10.1007/JHEP04(2020)149
abstract + abstract -

In [1], two of the present authors along with P. Raman attempted to extend the Amplituhedron program for scalar field theories [2] to quartic scalar interactions. In this paper we develop various aspects of this proposal. Using recent seminal results in Representation theory [3, 4], we show that projectivity of scattering forms and existence of kinematic space associahedron completely capture planar amplitudes of quartic interaction. We generalise the results of [1] and show that for any n-particle amplitude, the positive geometry associated to the projective scattering form is a convex realisation of Stokes polytope which can be naturally embedded inside one of the ABHY associahedra defined in [2, 5]. For a special class of Stokes polytopes with hyper-cubic topology, we show that they have a canonical convex realisation in kinematic space as boundaries of kinematic space associahedra. We then use these kinematic space geometric constructions to write world-sheet forms for


MIAPbP
(416)Large effects from small QCD instantons: making soft bombs at hadron colliders
  • Valentin V. Khoze,
  • Frank Krauss,
  • Matthias Schott
Journal of High Energy Physics (04/2020) doi:10.1007/JHEP04(2020)201
abstract + abstract -

It is a common belief that the last missing piece of the Standard Model of particles physics was found with the discovery of the Higgs boson at the Large Hadron Collider. However, there remains a major prediction of quantum tunnelling processes mediated by instanton solutions in the Yang-Mills theory, that is still untested in the Standard Model. The direct experimental observation of instanton-induced processes, which are a consequence of the non-trivial vacuum structure of the Standard Model and of quantum tunnelling in QFT, would be a major breakthrough in modern particle physics. In this paper, we present for the first time a full calculation of QCD instanton-induced processes in proton-proton collisions accounting for quantum corrections due to both initial and final state gluon interactions, a first implementation in an MC event generator as well as a basic strategy how to observe these effects experimentally.


MIAPbP
(415)Extracting maximum information from polarised baryon decays via amplitude analysis: the $\Lambda^+_c \to pK^-\pi^+$ case
  • Daniele Marangotto
abstract + abstract -

We consider which is the maximum information measurable from the decay distributions of polarised baryon decays via amplitude analysis in the helicity formalism. We focus in particular on the analytical study of the $\Lambda^+_c \to pK^-\pi^+$ decay distributions, demonstrating that the full information on its decay amplitudes can be extracted from its distributions, allowing a simultaneous measurement of both helicity amplitudes and the polarisation vector. This opens the possibility to use the $\Lambda^+_c \to pK^-\pi^+$ decay for applications ranging from New Physics searches to low-energy QCD studies, in particular its use as absolute polarimeter for the $\Lambda^+_c$ baryon. This result is valid as well for baryon decays having the same spin structure and it is cross-checked numerically by means of a toy amplitude fit with Monte Carlo pseudo-data.


(414)Electron ionization via dark matter-electron scattering and the Migdal effect
  • Daniel Baxter,
  • Yonatan Kahn,
  • Gordan Krnjaic
Physical Review D (04/2020) doi:10.1103/PhysRevD.101.076014
abstract + abstract -

There are currently several existing and proposed experiments designed to probe sub-GeV dark matter (DM) using electron ionization in various materials. The projected signal rates for these experiments assume that this ionization yield arises only from DM scattering directly off electron targets, ignoring secondary ionization contributions from DM scattering off nuclear targets. We investigate the validity of this assumption and show that if sub-GeV DM couples with comparable strength to both protons and electrons, as would be the case for a dark photon mediator, the ionization signal from atomic scattering via the Migdal effect scales with the atomic number Z and 3-momentum transfer q as Z2q2. The result is that the Migdal effect is always subdominant to electron scattering when the mediator is light, but that Migdal-induced ionization can dominate over electron scattering for heavy mediators and DM masses in the hundreds of MeV range. We put these two ionization processes on identical theoretical footing, address some theoretical uncertainties in the choice of atomic wave functions used to compute rates, and discuss the implications for DM scenarios where the Migdal process dominates, including for XENON10, XENON100, and the recent XENON1T results on light DM scattering.


MIAPbP
(413)H I asymmetries in LVHIS, VIVA, and HALOGAS galaxies
  • T. N. Reynolds,
  • T. Westmeier,
  • L. Staveley-Smith,
  • G. Chauhan,
  • C. D. P. Lagos
Monthly Notices of the Royal Astronomical Society (04/2020) doi:10.1093/mnras/staa597
abstract + abstract -

We present an analysis of morphological, kinematic, and spectral asymmetries in observations of atomic neutral hydrogen (H I) gas from the Local Volume H I Survey (LVHIS), the VLA Imaging of Virgo in Atomic Gas (VIVA) survey, and the Hydrogen Accretion in Local Galaxies Survey. With the aim of investigating the impact of the local environment density and stellar mass on the measured H I asymmetries in future large H I surveys, we provide recommendations for the most meaningful measures of asymmetry for use in future analysis. After controlling for stellar mass, we find signs of statistically significant trends of increasing asymmetries with local density. The most significant trend we measure is for the normalized flipped spectrum residual (Aspec), with mean LVHIS and VIVA values of 0.204 ± 0.011 and 0.615 ± 0.068 at average weighted 10th nearest-neighbour galaxy number densities of log (ρ10/Mpc-3) = -1.64 and 0.88, respectively. Looking ahead to the Widefield ASKAP L-band Legacy All-sky Blind survey on the Australian Square Kilometre Array Pathfinder, we estimate that the number of detections will be sufficient to provide coverage over 5 orders of magnitude in both local density and stellar mass increasing the dynamic range and accuracy with which we can probe the effect of these properties on the asymmetry in the distribution of atomic gas in galaxies.


MIAPbP
(412)Singlet night in Feynman-ville: one-loop matching of a real scalar
  • Ulrich Haisch,
  • Maximilian Ruhdorfer,
  • Ennio Salvioni,
  • Elena Venturini,
  • Andreas Weiler
Journal of High Energy Physics (04/2020) doi:10.1007/JHEP04(2020)164
abstract + abstract -

A complete one-loop matching calculation for real singlet scalar extensions of the Standard Model to the Standard Model effective field theory (SMEFT) of dimension- six operators is presented. We compare our analytic results obtained by using Feynman diagrams to the expressions derived in the literature by a combination of the universal one-loop effective action (UOLEA) approach and Feynman calculus. After identifying contributions that have been overlooked in the existing calculations, we find that the pure diagrammatic approach and the mixed method lead to identical results. We highlight some of the subtleties involved in computing one-loop matching corrections in SMEFT.


MIAPbP
(411)Cataloging accreted stars within Gaia DR2 using deep learning
  • B. Ostdiek,
  • L. Necib,
  • T. Cohen,
  • M. Freytsis,
  • M. Lisanti
  • +4
  • S. Garrison-Kimmmel,
  • A. Wetzel,
  • R. E. Sanderson,
  • P. F. Hopkins
  • (less)
Astronomy and Astrophysics (04/2020) doi:10.1051/0004-6361/201936866
abstract + abstract -


Aims: The goal of this study is to present the development of a machine learning based approach that utilizes phase space alone to separate the Gaia DR2 stars into two categories: those accreted onto the Milky Way from those that are in situ. Traditional selection methods that have been used to identify accreted stars typically rely on full 3D velocity, metallicity information, or both, which significantly reduces the number of classifiable stars. The approach advocated here is applicable to a much larger portion of Gaia DR2.
Methods: A method known as "transfer learning" is shown to be effective through extensive testing on a set of mock Gaia catalogs that are based on the FIRE cosmological zoom-in hydrodynamic simulations of Milky Way-mass galaxies. The machine is first trained on simulated data using only 5D kinematics as inputs and is then further trained on a cross-matched Gaia/RAVE data set, which improves sensitivity to properties of the real Milky Way.
Results: The result is a catalog that identifies ∼767 000 accreted stars within Gaia DR2. This catalog can yield empirical insights into the merger history of the Milky Way and could be used to infer properties of the dark matter distribution.


RU-A
(410)The Optimal Strategy for ɛ <SUP>‧</SUP>/ɛ in the SM: 2019
  • Andrzej J. Buras
Journal of Physics Conference Series (04/2020) doi:10.1088/1742-6596/1526/1/012019
abstract + abstract -

Following the recent analysis done in collaboration with Jason Aebischer and Christoph Bobeth, I summarize the optimal, in our view, strategy for the present evaluation of the ratio ɛ /ɛ in the Standard Model. In particular, I emphasize the importance of the correct matching of the long-distance and short-distance contributions to ɛ /ɛ, which presently is only achieved by RBC-UKQCD lattice QCD collaboration and by the analytical Dual QCD approach. An important role play also the isospin-breaking and QED effects, which presently are best known from chiral perturbation theory, albeit still with a significant error. Finally, it is essential to include NNLO QCD corrections in order to reduce unphysical renormalization scheme and scale dependences present at the NLO level. Here µ c in m cc ) in the case of QCD penguin contributions and µ t in m tt ) in the case of electroweak penguin contributions play the most important roles. Presently the error on ɛ /ɛ is dominated by the uncertainties in the QCDP parameter B_6(1/2) and the isospin-breaking parameter \hat Ω {{eff}}. We present a table illustrating this.


RU-D
(409)Kinematics of simulated galaxies II: Probing the stellar kinematics of galaxies out to large radii
  • Felix Schulze,
  • Rhea-Silvia Remus,
  • Klaus Dolag,
  • Sabine Bellstedt,
  • Andreas Burkert
  • +1
Monthly Notices of the Royal Astronomical Society (04/2020) doi:10.1093/mnras/staa511
abstract + abstract -

We investigate the stellar kinematics of a sample of galaxies extracted from the hydrodynamic cosmological Magneticum Pathfinder simulations out to five half-mass radii. We construct differential radial stellar spin profiles quantified by the observationally widely used λ and the closely related (V/σ) parameters. We find three characteristic profile shapes: profiles exhibiting a (I) peak within 2.5 half-mass radii and a subsequent decrease; (II) continuous increase that plateaus at larger radii typically with a high amplitude; (III) completely flat behaviour typically with low amplitude, in agreement with observations. This shows that the kinematic state of the stellar component can vary significantly with radius, suggesting a distinct interplay between in-situ star formation and ex-situ accretion of stars. Following the evolution of our sample through time, we provide evidence that the accretion history of galaxies with decreasing profiles is dominated by the anisotropic accretion of low-mass satellites that get disrupted beyond ∼2.0 half-mass radii, building up a stellar halo with non-ordered motion while maintaining the central rotation already present at z = 2. In fact, at z = 2 decreasing profiles are the predominant profile class. Hence, we can predict a distinct formation pathway for galaxies with a decreasing profile and show that the centre resembles an old embedded disc. Furthermore, we show that the radius of the kinematic transition provides a good estimation for the transition radius from in-situ stars in the centre to accreted stars in the halo.


(408)Thermal Relic Targets with Exponentially Small Couplings
  • Raffaele Tito D'Agnolo,
  • Duccio Pappadopulo,
  • Joshua T. Ruderman,
  • Po-Jen Wang
Physical Review Letters (04/2020) doi:10.1103/PhysRevLett.124.151801
abstract + abstract -

If dark matter was produced in the early Universe by the decoupling of its annihilations into known particles, there is a sharp experimental target for the size of its coupling. We show that if dark matter was produced by inelastic scattering against a lighter particle from the thermal bath, then its coupling can be exponentially smaller than the coupling required for its production from annihilations. As an application, we demonstrate that dark matter produced by inelastic scattering against electrons provides new thermal relic targets for direct detection and fixed target experiments.


MIAPbP
(407)Linear point and sound horizon as purely geometric standard rulers
  • Márcio O'Dwyer,
  • Stefano Anselmi,
  • Glenn D. Starkman,
  • Pier-Stefano Corasaniti,
  • Ravi K. Sheth
  • +1
Physical Review D (04/2020) doi:10.1103/PhysRevD.101.083517
abstract + abstract -

The baryon acoustic oscillations feature (BAO) imprinted in the clustering correlation function is known to furnish us cosmic distance determinations that are independent of the cosmological-background model and the primordial perturbation parameters. These measurements can be accomplished rigorously by means of the purely geometric BAO methods. To date two different purely geometric BAO approaches have been proposed. The first exploits the linear-point standard ruler. The second, called correlation-function model-fitting, exploits the sound-horizon standard ruler. A key difference between them is that, when estimated from clustering data, the linear point makes use of a cosmological-model-independent procedure to extract the ratio of the ruler to the cosmic distance, while the correlation-function model-fitting relies on a phenomenological cosmological model for the correlation function. Nevertheless the two rulers need to be precisely defined independently of any specific observable (e.g., the BAO). We define the linear point and sound horizon and we fully characterize and compare the two rulers' cosmological-parameter dependence. We find that they are both geometrical (i.e., independent of the primordial cosmological parameters) within the required accuracy, and that they have the same parameter dependence for a wide range of parameter values. We estimate the rulers' best-fit values and errors, given the cosmological constraints obtained by the Planck Satellite team from their measurements of the cosmic microwave background temperature and polarization anisotropies. We do this for three different cosmological models encompassed by the purely geometric BAO methods. In each case we find that the relative errors of the two rulers coincide and they are insensitive to the assumed cosmological model. Interestingly both the linear point and the sound horizon shift by 0.5 σ when we do not fix the spatial geometry to be flat in Λ CDM . This points toward a sensitivity of the rulers to different cosmological models when they are estimated from the cosmic microwave background.


MIAPbP
(406)J /ψ p scattering length from GlueX threshold measurements
  • Igor I. Strakovsky,
  • Denis Epifanov,
  • Lubomir Pentchev
Physical Review C (04/2020) doi:10.1103/PhysRevC.101.042201
abstract + abstract -

The quality of the recent GlueX J /ψ photoproduction data from Hall D at Jefferson Laboratory and the proximity of the data to the energy threshold, gives access to a variety of interesting physics aspects. As an example, an estimation of the J /ψ -nucleon scattering length αJ /ψ p is provided within the vector meson dominance model. It results in | αJ /ψ p|=(3.08 ±0.55 (stat . ) ±0.42 (syst . ) ) mfm which is much smaller than a typical size of a hadron.


RU-C
(405)Gravitational Wave from Axion-SU(2) Gauge Fields: Effective Field Theory for Kinetically Driven Inflation
  • Yuki Watanabe,
  • Eiichiro Komatsu
arXiv e-prints (04/2020) e-Print:2004.04350
abstract + abstract -

Building on Weinberg's approach to effective field theory for inflation, we construct an effective Lagrangian for a pseudo scalar (axion) inflaton field with shift symmetry. In this Lagrangian we allow the axion field to couple to non-Abelian gauge fields via a Chern-Simons term. We then analyze a class of inflation models driven by kinetic terms. We find that the observational constraints on the amplitudes of curvature perturbations and non-Gaussianity yield a lower bound for the tensor-to-scalar ratio of $r\gtrsim 5\times 10^{-3}$ from the vacuum fluctuation. The sourced gravitational wave from SU(2) gauge fields further increases the tensor-to-scalar ratio and makes the total gravitational wave partially chiral and non-Gaussian, which can be probed by polarization of the cosmic microwave background and direct detection experiments. We discuss constraints on parameter space due to backreaction of spin-2 particles produced by the gauge field.


MIAPbP
(404)Small-scale Structure Traced by Neutral Hydrogen Absorption in the Direction of Multiple-component Radio Continuum Sources
  • Daniel R. Rybarczyk,
  • Snezana Stanimirović,
  • Ellen G. Zweibel,
  • Claire E. Murray,
  • John M. Dickey
  • +2
The Astrophysical Journal (04/2020) doi:10.3847/1538-4357/ab83f7
abstract + abstract -

We have studied the small-scale distribution of atomic hydrogen (H I) using 21 cm absorption spectra against multiple-component background radio continuum sources from the 21-SPONGE survey and the Millennium Arecibo Absorption-Line Survey. We have found >5σ optical depth variations at a level of ∼0.03-0.5 between 13 out of 14 adjacent sightlines separated by a few arcseconds to a few arcminutes, suggesting the presence of neutral structures on spatial scales from a few to thousands of au (which we refer to as tiny-scale atomic structure, TSAS). The optical depth variations are strongest in directions where the H I column density and the fraction of H I in the cold neutral medium (CNM) are highest, which tend to be at low Galactic latitudes. By measuring changes in the properties of Gaussian components fitted to the absorption spectra, we find that changes in both the peak optical depth and the linewidth of TSAS absorption features contribute to the observed optical depth variations, while changes in the central velocity do not appear to strongly impact the observed variations. Both thermal and turbulent motions contribute appreciably to the linewidths, but the turbulence does not appear strong enough to confine overpressured TSAS. In a majority of cases, the TSAS column densities are sufficiently high that these structures can radiatively cool fast enough to maintain thermal equilibrium with their surroundings, even if they are overpressured. We also find that a majority of TSAS is associated with the CNM. For TSAS in the direction of the Taurus molecular cloud and the local Leo cold cloud, we estimate densities over an order of magnitude higher than typical CNM densities.


MIAPbP
(403)UV sensitivity of the axion mass from instantons in partially broken gauge groups
  • Csaba Csáki,
  • Maximilian Ruhdorfer,
  • Yuri Shirman
Journal of High Energy Physics (04/2020) doi:10.1007/JHEP04(2020)031
abstract + abstract -

We examine the contribution of small instantons to the axion mass in various UV completions of QCD. We show that the reason behind the potential dominance of such contributions is the non-trivial embedding of QCD into the UV theory. The effects from instantons in the partially broken gauge group appear as "fractional instanton" corrections in the effective theory. These will exhibit unusual dependences on the various scales in the problem whenever the index of embedding is non-trivial. We present a full one-instanton calculation of the axion mass in the simplest product group models, carefully keeping track of numerical prefactors. Rather than using a 't Hooft operator approximation we directly evaluate the contributions to the vacuum bubble, automatically capturing the effects of closing up external fermion lines with Higgs loops. This approach is manifestly finite and removes the uncertainty associated with introducing a cutoff scale for the Higgs loops. We verify that the small instantons may dominate over the QCD contribution for very high breaking scales and at least three group factors.


MIAPbP
(402)Polarized Initial States of Primordial Gravitational Waves
  • Sugumi Kanno,
  • Jiro Soda
Symmetry (04/2020) doi:10.3390/sym12040672
abstract + abstract -

Polarizations of primordial gravitational waves can be relevant when considering inflationary universe in modified gravity or when matter fields survive during inflation. Such polarizations have been discussed in the Bunch-Davies vacuum. Instead of taking into account dynamical generation of polarizations of gravitational waves, in this paper, we consider polarized initial states constructed from $SU(2)$ coherent states. We then evaluate the power spectrums of the primordial gravitational waves in the states.


RU-A
(401)Clustering of B ¯→D<SUP>(∗)</SUP>τ<SUP>-</SUP>ν<SUB>¯τ</SUB> kinematic distributions with ClusterKinG
  • Jason Aebischer,
  • Thomas Kuhr,
  • Kilian Lieret
Journal of High Energy Physics (04/2020) doi:10.1007/JHEP04(2020)007
abstract + abstract -

New Physics can manifest itself in kinematic distributions of particle decays. The parameter space defining the shape of such distributions can be large which is chalenging for both theoretical and experimental studies. Using clustering algorithms, the parameter space can however be dissected into subsets (clusters) which correspond to similar kinematic distributions. Clusters can then be represented by benchmark points, which allow for less involved studies and a concise presentation of the results. We demonstrate this concept using the Python package ClusterKinG, an easy to use framework for the clustering of distributions that particularly aims to make these techniques more accessible in a High Energy Physics context. As an example we consider B ¯→D(∗)τ-ν¯τ distributions and discuss various clustering methods and possible implications for future experimental analyses.


RU-D
(400)Planet-induced Vortices with Dust Coagulation in Protoplanetary Disks
  • Ya-Ping Li,
  • Hui Li,
  • Shengtai Li,
  • Tilman Birnstiel,
  • Joanna Drążkowska
  • +1
The Astrophysical Journal (04/2020) doi:10.3847/2041-8213/ab7fb2
abstract + abstract -

In this work, we study how the dust coagulation/fragmentation will influence the evolution and observational appearances of vortices induced by a massive planet embedded in a low-viscosity disk by performing global 2D high-resolution hydrodynamical simulations. Within the vortex, due to its higher gas surface density and steeper pressure gradients, dust coagulation, fragmentation, and drift (to the vortex center) are all quite efficient, producing dust particles ranging from 1 μm to ∼1.0 cm, as well as an overall high dust-to-gas ratio (above unity). In addition, the dust size distribution is quite nonuniform inside the vortex, with the mass-weighted average dust size at the vortex center (∼4.0 mm) being a factor of ∼10 larger than other vortex regions. Both large (∼millimeter) and small (tens of microns) particles contribute strongly to affect the gas motion within the vortex. As such, we find that the inclusion of dust coagulation has a significant impact on the vortex lifetime and the typical vortex lifetime is about 1000 orbits. After the initial gaseous vortex is destroyed, the dust spreads into a ring with a few remaining smaller gaseous vortices with a high dust concentration and a large maximum size (∼millimeter). At late time, the synthetic dust continuum images for the coagulation case show as a ring inlaid with several hot spots at the 1.33 mm band, while only distinct hot spots remain at 7.0 mm.


RU-D
(399)ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT). I. CO, CS, CN, and H<SUB>2</SUB>CO around DG Tau B
  • A. Garufi,
  • L. Podio,
  • C. Codella,
  • K. Rygl,
  • F. Bacciotti
  • +5
  • S. Facchini,
  • D. Fedele,
  • A. Miotello,
  • R. Teague,
  • L. Testi
  • (less)
Astronomy and Astrophysics (04/2020) doi:10.1051/0004-6361/201937247
abstract + abstract -

The chemical composition of planets is determined by the distribution of the various molecular species in the protoplanetary disk at the time of their formation. To date, only a handful of disks have been imaged in multiple spectral lines with high spatial resolution. As part of a small campaign devoted to the chemical characterization of disk-outflow sources in Taurus, we report on new ALMA Band 6 (~1.3 mm) observations with ~0.15'' (20 au) resolution toward the embedded young star DG Tau B. Images of the continuum emission reveals a dust disk with rings and, putatively, a leading spiral arm. The disk, as well as the prominent outflow cavities, are detected in CO, H2CO, CS, and CN; instead, they remain undetected in SO2, HDO, and CH3OH. From the absorption of the back-side outflow, we inferred that the disk emission is optically thick in the inner 50 au. This morphology explains why no line emission is detected from this inner region and poses some limitations toward the calculation of the dust mass and the characterization of the inner gaseous disk. The H2CO and CS emission from the inner 200 au is mostly from the disk, and their morphology is very similar. The CN emission significantly differs from the other two molecules as it is observed only beyond 150 au. This ring-like morphology is consistent with previous observations and the predictions of thermochemical disk models. Finally, we constrained the disk-integrated column density of all molecules. In particular, we found that the CH3OH/H2CO ratio must be smaller than ~2, making the methanol non-detection still consistent with the only such ratio available from the literature (1.27 in TW Hya).

The reduced datacubes are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/636/A65


CN-3
RU-C
(398)The Schrödinger-Poisson method for Large-Scale Structure
  • Mathias Garny,
  • Thomas Konstandin,
  • Henrique Rubira
abstract + abstract -

We study the Schrödinger-Poisson (SP) method in the context of cosmological large-scale structure formation in an expanding background. In the limit ℏ→0, the SP technique can be viewed as an effective method to sample the phase space distribution of cold dark matter that remains valid on non-linear scales. We present results for the 2D and 3D matter correlation function and power spectrum at length scales corresponding to the baryon acoustic oscillation (BAO) peak. We discuss systematic effects of the SP method applied to cold dark matter and explore how they depend on the simulation parameters. In particular, we identify a combination of simulation parameters that controls the scale-independent loss of power observed at low redshifts, and discuss the scale relevant to this effect.


RU-A
(397)Heavy-Quark Expansion for B¯s→D(∗)s Form Factors and Unitarity Bounds beyond the SU(3)F Limit
  • Marzia Bordone,
  • Nico Gubernari,
  • Martin Jung,
  • Danny van Dyk
The European Physical Journal C (04/2020) e-Print:1912.09335 doi:10.1140/epjc/s10052-020-7850-9
abstract + abstract -

We carry out a comprehensive analysis of the full set of B¯q→D(∗)q form factors for spectator quarks q=u,d,s within the framework of the Heavy-Quark Expansion (HQE) to order O(αs,1/mb,1/m2c). In addition to the available lattice QCD calculations we make use of two new sets of theoretical constraints: we produce for the first time numerical predictions for the full set of B¯s→D(∗)s form factors using Light-Cone Sum Rules with Bs-meson distribution amplitudes. Furthermore, we reassess the QCD three-point sum rule results for the Isgur-Wise functions entering all our form factors for both q=u,d and q=s spectator quarks. These additional constraints allow us to go beyond the commonly used assumption of SU(3)F symmetry for the B¯s→D(∗)s form factors, especially in the unitarity constraints which we impose throughout our analysis. We find the coefficients of the IW functions emerging at O(1/m2c) to be consistent with the naive O(1) expectation, indicating a good convergence of the HQE. While we do not find significant SU(3) breaking, the explicit treatment of q=s as compared to a simple symmetry assumption renders the unitarity constraints more effective. We find that the (pseudo)scalar bounds are saturated to a large degree, which affects our theory predictions. We analyze the phenomenological consequences of our improved form factors by extracting |Vcb| from B¯→D(∗)ℓν decays and producing theoretical predictions for the lepton-flavour universality ratios R(D), R(D∗), R(Ds) and R(D∗s), as well as the τ- and D∗q polarization fractions for the B¯q→D(∗)qτν modes.


IDSL
RU-E
(396)CO2 reduction driven by a pH gradient
  • Reuben Hudson,
  • Ruvan de Graaf,
  • Mari Strandoo Rodin,
  • Aya Ohno,
  • Nick Lane
  • +6
  • Shawn E. McGlynn,
  • Yoichi M. A. Yamada,
  • Ryuhei Nakamura,
  • Laura M. Barge,
  • Dieter Braun,
  • and Victor Sojo
  • (less)
abstract + abstract -

All life on Earth is built of organic molecules, so the primordial sources of reduced carbon remain a major open question in studies of the origin of life. A variant of the alkaline-hydrothermal-vent theory for life’s emergence suggests that organics could have been produced by the reduction of CO2 via H2 oxidation, facilitated by geologically sustained pH gradients. The process would be an abiotic analog—and proposed evolutionary predecessor—of the Wood–Ljungdahl acetyl-CoA pathway of modern archaea and bacteria. The first energetic bottleneck of the pathway involves the endergonic reduction of CO2 with H2 to formate (HCOO–), which has proven elusive in mild abiotic settings. Here we show the reduction of CO2 with H2 at room temperature under moderate pressures (1.5 bar), driven by microfluidic pH gradients across inorganic Fe(Ni)S precipitates. Isotopic labeling with 13C confirmed formate production. Separately, deuterium (2H) labeling indicated that electron transfer to CO2 does not occur via direct hydrogenation with H2 but instead, freshly deposited Fe(Ni)S precipitates appear to facilitate electron transfer in an electrochemical-cell mechanism with two distinct half-reactions. Decreasing the pH gradient significantly, removing H2, or eliminating the precipitate yielded no detectable product. Our work demonstrates the feasibility of spatially separated yet electrically coupled geochemical reactions as drivers of otherwise endergonic processes. Beyond corroborating the ability of early-Earth alkaline hydrothermal systems to couple carbon reduction to hydrogen oxidation through biologically relevant mechanisms, these results may also be of significance for industrial and environmental applications, where other redox reactions could be facilitated using similarly mild approaches.


MIAPbP
(395)Toward a robust inference method for the galaxy bispectrum: likelihood function and model selection
  • Andrea Oddo,
  • Emiliano Sefusatti,
  • Cristiano Porciani,
  • Pierluigi Monaco,
  • Ariel G. Sánchez
Journal of Cosmology and Astroparticle Physics (03/2020) doi:10.1088/1475-7516/2020/03/056
abstract + abstract -

The forthcoming generation of galaxy redshift surveys will sample the large-scale structure of the Universe over unprecedented volumes with high-density tracers. This advancement will make robust measurements of three-point clustering statistics possible. In preparation for this improvement, we investigate how several methodological choices can influence inferences based on the bispectrum about galaxy bias and shot noise. We first measure the real-space bispectrum of dark-matter haloes extracted from 298 N-body simulations covering a volume of approximately 1000 Gpc3. We then fit a series of theoretical models based on tree-level perturbation theory to the numerical data. To achieve this, we estimate the covariance matrix of the measurement errors by using 10,000 mock catalogues generated with the PINOCCHIO code. We study how the model constraints are influenced by the binning strategy for the bispectrum configurations and by the form of the likelihood function. We also use Bayesian model-selection techniques to single out the optimal theoretical description of our data. We find that a three-parameter bias model combined with Poissonian shot noise is necessary to model the halo bispectrum up to scales of kmaxlesssim 0.08 Mpc-1, although fitting formulae that relate the bias parameters can be helpful to reduce the freedom of the model without compromising accuracy. Our data clearly disfavour local Eulerian and local Lagrangian bias models and do not require corrections to Poissonian shot noise. We anticipate that model-selection diagnostics will be particularly useful to extend the analysis to smaller scales as, in this case, the number of model parameters will grow significantly large.


MIAPbP
(394)Dust entrainment in photoevaporative winds: The impact of X-rays
  • R. Franz,
  • G. Picogna,
  • B. Ercolano,
  • T. Birnstiel
Astronomy and Astrophysics (03/2020) doi:10.1051/0004-6361/201936615
abstract + abstract -

Context. X-ray- and extreme ultraviolet (XEUV) driven photoevaporative winds acting on protoplanetary disks around young T Tauri stars may crucially impact disk evolution, affecting both gas and dust distributions.
Aims: We investigate the dust entrainment in XEUV-driven photoevaporative winds and compare our results to existing magnetohydrodynamic and EUV-only models.
Methods: We used a 2D hydrodynamical gas model of a protoplanetary disk irradiated by both X-ray and EUV spectra from a central T Tauri star to trace the motion of passive Lagrangian dust grains of various sizes. The trajectories were modelled starting at the disk surface in order to investigate dust entrainment in the wind.
Results: For an X-ray luminosity of LX = 2 × 1030 erg s-1 emitted by a M* = 0.7 M star, corresponding to a wind mass-loss rate of Ṁw ≃ 2.6 × 10-8 M yr-1, we find dust entrainment for sizes a0 ≲ 11 μm (9 μm) from the inner 25 AU (120 AU). This is an enhancement over dust entrainment in less vigorous EUV-driven winds with Ṁw ≃ 10-10 M yr-1. Our numerical model also shows deviations of dust grain trajectories from the gas streamlines even for μm-sized particles. In addition, we find a correlation between the size of the entrained grains and the maximum height they reach in the outflow.
Conclusions: X-ray-driven photoevaporative winds are expected to be dust-rich if small grains are present in the disk atmosphere.


MIAPbP
(393)The axion mass from 5D small instantons
  • Tony Gherghetta,
  • Valentin V. Khoze,
  • Alex Pomarol,
  • Yuri Shirman
Journal of High Energy Physics (03/2020) doi:10.1007/JHEP03(2020)063
abstract + abstract -

We calculate a new contribution to the axion mass that arises from gluons propagating in a 5th dimension at high energies. By uplifting the 4D instanton solution to five dimensions, the positive frequency modes of the Kaluza-Klein states generate a power-law term in the effective action that inversely grows with the instanton size. This causes 5D small instantons to enhance the axion mass in a way that does not spoil the axion solution to the strong CP problem. Moreover this enhancement can be much larger than the usual QCD contribution from large instantons, although it requires the 5D gauge theory to be near the non-perturbative limit. Thus our result suggests that the mass range of axions (or axion-like particles), which is important for ongoing experimental searches, can depend sensitively on the UV modification of QCD.


MIAPbP
(392)Exploring S-wave threshold effects in QCD: A heavy-light approach
  • Estia Eichten,
  • Ciaran Hughes
Physics Letters B (03/2020) doi:10.1016/j.physletb.2020.135250
abstract + abstract -

QCD exhibits complex dynamics near S-wave two-body thresholds. For light mesons, we see this in the failure of quark models to explain the f0 (500) and K0* (700) masses. For charmonium, an unexpected X (3872) state appears at the open charm threshold. In heavy-light systems, analogous threshold effects appear for the lowest JP =0+ and 1+ states in the Ds and Bs systems. Here we describe how lattice QCD can be used to understand these threshold dynamics by smoothly varying the strange-quark mass when studying the heavy-light systems. Small perturbations around the physical strange quark mass are used so to always remain near the physical QCD dynamics. This calculation is a straightforward extension of those already in the literature and can be undertaken by multiple lattice QCD collaborations with minimal computational cost.


MIAPbP
(391)Metastable nuclear isomers as dark matter accelerators
  • Maxim Pospelov,
  • Surjeet Rajendran,
  • Harikrishnan Ramani
Physical Review D (03/2020) doi:10.1103/PhysRevD.101.055001
abstract + abstract -

Inelastic dark matter and strongly interacting dark matter are poorly constrained by direct detection experiments since they both require the scattering event to deliver energy from the nucleus into the dark matter in order to have observable effects. We propose to test these scenarios by searching for the collisional deexcitation of metastable nuclear isomers by the dark matter particles. The longevity of these isomers is related to a strong suppression of γ - and β -transitions, typically inhibited by a large difference in the angular momentum for the nuclear transition. The collisional deexcitation by dark matter is possible since heavy dark matter particles can have a momentum exchange with the nucleus comparable to the inverse nuclear size, hence lifting tremendous angular momentum suppression of the nuclear transition. This deexcitation can be observed either by searching for the direct effects of the decaying isomer, or through the rescattering or decay of excited dark matter states in a nearby conventional dark matter detector setup. Existing nuclear isomer sources such as naturally occurring Tam180 , Bam137 produced in decaying Cesium in nuclear waste, Lum177 from medical waste, and Hfm178 from the Department of Energy storage can be combined with current dark matter detector technology to search for this class of dark matter.


RU-D
(390)Questioning the spatial origin of complex organic molecules in young protostars with the CALYPSO survey
  • A. Belloche,
  • A. J. Maury,
  • S. Maret,
  • S. Anderl,
  • A. Bacmann
  • +10
  • Ph. André,
  • S. Bontemps,
  • S. Cabrit,
  • C. Codella,
  • M. Gaudel,
  • F. Gueth,
  • C. Lefèvre,
  • B. Lefloch,
  • L. Podio,
  • L. Testi
  • (less)
Astronomy and Astrophysics (03/2020) doi:10.1051/0004-6361/201937352
abstract + abstract -

Context. Complex organic molecules (COMs) have been detected in a few Class 0 protostars but their origin is not well understood. While the usual picture of a hot corino explains their presence as resulting from the heating of the inner envelope by the nascent protostar, shocks in the outflow, disk wind, the presence of a flared disk, or the interaction region between envelope and disk at the centrifugal barrier have also been claimed to enhance the abundance of COMs.
Aims: Going beyond studies of individual objects, we want to investigate the origin of COMs in young protostars on a statistical basis.
Methods: We use the CALYPSO survey performed with the Plateau de Bure Interferometer of the Institut de Radioastronomie Millimétrique to search for COMs at high angular resolution in a sample of 26 solar-type protostars, including 22 Class 0 and four Class I objects. We derive the column densities of the detected molecules under the local thermodynamic equilibrium approximation and search for correlations between their abundances and with various source properties.
Results: Methanol is detected in 12 sources and tentatively in one source, which represents half of the sample. Eight sources (30%) have detections of at least three COMs. We find a strong chemical differentiation in multiple systems with five systems having one component with at least three COMs detected but the other component devoid of COM emission. All sources with a luminosity higher than 4 L have at least one detected COM whereas no COM emission is detected in sources with internal luminosity lower than 2 L, likely because of a lack of sensitivity. Internal luminosity is found to be the source parameter impacting the COM chemical composition of the sources the most, while there is no obvious correlation between the detection of COM emission and that of a disk-like structure. A canonical hot-corino origin may explain the COM emission in four sources, an accretion-shock origin in two or possibly three sources, and an outflow origin in three sources. The CALYPSO sources with COM detections can be classified into three groups on the basis of the abundances of oxygen-bearing molecules, cyanides, and CHO-bearing molecules. These chemical groups correlate neither with the COM origin scenarios, nor with the evolutionary status of the sources if we take the ratio of envelope mass to internal luminosity as an evolutionary tracer. We find strong correlations between molecules that are a priori not related chemically (for instance methanol and methyl cyanide), implying that the existence of a correlation does not imply a chemical link.
Conclusions: The CALYPSO survey has revealed a chemical differentiation in multiple systems that is markedly different from the case of the prototypical binary IRAS 16293-2422. This raises the question of whether all low-mass protostars go through a phase showing COM emission. A larger sample of young protostars and a more accurate determination of their internal luminosity will be necessary to make further progress. Searching for correlations between the COM emission and the jet/outflow properties of the sources may also be promising.

Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

The CALYPSO calibrated visibility tables and maps are publicly available at http://www.iram-institute.org/EN/content-page-317-7-158-240-317-0.html


CN-3
RU-B
(389)Probing multicomponent FIMP scenarios with gamma-ray telescopes
  • Johannes Herms,
  • Alejandro Ibarra
Journal of Cosmology and Astroparticle Physics (03/2020) doi:10.1088/1475-7516/2020/03/026
abstract + abstract -

We consider a scenario where the dark sector includes two Feebly Interacting Massive Particles (FIMPs), with couplings to the Standard Model particles that allow their production in the Early Universe via thermal freeze-in. These couplings generically lead to the decay of the heavier dark matter component into the lighter, possibly leading to observable signals of the otherwise elusive FIMPs. Concretely, we argue that the loop induced decay ψ2→ψ1γ for fermionic FIMPs, or phi2→phi1γγ for scalar FIMPs, could have detectable rates for model parameters compatible with the observed dark matter abundance.


RU-D
(388)Gas accretion damped by dust back-reaction at the snow line
  • Matías Gárate,
  • Til Birnstiel,
  • Joanna Drążkowska,
  • Sebastian Markus Stammler
Astronomy and Astrophysics (03/2020) doi:10.1051/0004-6361/201936067
abstract + abstract -

Context. The water snow line divides dry and icy solid material in protoplanetary disks. It has been thought to significantly affect planet formation at all stages. If dry particles break up more easily than icy ones, then the snow line causes a traffic jam because small grains drift inward at lower speeds than larger pebbles.
Aims: We aim to evaluate the effect of high dust concentrations around the snow line onto the gas dynamics.
Methods: Using numerical simulations, we modeled the global radial evolution of an axisymmetric protoplanetary disk. Our model includes particle growth, the evaporation and recondensation of water, and the back-reaction of dust onto the gas. The model takes into account the vertical distribution of dust particles.
Results: We find that the dust back-reaction can stop and even reverse the net flux of gas outside the snow line, decreasing the gas accretion rate onto the star to under 50% of its initial value. At the same time, the dust accumulates at the snow line, reaching dust-to-gas ratios of ɛ ≳ 0.8, and it delivers large amounts of water vapor towards the inner disk as the icy particles cross the snowline. However, the accumulation of dust at the snow line and the decrease in the gas accretion rate only take place if the global dust-to-gas ratio is high (ɛ0 ≳ 0.03), the viscous turbulence is low (αν ≲ 10-3), the disk is large enough (rc ≳ 100 au), and only during the early phases of the disk evolution (t ≲ 1 Myr). Otherwise the dust back-reaction fails to perturb the gas motion.


MIAPbP
(387)Asteroseismology: Radial oscillations of neutron stars with realistic equation of state
  • V. Sagun,
  • G. Panotopoulos,
  • I. Lopes
Physical Review D (03/2020) doi:10.1103/PhysRevD.101.063025
abstract + abstract -

We study radial oscillations of non-rotating neutron stars (NSs) in four-dimensional general relativity. The interior of the NS was modeled within a recently proposed multicomponent realistic equation of state (EoS) with the induced surface tension (IST). In particular, we considered the IST EoS with two sets of model parameters, that both reproduce all the known properties of normal nuclear matter, give a high quality description of the proton flow constraint, hadron multiplicities created in nuclear-nuclear collisions, consistent with astrophysical observations and the observational data from the NS-NS merger. We computed the 12 lowest radial oscillation modes, their frequencies and corresponding eigenfunctions, as well as the large frequency separation for six selected fiducial NSs (with different radii and masses of 1.2, 1.5 and 1.9 solar masses) of the two distinct model sets. The calculated frequencies show their continuous growth with an increase of the NS central baryon density. Moreover, we found correlations between the behavior of the first eigenfunction calculated for the fundamental mode, the adiabatic index and the speed of sound profile, which could be used to probe the internal structure of NSs with the asteroseismology data.


CN-2
RU-D
(386)Detectability of embedded protoplanets from hydrodynamical simulations
  • E. Sanchis,
  • G. Picogna,
  • B. Ercolano,
  • L. Testi,
  • G. Rosotti
Monthly Notices of the Royal Astronomical Society (03/2020) doi:10.1093/mnras/staa074
abstract + abstract -

We predict magnitudes for young planets embedded in transition discs, still affected by extinction due to material in the disc. We focus on Jupiter-sized planets at a late stage of their formation, when the planet has carved a deep gap in the gas and dust distributions and the disc starts to being transparent to the planet flux in the infrared (IR). Column densities are estimated by means of three-dimensional hydrodynamical models, performed for several planet masses. Expected magnitudes are obtained by using typical extinction properties of the disc material and evolutionary models of giant planets. For the simulated cases located at 5.2 au in a disc with a local unperturbed surface density of 127 g cm^{-2}, a 1MJ planet is highly extinct in the J, H, and Kbands, with predicted absolute magnitudes ≥ 50 mag. In the L and Mbands, extinction decreases, with planet magnitudes between 25 and 35 mag. In the Nband, due to the silicate feature on the dust opacities, the expected magnitude increases to ∼40 mag. For a 2MJ planet, the magnitudes in the J, H, and Kbands are above 22 mag, while for the L, M, and Nbands, the planet magnitudes are between 15 and 20 mag. For the 5MJ planet, extinction does not play a role in any IR band, due to its ability to open deep gaps. Contrast curves are derived for the transition discs in CQ Tau, PDS 70, HL Tau, TW Hya, and HD 163296. Planet mass upper limits are estimated for the known gaps in the last two systems.


(385)MSTAR - a fast parallelized algorithmically regularized integrator with minimum spanning tree coordinates
  • Antti Rantala,
  • Pauli Pihajoki,
  • Matias Mannerkoski,
  • Peter H. Johansson,
  • Thorsten Naab
Monthly Notices of the Royal Astronomical Society (03/2020) doi:10.1093/mnras/staa084
abstract + abstract -

We present the novel algorithmically regularized integration method MSTAR for high-accuracy (|ΔE/E| ≳ 10-14) integrations of N-body systems using minimum spanning tree coordinates. The twofold parallelization of the O(N_part^2) force loops and the substep divisions of the extrapolation method allow for a parallel scaling up to NCPU = 0.2 × Npart. The efficient parallel scaling of MSTAR makes the accurate integration of much larger particle numbers possible compared to the traditional algorithmic regularization chain (AR-CHAIN) methods, e.g. Npart = 5000 particles on 400 CPUs for 1 Gyr in a few weeks of wall-clock time. We present applications of MSTAR on few particle systems, studying the Kozai mechanism and N-body systems like star clusters with up to Npart = 104 particles. Combined with a tree or fast multipole-based integrator, the high performance of MSTAR removes a major computational bottleneck in simulations with regularized subsystems. It will enable the next-generation galactic-scale simulations with up to 109 stellar particles (e.g. m_\star = 100 M_⊙ for an M_\star = 10^{11} M_⊙ galaxy), including accurate collisional dynamics in the vicinity of nuclear supermassive black holes.


(384)Exploring the diversity of Type 1 active galactic nuclei identified in SDSS-IV/SPIDERS
  • Julien Wolf,
  • Mara Salvato,
  • Damien Coffey,
  • Andrea Merloni,
  • Johannes Buchner
  • +6
  • Riccardo Arcodia,
  • Dalya Baron,
  • Francisco J. Carrera,
  • Johan Comparat,
  • Donald P. Schneider,
  • Kirpal Nandra
  • (less)
Monthly Notices of the Royal Astronomical Society (03/2020) doi:10.1093/mnras/staa018
abstract + abstract -

We present a statistical analysis of the optical properties of an X-ray-selected Type 1 active galactic nucleus (AGN) sample, using high signal-to-noise ratio (S/N>20) spectra of the counterparts of the ROSAT/2RXS sources in the footprint of the SDSS-IV/SPIDERS (Spectroscopic IDentification of eROSITA Sources) programme. The final sample contains 2100 sources. It significantly extends the redshift and luminosity ranges (z ∼ 0.01-0.80 and L_{0.1-2.4 keV} ∼ 2.0 × 10^{41}-1.0 × 10^{46} erg s^{-1}) used so far in this kind of analysis. By means of a principal component analysis, we derive eigenvector (EV) 1 and 2 in an eleven-dimensional optical and X-ray parameter space, which are consistent with previous results. The validity of the correlations of the Eddington ratio L/LEdd with EV1 and the black hole mass with EV2 is strongly confirmed. These results imply that L/LEdd and black hole mass are related to the diversity of the optical properties of Type 1 AGNs. Investigating the relation of the width and asymmetry of H β and the relative strength of the iron emission r_{Fe II}, we show that our analysis supports the presence of a distinct kinematic region: the very broad line region. Furthermore, comparing sources with a red-asymmetric broad H β emission line to sources for which it is blue asymmetric, we find an intriguing difference in the correlation of the Fe II and the continuum emission strengths. We show that this contrasting behaviour is consistent with a flattened, stratified model of the broad-line region, in which the Fe II-emitting region is shielded from the central source.


RU-D
(383)Three-dimensional simulations of clump formation in stellar wind collisions
  • D. Calderón,
  • J. Cuadra,
  • M. Schartmann,
  • A. Burkert,
  • J. Prieto
  • +1
Monthly Notices of the Royal Astronomical Society (03/2020) doi:10.1093/mnras/staa090
abstract + abstract -

The inner parsec of our Galaxy contains tens of Wolf-Rayet stars whose powerful outflows are constantly interacting while filling the region with hot, diffuse plasma. Theoretical models have shown that, in some cases, the collision of stellar winds can generate cold, dense material in the form of clumps. However, their formation process and properties are not well understood yet. In this work, we present, for the first time, a statistical study of the clump formation process in unstable wind collisions. We study systems with dense outflows (∼ 10^{-5} M_{⊙ } yr^{-1}), wind speeds of 500-1500 km s^{-1}, and stellar separations of ∼20-200 au. We develop three-dimensional high-resolution hydrodynamical simulations of stellar wind collisions with the adaptive-mesh refinement grid-based code RAMSES. We aim at characterizing the initial properties of clumps that form through hydrodynamic instabilities, mostly via the non-linear thin-shell instability (NTSI). Our results confirm that more massive clumps are formed in systems whose winds are close to the transition between the radiative and adiabatic regimes. Increasing either the wind speed or the degree of asymmetry increases the dispersion of the clump mass and ejection speed distributions. Nevertheless, the most massive clumps are very light (∼10-3-10^{-2} M_{\oplus }), about three orders of magnitude less massive than theoretical upper limits. Applying these results to the Galactic Centre, we find that clumps formed through the NTSI should not be heavy enough either to affect the thermodynamic state of the region or to survive for long enough to fall on to the central supermassive black hole.


CN-7
RU-A
(382)Fast neutrino flavor instability in the neutron-star convection layer of three-dimensional supernova models
  • Robert Glas,
  • H. -Thomas Janka,
  • Francesco Capozzi,
  • Manibrata Sen,
  • Basudeb Dasgupta
  • +2
  • Alessandro Mirizzi,
  • Günter Sigl
  • (less)
Physical Review D (03/2020) doi:10.1103/PhysRevD.101.063001
abstract + abstract -

It has been speculated for a long time that neutrinos from a supernova (SN) may undergo fast flavor conversions near the collapsed stellar core. We perform a detailed study of this intriguing possibility, for the first time analyzing two time-dependent state-of-the-art three-dimensional (3D) SN models of 9 M and 20 M from recent papers of Glas et al. Both models were computed with multidimensional three-flavor neutrino transport based on a two-moment solver, and both exhibit the presence of the so-called lepton-number emission self-sustained asymmetry (LESA). The transport solution does not provide the angular distributions of the flavor-dependent neutrino fluxes, which are crucial to track the fast flavor instability. To overcome this limitation, we use a recently proposed approach based on the angular moments of the energy-integrated electron lepton-number distribution up to second order, i.e., angle-energy integrals of the difference between νe and ν¯e phase-space distributions multiplied by corresponding powers of the unit vector of the neutrino velocity. With this method we find the possibility of fast neutrino flavor instability at radii smaller than ∼20 km , which is well interior to the neutrinosphere where neutrinos are still in the diffusive and near-equilibrium regime. Our results confirm recent observations in a two-dimensional (2D) (axisymmetric) SN model and in 2D and 3D models with a fixed matter background, which were computed with Boltzmann neutrino transport. However, the flavor unstable locations are not isolated points as discussed previously, but thin skins surrounding volumes where ν¯e are more abundant than νe. These volumes grow with time and appear first in the convective layer of the proto-neutron star (PNS), where a decreasing electron fraction and high temperatures favor the occurrence of regions with negative neutrino chemical potential. Since the electron fraction remains higher in the LESA dipole direction, where convective lepton-number transport out from the nonconvective PNS core slows down the deleptonization, flavor unstable conditions become more widespread in the opposite hemisphere. This interesting phenomenon deserves further investigation, since its impact on SN modeling and possible consequences for SN dynamics and neutrino observations are presently unclear.


(381)Type Ic supernova of a 22 M<SUB>⊙</SUB> progenitor
  • Jacob Teffs,
  • Thomas Ertl,
  • Paolo Mazzali,
  • Stephan Hachinger,
  • Thomas Janka
Monthly Notices of the Royal Astronomical Society (03/2020) doi:10.1093/mnras/staa123
abstract + abstract -

Type Ic supernovae (SNe Ic) are a sub-class of core-collapse SNe that exhibit no helium or hydrogen lines in their spectra. Their progenitors are thought to be bare carbon-oxygen cores formed during the evolution of massive stars that are stripped of their hydrogen and helium envelopes sometime before collapse. SNe Ic present a range of luminosities and spectral properties, from luminous GRB-SNe with broad-lined spectra to less luminous events with narrow-line spectra. Modelling SNe Ic reveals a wide range of both kinetic energies, ejecta masses, and 56Ni masses. To explore this diversity and how it comes about, light curves and spectra are computed from the ejecta following the explosion of an initially 22 M progenitor that was artificially stripped of its hydrogen and helium shells, producing a bare CO core of ∼5 M, resulting in an ejected mass of ∼4 M, which is an average value for SNe Ic. Four different explosion energies are used that cover a range of observed SNe. Finally, 56Ni and other elements are artificially mixed in the ejecta using two approximations to determine how element distribution affects light curves and spectra. The combination of different explosion energy and degree of mixing produces spectra that roughly replicate the distribution of near-peak spectroscopic features of SNe Ic. High explosion energies combined with extensive mixing can produce red, broad-lined spectra, while minimal mixing and a lower explosion energy produce bluer, narrow-lined spectra.


(380)The Mira-Titan Universe. III. Emulation of the Halo Mass Function
  • Sebastian Bocquet,
  • Katrin Heitmann,
  • Salman Habib,
  • Earl Lawrence,
  • Thomas Uram
  • +3
  • Nicholas Frontiere,
  • Adrian Pope,
  • Hal Finkel
  • (less)
abstract + abstract -

We construct an emulator for the halo mass function over group and cluster mass scales for a range of cosmologies, including the effects of dynamical dark energy and massive neutrinos. The emulator is based on the recently completed Mira-Titan Universe suite of cosmological N-body simulations. The main set of simulations spans 111 cosmological models with 2.1 Gpc boxes. We extract halo catalogs in the redshift range z = [0.0, 2.0] and for masses . The emulator covers an eight-dimensional hypercube spanned by {, , , σ 8, h, n s , w 0, w a }; spatial flatness is assumed. We obtain smooth halo mass functions by fitting piecewise second-order polynomials to the halo catalogs and employ Gaussian process regression to construct the emulator while keeping track of the statistical noise in the input halo catalogs and uncertainties in the regression process. For redshifts z ≲ 1, the typical emulator precision is better than 2% for and <10% for . For comparison, fitting functions using the traditional universal form for the halo mass function can be biased at up to 30% at for z = 0. Our emulator is publicly available at github.com/SebastianBocquet/MiraTitanHMFemulator.


RU-C
(379)Physical parameter space of bimetric theory and SN1a constraints
  • Marvin Lüben,
  • Angnis Schmidt-May,
  • Jochen Weller
abstract + abstract -

Bimetric theory describes a massless and a massive spin-2 field with fully non-linear (self-)interactions. It has a rich phenomenology and has been successfully tested with several data sets. However, the observational constraints have not been combined in a consistent framework, yet. We propose a parametrization of bimetric solutions in terms of the effective cosmological constant Λ and the mass mFP of the spin-2 field as well as its coupling strength to ordinary matter &baralpha;. This simplifies choosing priors in statistical analysis and allows to directly constrain these parameters with observational data not only from local systems but also from cosmology. By identifying the physical vacuum of bimetric theory these parameters are uniquely determined. We work out the new parametrization for various submodels and present the implied consistency constraints on the physical parameter space. As an application we derive observational constraints from SN1a on the physical parameters. We find that a large portion of the physical parameter space is in perfect agreement with current supernova data including self-accelerating models with a heavy spin-2 field.


RU-C
(378)Validation of Selection Function, Sample Contamination and Mass Calibration in Galaxy Cluster Samples
  • S. Grandis,
  • M. Klein,
  • J.J. Mohr,
  • S. Bocquet,
  • M. Paulus
  • +67
  • T.M.C. Abbott,
  • M. Aguena,
  • S. Allam,
  • J. Annis.,
  • B.A. Benson,
  • E. Bertin,
  • S. Bhargava,
  • D. Brooks,
  • D.L. Burke,
  • A. Carnero Rosell,
  • M. Carrasco Kind,
  • J. Carretero,
  • R. Capasso,
  • M. Costanzi,
  • L.N. da Costa,
  • J. De Vicente,
  • S. Desai,
  • J.P. Dietrich,
  • P. Doel,
  • T.F. Eifler,
  • A.E. Evrard,
  • B. Flaugher,
  • P. Fosalba,
  • J. Frieman,
  • J. García-Bellido,
  • E. Gaztanaga,
  • D.W. Gerdes,
  • D. Gruen,
  • R.A. Gruendl,
  • J. Gschwend,
  • G. Gutierrez,
  • W.G. Hartley,
  • S.R. Hinton,
  • D.L. Hollowood,
  • K. Honscheid,
  • D.J. James,
  • T. Jeltema,
  • K. Kuehn,
  • N. Kuropatkin,
  • M. Lima,
  • M.A.G. Maia,
  • J.L. Marshall,
  • P. Melchior,
  • F. Menanteau,
  • R. Miquel,
  • R.L.C. Ogando,
  • A. Palmese,
  • F. Paz-Chinchón,
  • A.A. Plazas,
  • A.K. Romer,
  • A. Roodman,
  • E. Sanchez,
  • A. Saro,
  • V. Scarpine,
  • M. Schubnell,
  • S. Serrano,
  • E. Sheldon,
  • M. Smith,
  • A.A. Stark,
  • E. Suchyta,
  • M.E.C. Swanson,
  • G. Tarle,
  • D. Thomas,
  • D.L. Tucker,
  • T.N. Varga,
  • J. Weller,
  • R. Wilkinson
  • (less)
Mon.Not.Roy.Astron.Soc. (02/2020) e-Print:2002.10834 doi:10.1093/mnras/staa2333
abstract + abstract -

We construct and validate the selection function of the MARD-Y3 galaxy cluster sample. This sample was selected through optical follow-up of the 2nd ROSAT faint source catalogue with Dark Energy Survey year 3 data. The selection function is modelled by combining an empirically constructed X-ray selection function with an incompleteness model for the optical follow-up. We validate the joint selection function by testing the consistency of the constraints on the X-ray flux–mass and richness–mass scaling relation parameters derived from different sources of mass information: (1) cross-calibration using South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) clusters, (2) calibration using number counts in X-ray, in optical and in both X-ray and optical while marginalizing over cosmological parameters, and (3) other published analyses. We find that the constraints on the scaling relation from the number counts and SPT-SZ cross-calibration agree, indicating that our modelling of the selection function is adequate. Furthermore, we apply a largely cosmology independent method to validate selection functions via the computation of the probability of finding each cluster in the SPT-SZ sample in the MARD-Y3 sample and vice versa. This test reveals no clear evidence for MARD-Y3 contamination, SPT-SZ incompleteness or outlier fraction. Finally, we discuss the prospects of the techniques presented here to limit systematic selection effects in future cluster cosmological studies.


(377)Decay and electromagnetic production of strongly coupled quarkonia in pNRQCD
  • Nora Brambilla,
  • Hee Sok Chung,
  • Daniel Müller,
  • Antonio Vairo
abstract + abstract -

We improve the pNRQCD approach to annihilation processes of heavy quarkonium and make first pNRQCD predictions for exclusive electromagnetic production of heavy quarkonium. We consider strongly coupled quarkonia, i.e., quarkonia that are not Coulombic bound states. Possible strongly coupled quarkonia include excited charmonium and bottomonium states. For these, pNRQCD provides expressions for the decay and exclusive electromagnetic production NRQCD matrix elements that depend on the wavefunctions at the origin and few universal gluon field correlators. We compute electromagnetic decay widths and exclusive production cross sections, and inclusive decay widths into light hadrons for P -wave quarkonia at relative order v$^{2}$ and leading order, respectively. We also compute the decay widths of 2S and 3S bottomonium states into lepton pairs and their ratios with the inclusive widths into light hadrons at relative order v$^{2}$.


(376)Dalitz-plot decomposition for three-body decays
  • M. Mikhasenko,
  • M. Albaladejo,
  • Ł. Bibrzycki,
  • C. Fernández-Ramírez,
  • V. Mathieu
  • +6
  • S. Mitchell,
  • M. Pappagallo,
  • A. Pilloni,
  • D. Winney,
  • T. Skwarnicki,
  • A. P. Szczepaniak
  • (less)
Physical Review D (02/2020) doi:10.1103/PhysRevD.101.034033
abstract + abstract -

We present a general formalism to write the decay amplitude for multibody reactions with explicit separation of the rotational degrees of freedom, which are well controlled by the spin of the decay particle, and dynamic functions on the subchannel invariant masses, which require modeling. Using the three-particle kinematics we demonstrate the proposed factorization, named the Dalitz-plot decomposition. The Wigner rotations, which are subtle factors needed by the isobar modeling in the helicity framework, are simplified with the proposed decomposition. Consequently, we are able to provide them in an explicit form suitable for the general case of arbitrary spins. The only unknown model-dependent factors are the isobar line shapes that describe the subchannel dynamics. The advantages of the new decomposition are shown through three examples relevant for the recent discovery of the exotic charmonium candidate Zc(4430 ), the pentaquarks Pc, and the intriguing Λc+→p K-π+ decay.


MIAPbP
RU-D
(375)Toward Early-type Eclipsing Binaries as Extragalactic Milestones. II. NLTE Spectral Analysis and Stellar Parameters of the Detached O-type System OGLE-LMC-ECL-06782 in the LMC
  • Mónica Taormina,
  • Rolf-Peter Kudritzki,
  • Joachim Puls,
  • Bogumił Pilecki,
  • Eva Sextl
  • +3
  • G. Pietrzyński,
  • Miguel A. Urbaneja,
  • Wolfgang Gieren
  • (less)
The Astrophysical Journal (02/2020) doi:10.3847/1538-4357/ab6bd0
abstract + abstract -

We combine the NLTE spectral analysis of the detached O-type eclipsing binary OGLE-LMC-ECL-06782 with the analysis of the radial velocity curve and light curve to measure an independent distance to the Large Magellanic Cloud (LMC). In our spectral analysis we study composite spectra of the system at quadrature and use the information from radial velocity and light curve about stellar gravities, radii, and component flux ratio to derive effective temperature, reddening, extinction, and intrinsic surface brightness. We obtain a distance modulus to the LMC of m - M = 18.53 ± 0.04 mag. This value is 0.05 mag larger than the precision distance obtained recently from the analysis of a large sample of detached, long period late spectral type eclipsing binaries but agrees within the margin of the uncertainties. We also determine the surface brightnesses of the system components and find good agreement with the published surface brightness-color relationship. A comparison of the observed stellar parameters with the prediction of stellar evolution based on the MESA stellar evolution code shows reasonable agreement, but requires a reduction of the internal angular momentum transport to match the observed rotational velocities.


MIAPbP
(374)Beauty at High Precision / Sensitivity
  • Chris Quigg
arXiv e-prints (02/2020) e-Print:2002.08292
abstract + abstract -

Origins of contemporary $B$-physics. Mesons with beauty and charm. Stable tetraquarks? Flavor and the problem of identity. Top matters. Electroweak symmetry breaking and the Higgs sector. Future instruments.


(373)Eclectic flavor groups
  • Hans Peter Nilles,
  • Saúl Ramos-Sánchez,
  • Patrick K. S. Vaudrevange
Journal of High Energy Physics (02/2020) doi:10.1007/JHEP02(2020)045
abstract + abstract -

The simultaneous study of top-down and bottom-up approaches to modular flavor symmetry leads necessarily to the concept of eclectic flavor groups. These are non-trivial products of modular and traditional flavor symmetries that exhibit the phenomenon of local flavor enhancement in moduli space. We develop methods to determine the eclectic flavor groups that can be consistently associated with a given traditional flavor symmetry. Applying these methods to a large family of prominent traditional flavor symmetries, we try to identify potential candidates for realistic eclectic flavor groups and show that they are relatively rare. Model building with finite modular flavor symmetries thus appears to be much more restrictive than previously thought.


CN-4
MIAPbP
RU-D
(372)A Simple Unified Spectroscopic Indicator of Stellar Luminosity: The Extended Flux-weighted Gravity-Luminosity Relationship
  • Rolf-Peter Kudritzki,
  • Miguel A. Urbaneja,
  • Hans-Walter Rix
The Astrophysical Journal (02/2020) doi:10.3847/1538-4357/ab67c3
abstract + abstract -

We show that for a wide range of stellar masses, from 0.3 to 20 M, and for evolutionary phases from the main sequence to the beginning of the red giant stage, the stellar flux-weighted gravity, gF ≅ g/ ${T}_{\mathrm{eff}}^{4}$ , is tightly correlated with absolute bolometric magnitude ${M}_{\mathrm{bol}}$ . Such a correlation is predicted by stellar evolution theory. We confirm this relation observationally, using a sample of 445 stars with precise stellar parameters. It holds over 17 stellar magnitudes from ${M}_{\mathrm{bol}}$ = 9.0 to -8.0 mag with a scatter of 0.17 mag above ${M}_{\mathrm{bol}}$ = -3.0 and 0.29 mag below this value. We then test the relation with 2.2 million stars with 6.5 mag ≥ ${M}_{\mathrm{bol}}$ ≥ 0.5 mag, where "mass-produced" but robust $\mathrm{log}\,g$ , ${T}_{{\rm{e}}{\rm{f}}{\rm{f}}},$ and ${M}_{\mathrm{bol}}$ from LAMOST DR5 and Gaia DR2 are available. We find that the same relation holds with a scatter of ∼0.2 mag for single stars offering a simple spectroscopic distance estimate good to ∼10%.


CN-5
RU-D
(371)Large-scale Mixing in a Violent Oxygen-Neon Shell Merger Prior to a Core-collapse Supernova
  • Naveen Yadav,
  • Bernhard Müller,
  • Hans Thomas Janka,
  • Tobias Melson,
  • Alexander Heger
The Astrophysical Journal (02/2020) doi:10.3847/1538-4357/ab66bb
abstract + abstract -

We present a 7 minute long 4π-3D simulation of a shell merger event in a nonrotating 18.88 ${M}_{\odot }$ M ⊙ supernova progenitor before the onset of gravitational collapse. The key motivation is to capture the large-scale mixing and asymmetries in the wake of the shell merger before collapse using a self-consistent approach. The 4π geometry is crucial, as it allows us to follow the growth and evolution of convective modes on the largest possible scales. We find significant differences between the kinematic, thermodynamic, and chemical evolution of the 3D and 1D models. The 3D model shows vigorous convection leading to more efficient mixing of nuclear species. In the 3D case, the entire oxygen shell attains convective Mach numbers of ≈0.1, whereas in the 1D model, the convective velocities are much lower, and there is negligible overshooting across convective boundaries. In the 3D case, the convective eddies entrain nuclear species from the neon (and carbon) layers into the deeper part of the oxygen-burning shell, where they burn and power a violent convection phase with outflows. This is a prototypical model of a convective-reactive system. Due to the strong convection and resulting efficient mixing, the interface between the neon layer and the silicon-enriched oxygen layer disappears during the evolution, and silicon is mixed far out into the merged oxygen/neon shell. Neon entrained inward by convective downdrafts burns, resulting in lower neon mass in the 3D model compared to the 1D model at the time of collapse. In addition, the 3D model develops remarkable large-scale, large-amplitude asymmetries, which may have important implications for the impending gravitational collapse and subsequent explosion.


RU-A
(370)Quark-lepton connections in Z' mediated FCNC processes: gauge anomaly cancellations at work
  • Jason Aebischer,
  • Andrzej J. Buras,
  • Maria Cerdà-Sevilla,
  • Fulvia De Fazio
Journal of High Energy Physics (02/2020) doi:10.1007/JHEP02(2020)183
abstract + abstract -

We consider scenarios with a heavy Z' gauge boson with flavour non-universal quark and lepton couplings with the goal to illustrate how the cancellation of gauge anomalies generated by the presence of an additional U(1)' gauge symmetry would imply correlations between FCNC processes within the quark sector, within the lepton sector and most interestingly between quark flavour and lepton flavour violating processes. To this end we present simple scenarios with only left-handed flavour-violating Z' couplings and those in which also right-handed flavour-violating couplings are present. The considered scenarios are characterized by a small number of free parameters but in contrast to gauge anomaly cancellation in the Standard Model, in which it takes place separately within each generation, in our scenarios anomaly cancellation involves simultaneously quarks and leptons of all three generations. Our models involve, beyond the ordinary quarks and leptons, three heavy right-handed neutrinos. The models with only left-handed FCNCs of Z' involve beyond gZ' and MZ' two real parameters characterizing the charges of all fermions under the U(1)' gauge symmetry and the CKM and PMNS ones in the quark and lepton sectors, respectively. The models with the right-handed FCNCs of Z' involve few additional parameters. Imposing constraints from well measured ΔF = 2 observables we identify a number of interesting correlations that involve e.g. ɛ'/ɛ, Bs,d→ μ+μ-, B → K(K*)ℓ+-, K+→π+ν ν ¯,KL→π0ν ν ¯ and purely lepton flavour violating decays like μ → eγ, μ → 3e, τ → 3μ and μ - e conversion among others. Also (g - 2)μ,e are considered. The impact of the experimental μ → eγ, μ → 3e and in particular μ - e conversion bounds on rare K and B decays is emphasized.


RU-D
(369)The Explosion of Helium Stars Evolved with Mass Loss
  • T. Ertl,
  • S. E. Woosley,
  • Tuguldur Sukhbold,
  • H. -T. Janka
The Astrophysical Journal (02/2020) doi:10.3847/1538-4357/ab6458
abstract + abstract -

Light curves, explosion energies, and remnant masses are calculated for a grid of supernovae resulting from massive helium stars that have been evolved including mass loss. These presupernova stars should approximate the results of binary evolution for stars in interacting systems that lose their envelopes close to the time of helium core ignition. Initial helium star masses are in the range 2.5-40 M, which corresponds to main-sequence masses of about 13-90 M. Common SNe Ib and Ic result from stars whose final masses are approximately 2.5-5.6 M. For heavier stars, a large fraction of collapses lead to black holes, though there is an island of explodability for presupernova masses near 10 M. The median neutron star mass in binaries is 1.35-1.38 M, and the median black hole mass is between 9 and 11 M. Even though black holes less massive than 5 M are rare, they are predicted down to the maximum neutron star mass. There is no empty "gap," only a less populated mass range. For standard assumptions regarding the explosions and nucleosynthesis, the models predict light curves that are fainter than the brighter common SNe Ib and Ic. Even with a very liberal but physically plausible increase in 56Ni production, the highest-energy models are fainter than 1042.6 erg s-1 at peak, and very few approach that limit. The median peak luminosity ranges from 1042.0 to 1042.3 erg s-1. Possible alternatives to the standard neutrino-powered and radioactive-illuminated models are explored. Magnetars are a promising alternative. Several other unusual varieties of SNe I at both high and low mass are explored.


RU-A
(368)Bayesian analysis of b→sμ+μ− Wilson coefficients using the full angular distribution of Λb→Λ(→pπ−)μ+μ− decays
  • Thomas Blake,
  • Stefan Meinel,
  • Danny van Dyk
abstract + abstract -

Following updated and extended measurements of the full angular distribution of the decay Λb→Λ(→pπ−)μ+μ− by the LHCb collaborations, as well as a new measurement of the Λ→pπ− decay asymmetry parameter by the BESIII collaboration, we study the impact of these results on searches for non-standard effects in exclusive b→sμ+μ− decays. To this end, we constrain the Wilson coefficients 9 and 10 of the numerically leading dimension-six operators in the weak effective Hamiltonian, in addition to the relevant nuisance parameters. In stark contrast to previous analyses of this decay mode, the changes in the updated experimental results lead us to find very good compatibility with both the Standard Model and with the b→sμ+μ− anomalies observed in rare B-meson decays. We provide a detailed analysis of the impact of the partial angular distribution, the full angular distribution, and the Λb→Λμ+μ− branching fraction on the Wilson coefficients. In this process, we are also able to constrain the size of the production polarization of the Λb baryon at LHCb.


MIAPbP
(367)Present-day mass-metallicity relation for galaxies using a new electron temperature method
  • R. M. Yates,
  • P. Schady,
  • T. -W. Chen,
  • T. Schweyer,
  • P. Wiseman
Astronomy and Astrophysics (02/2020) doi:10.1051/0004-6361/201936506
abstract + abstract -


Aims: We investigate electron temperature (Te) and gas-phase oxygen abundance (ZTe) measurements for galaxies in the local Universe (z < 0.25). Our sample comprises spectra from a total of 264 emission-line systems, ranging from individual HII regions to whole galaxies, including 23 composite HII regions from star-forming main sequence galaxies in the MaNGA survey.
Methods: We utilise 130 of these systems with directly measurable Te(OII) to calibrate a new metallicity-dependent Te(OIII)-Te(OII) relation that provides a better representation of our varied dataset than existing relations from the literature. We also provide an alternative Te(OIII)-Te(NII) calibration. This new Te method is then used to obtain accurate ZTe estimates and form the mass - metallicity relation (MZR) for a sample of 118 local galaxies.
Results: We find that all the Te(OIII)-Te(OII) relations considered here systematically under-estimate ZTe for low-ionisation systems by up to 0.6 dex. We determine that this is due to such systems having an intrinsically higher O+ abundance than O++ abundance, rendering ZTe estimates based only on [OIII] lines inaccurate. We therefore provide an empirical correction based on strong emission lines to account for this bias when using our new Te(OIII)-Te(OIII) and Te(OIII)-Te(NII) relations. This allows for accurate metallicities (1σ = 0.08 dex) to be derived for any low-redshift system with an [OIII]λ4363 detection, regardless of its physical size or ionisation state. The MZR formed from our dataset is in very good agreement with those formed from direct measurements of metal recombination lines and blue supergiant absorption lines, in contrast to most other Te-based and strong-line-based MZRs. Our new Te method therefore provides an accurate and precise way of obtaining ZTe for a large and diverse range of star-forming systems in the local Universe.


(366)Measurement of Void Bias Using Separate Universe Simulations
  • Kwan Chuen Chan,
  • Yin Li,
  • Matteo Biagetti,
  • Nico Hamaus
The Astrophysical Journal (02/2020) doi:10.3847/1538-4357/ab64ec
abstract + abstract -

Cosmic voids are biased tracers of the large-scale structure of the universe. Separate universe simulations (SUS) enable accurate measurements of this biasing relation by implementing the peak-background split (PBS). In this work, we apply the SUS technique to measure the void bias parameters. We confirm that the PBS argument works well for underdense tracers. The response of the void size distribution depends on the void radius. For voids larger (smaller) than the size at the peak of the distribution, the void abundance responds negatively (positively) to a long wavelength mode. The linear bias from the SUS is in good agreement with the cross power spectrum measurement on large scales. Using the SUS, we have detected the quadratic void bias for the first time in simulations. We find that b2 is negative when the magnitude of b1 is small, and that it becomes positive and increases rapidly when $| {b}_{1}| $ increases. We compare the results from voids identified in the halo density field with those from the dark matter distribution, and find that the results are qualitatively similar, but the biases generally shift to the larger voids sizes.


MIAPbP
(365)Continuous renormalization group β function from lattice simulations
  • Anna Hasenfratz,
  • Oliver Witzel
Physical Review D (02/2020) doi:10.1103/PhysRevD.101.034514
abstract + abstract -

We present a real-space renormalization group transformation with continuous scale change to calculate the continuous renormalization group β function in nonperturbative lattice simulations. Our method is motivated by the connection between Wilsonian renormalization group and the gradient flow transformation. It does not rely on the perturbative definition of the renormalized coupling and is also valid at nonperturbative fixed points. Although our method requires an additional extrapolation compared to traditional step scaling calculations, it has several advantages which compensates for this extra step even when applied in the vicinity of the perturbative fixed point. We illustrate our approach by calculating the β function of 2-flavor QCD and show that lattice predictions from individual lattice ensembles, even without the required continuum and finite volume extrapolations, can be very close to the result of the full analysis. Thus our method provides a nonperturbative framework and intuitive understanding into the structure of strongly coupled systems, in addition to being complementary to existing lattice determinations.


MIAPbP
(364)Probing the C P nature of the top quark Yukawa at hadron colliders
  • Darius A. Faroughy,
  • Jernej F. Kamenik,
  • Nejc Košnik,
  • Aleks Smolkovič
Journal of High Energy Physics (02/2020) doi:10.1007/JHEP02(2020)085
abstract + abstract -

We analyze the prospects of probing the C P -odd i κ ∼t ¯γ 5th interaction at the LHC and its projected upgrades, the high-luminosity and high-energy LHC, directly using associated on-shell Higgs boson and top quark or top quark pair production. To this end we first construct a C P -odd observable based on top quark polarization in Wb → th scattering with optimal linear sensitivity to κ ∼. For the corresponding hadronic process pp → thj we present a method of extracting the phase-space dependent weight function that allows to retain close to optimal sensitivity to κ ∼. We project future sensitivity to the signal in pp → t(→ ℓ


MIAPbP
(363)Circumnavigating collinear superspace
  • Timothy Cohen,
  • Gilly Elor,
  • Andrew J. Larkoski,
  • Jesse Thaler
Journal of High Energy Physics (02/2020) doi:10.1007/JHEP02(2020)156
abstract + abstract -

In this paper, we extend the collinear superspace formalism to include the full range of N = 1 supersymmetric interactions. Building on the effective field theory rules developed in a companion paper — Navigating Collinear Superspace [1] — we construct collinear superspace Lagrangians for theories with non-trivial F- and D-term auxiliary fields. For (massless) Wess-Zumino models, the key ingredient is a novel type of Grassmann-valued supermultiplet whose lowest component is a (non-propagating) fermionic degree of freedom. For gauge theories coupled to charged chiral matter, the key ingredient is a novel type of vector superfield whose lowest component is a non-propagating gauge potential. This unique vector superfield is used to construct a gauge-covariant derivative; while such an object does not appear in the standard full superspace formalism, it is crucial for modeling gauge interactions when the theory is expres sed on a collinear slice. This brings us full circle, by showing that all types of N = 1 theories in four dimensions can beconstructed in collinear superspace from purely infrared considerations. We speculate that supersymmetric theories with N > 1 could also be implemented using similar collinear superspace constructions.


MIAPbP
(362)From boundary data to bound states. Part II. Scattering angle to dynamical invariants (with twist)
  • Gregor Kälin,
  • Rafael A. Porto
Journal of High Energy Physics (02/2020) doi:10.1007/JHEP02(2020)120
abstract + abstract -

We recently introduced in [9] a boundary-to-bound dictionary between gravitational scattering data and observables for bound states of non-spinning bodies. In this paper, we elaborate further on this holographic map. We start by deriving the following — remarkably simple — formula relating the periastron advance to the scattering angle: ΔΦ (" separators=",J E )=χ (" separators=",J E )+χ (" separators=",-J E ), via analytic continuation in angular momentum and binding energy. Using explicit expressions from [9], we confirm its validity to all orders in the Post-Minkowskian (PM) expansion. Furthermore, we reconstruct the radial action for the bound state directly from the knowledge of the scattering angle. The radial action enables us to write compact expressions for dynamical invariants in terms of the deflection angle to all PM orders, which can also be written as a function of the PM-expanded amplitude. As an example, we reproduce our result in [9] for the periastron advance, and compute the radial and azimuthal frequencies and redshift variable to two-loops. Agreement is found in the overlap between PM and Post-Newtonian (PN) schemes. Last but not least, we initiate the study of our dictionary including spin. We demonstrate that the same relation between deflection angle and periastron advance applies for aligned-spin contributions, with J the (canonical) total angular momentum. Explicit checks are performed to display perfect agreement using state-of-the-art PN results in the literature. Using the map between test- and two-body dynamics, we also compute the periastron advance up to quadratic order in spin, to one-loop and to all orders in velocity. We conclude with a discussion on the generalized `impetus formula' for spinning bodies and black holes as `elementary particles'. Our findings here and in [9] imply that the deflection angle already encodes vast amount of physical information for bound orbits, encouraging independent derivations using numerical and/or self-force methodologies.


MIAPbP
(361)Galaxy assembly bias of central galaxies in the Illustris simulation
  • Xiaoju Xu,
  • Zheng Zheng
Monthly Notices of the Royal Astronomical Society (02/2020) doi:10.1093/mnras/staa009
abstract + abstract -

Galaxy assembly bias, the correlation between galaxy properties and halo properties at fixed halo mass, could be an important ingredient in halo-based modelling of galaxy clustering. We investigate the central galaxy assembly bias by studying the relation between various galaxy and halo properties in the Illustris hydrodynamic galaxy formation simulation. Galaxy stellar mass M* is found to have a tighter correlation with peak maximum halo circular velocity Vpeak than with halo mass Mh. Once the correlation with Vpeak is accounted for, M* has nearly no dependence on any other halo assembly variables. The correlations between galaxy properties related to star formation history and halo assembly properties also show a cleaner form as a function of Vpeak than as a function of Mh, with the main correlation being with halo formation time and to a less extent halo concentration. Based on the galaxy-halo relation, we present a simple model to relate the bias factors of a central galaxy sample and the corresponding halo sample, both selected based on assembly-related properties. It is found that they are connected by the correlation coefficient of the galaxy and halo properties used to define the two samples, which provides a reasonable description for the samples in the simulation and suggests a simple prescription to incorporate galaxy assembly bias into the halo model. By applying the model to the local galaxy clustering measurements in Lin et al., we infer that the correlation between star formation history or specific star formation rate and halo formation time is consistent with being weak.


MIAPbP
(360)|V<SUB>ub</SUB>| determination and testing of lepton flavour universality in semileptonic B<SUB>c</SUB> → D<SUP>(∗)</SUP> decays
  • Domagoj Leljak,
  • Blaženka Melić
Journal of High Energy Physics (02/2020) doi:10.1007/JHEP02(2020)171
abstract + abstract -

In light of prospects for measurements of Bc → D(∗)lv decays in the upcoming Upgrade II of the LHC, we show that by using calculated Bc → D(∗) form factors a competitive extraction of the |Vub| CKM matrix element from the Bc→Dμ v¯μ decay might be possible. To minimize experimental and theoretical uncertainties we provide the ratio |Vub|/|Vcb| by normalizing the Bc→D(∗)μ v¯μ to Bc→J /ψμ v¯μ decay. We also briefly examine the suggestion to extract |Vub|/|Vcs| from the theoretically interesting ratio of Bc→D0e v¯e and Bc→Bse v¯e decay rates in the zero-recoil limit. With the present average value of |Vub|, the predicted branching ratios are estimated to be BR (Bc→D0μ ν¯μ )=(2.4 ±0.4 ).10-5 and BR (Bc→Dμ ν¯μ )=(7 ±3 ).10-5, and the semileptonic ratios for testing the lepton flavour universality in these Bc decays are Rc(D0) = 0.64 ± 0.05 and Rc(D) = 0.55 ± 0.05. We also provide q2 distributions and various angular observables of Bc→ D(∗)lν decays.


MIAPbP
(359)Effective field theory and scalar extensions of the top quark sector
  • Christoph Englert,
  • Peter Galler,
  • Chris D. White
Physical Review D (02/2020) doi:10.1103/PhysRevD.101.035035
abstract + abstract -

Effective field theory (EFT) approaches are widely used at the Large Hadron Collider (LHC), such that it is important to study their validity and ease of matching to specific new physics models. In this paper, we consider an extension of the Standard Model (SM) in which a top quark couples to a new heavy scalar. We find the dimension six operators generated by this theory at low energy and match the EFT to the full theory up to the next-to-leading order (NLO) precision in the simplified model coupling. We then examine the range of validity of the EFT description in top pair production, finding excellent validity even if the scalar mass is only slightly above LHC energies, provided NLO corrections are included. In the absence of the latter, the LO EFT overestimates kinematic distributions, such that overoptimistic constraints on beyond the Standard Model (BSM) contributions are obtained. We next examine the constraints on the EFT and full models that are expected to be obtained from both top pair and four top production at the LHC, finding for low scalar masses that both processes show similar exclusion power. However, for larger masses, estimated LHC uncertainties push constraints into the nonperturbative regime, where the full model is difficult to analyze, and thus is not perturbatively matchable to the EFT. This highlights the necessity to improve uncertainties of SM hypotheses in top final states.


MIAPbP
(358)Interpretation of the LHCb P<SUB>c</SUB> States as Hadronic Molecules and Hints of a Narrow P<SUB>c</SUB>(4380 )
  • Meng-Lin Du,
  • Vadim Baru,
  • Feng-Kun Guo,
  • Christoph Hanhart,
  • Ulf-G. Meißner
  • +2
Physical Review Letters (02/2020) doi:10.1103/PhysRevLett.124.072001
abstract + abstract -

Three hidden-charm pentaquark Pc states, Pc(4312 ), Pc(4440 ), and Pc(4457 ) were revealed in the Λb0→J /ψ p K- process measured by LHCb using both run I and run II data. Their nature is under lively discussion, and their quantum numbers have not been determined. We analyze the J /ψ p invariant mass distributions under the assumption that the crossed-channel effects provide a smooth background. For the first time, such an analysis is performed employing a coupled-channel formalism with the scattering potential involving both one-pion exchange as well as short-range operators constrained by heavy quark spin symmetry. We find that the data can be well described in the hadronic molecular picture, which predicts seven Σc(*)D¯(*) molecular states in two spin multiplets, such that the Pc(4312 ) is mainly a ΣcD ¯ bound state with JP=1 /2-, while Pc(4440 ) and Pc(4457 ) are ΣcD¯* bound states with quantum numbers 3 /2- and 1 /2-, respectively. We also show that there is evidence for a narrow Σc*D ¯ bound state in the data which we call Pc(4380 ), different from the broad one reported by LHCb in 2015. With this state included, all predicted ΣcD ¯, Σc*D ¯, and ΣcD¯* hadronic molecules are seen in the data, while the missing three Σc*D¯* states are expected to be found in future runs of the LHC or in photoproduction experiments.


MIAPbP
(357)Probing flavor nonuniversal theories through Higgs physics at the LHC and future colliders
  • Wen Han Chiu,
  • Zhen Liu,
  • Lian-Tao Wang
Physical Review D (02/2020) doi:10.1103/PhysRevD.101.035045
abstract + abstract -

We explored the possibility that Higgs coupling to new physics violates flavor universality. In particular, we parametrize such models with dimension-six effective operators which modify the coupling between the first generation quarks, Higgs boson, and Z boson. Through the use of boosted Higgsstrahlung events at both the HL-LHC and potential future hadron colliders, as well as existing ATLAS data for background estimates, we projected constraints on the scale of new physics as a function of the Wilson coefficient. The high energy Z h process will provide unique information about these class of operators, and the sensitivity is competitive with the LEP electroweak precision measurements. We include different scenarios of the overall systematic uncertainties and the PDF uncertainties when presenting the projected sensitivities. We also discuss the constraints from flavor changing neutral currents to these flavor-violating models and the complementarity of the exotic Higgs decay to the Z h process.


MIAPbP
(356)Multiphonon excitations from dark matter scattering in crystals
  • Brian Campbell-Deem,
  • Peter Cox,
  • Simon Knapen,
  • Tongyan Lin,
  • Tom Melia
Physical Review D (02/2020) doi:10.1103/PhysRevD.101.036006
abstract + abstract -

For direct detection of sub-MeV dark matter, a promising strategy is to search for individual phonon excitations in a crystal. We perform an analytic calculation of the rate for light dark matter (keV <mDM<MeV ) to produce two acoustic phonons through scattering in cubic crystals such as GaAs, Ge, Si, and diamond. The multiphonon rate is always smaller than the rate to produce a single optical phonon, whenever the latter is kinematically accessible. In Si and diamond, there is a dark matter mass range for which multiphonon production can be the most promising process, depending on the experimental threshold.


MIAPbP
(355)A holographic perspective on the axion quality problem
  • Peter Cox,
  • Tony Gherghetta,
  • Minh D. Nguyen
Journal of High Energy Physics (01/2020) doi:10.1007/JHEP01(2020)188
abstract + abstract -

The axion provides a compelling solution to the strong CP problem as well as a candidate for the dark matter of the universe. However, the axion solution relies on the spontaneous breaking of a global U(1)PQ symmetry, which is also explicitly violated by quantum gravity. To preserve the axion solution, gravitational violations of the U(1)PQ symmetry must be suppressed to sufficiently high order. We present a simple, geometric solution of the axion quality problem by modelling the axion with a bulk complex scalar field in a slice of AdS5, where the U(1)PQ symmetry is spontaneously broken in the bulk but explicitly broken on the UV brane. By localising the axion field towards the IR brane, gravitational violations of the PQ symmetry on the UV brane are sufficiently sequestered. This geometric solution is holographically dual to 4D strong dynamics where the global U(1)PQ is an accidental symmetry to sufficiently high order.


MIAPbP
(354)Chiral Froggatt-Nielsen models, gauge anomalies and flavourful axions
  • Q. Bonnefoy,
  • E. Dudas,
  • S. Pokorski
Journal of High Energy Physics (01/2020) doi:10.1007/JHEP01(2020)191
abstract + abstract -

We study UV-complete Froggatt-Nielsen-like models for the generation of mass and mixing hierarchies, assuming that the integrated heavy fields are chiral with respect to an abelian Froggatt-Nielsen symmetry. It modifies the mixed anomalies with respect to the Standard Model gauge group, which opens up the possibility to gauge the Froggatt-Nielsen symmetry without the need to introduce additional spectator fermions, while keeping mass matrices usually associated to anomalous flavour symmetries. We give specific examples where this happens, and we study the flavourful axion which arises from an accidental Peccei-Quinn symmetry in some of those models. Such an axion is typically more coupled to matter than in models with spectator fermions.


MIAPbP
(353)Dark Matter benchmark models for early LHC Run-2 Searches: Report of the ATLAS/CMS Dark Matter Forum
  • Daniel Abercrombie,
  • Nural Akchurin,
  • Ece Akilli,
  • Juan Alcaraz Maestre,
  • Brandon Allen
  • +135
  • Barbara Alvarez Gonzalez,
  • Jeremy Andrea,
  • Alexandre Arbey,
  • Georges Azuelos,
  • Patrizia Azzi,
  • Mihailo Backović,
  • Yang Bai,
  • Swagato Banerjee,
  • James Beacham,
  • Alexander Belyaev,
  • Antonio Boveia,
  • Amelia Jean Brennan,
  • Oliver Buchmueller,
  • Matthew R. Buckley,
  • Giorgio Busoni,
  • Michael Buttignol,
  • Giacomo Cacciapaglia,
  • Regina Caputo,
  • Linda Carpenter,
  • Nuno Filipe Castro,
  • Guillelmo Gomez Ceballos,
  • Yangyang Cheng,
  • John Paul Chou,
  • Arely Cortes Gonzalez,
  • Chris Cowden,
  • Francesco D'Eramo,
  • Annapaola De Cosa,
  • Michele De Gruttola,
  • Albert De Roeck,
  • Andrea De Simone,
  • Aldo Deandrea,
  • Zeynep Demiragli,
  • Anthony DiFranzo,
  • Caterina Doglioni,
  • Tristan du Pree,
  • Robin Erbacher,
  • Johannes Erdmann,
  • Cora Fischer,
  • Henning Flaecher,
  • Patrick J. Fox,
  • Benjamin Fuks,
  • Marie-Helene Genest,
  • Bhawna Gomber,
  • Andreas Goudelis,
  • Johanna Gramling,
  • John Gunion,
  • Kristian Hahn,
  • Ulrich Haisch,
  • Roni Harnik,
  • Philip C. Harris,
  • Kerstin Hoepfner,
  • Siew Yan Hoh,
  • Dylan George Hsu,
  • Shih-Chieh Hsu,
  • Yutaro Iiyama,
  • Valerio Ippolito,
  • Thomas Jacques,
  • Xiangyang Ju,
  • Felix Kahlhoefer,
  • Alexis Kalogeropoulos,
  • Laser Seymour Kaplan,
  • Lashkar Kashif,
  • Valentin V. Khoze,
  • Raman Khurana,
  • Khristian Kotov,
  • Dmytro Kovalskyi,
  • Suchita Kulkarni,
  • Shuichi Kunori,
  • Viktor Kutzner,
  • Hyun Min Lee,
  • Sung-Won Lee,
  • Seng Pei Liew,
  • Tongyan Lin,
  • Steven Lowette,
  • Romain Madar,
  • Sarah Malik,
  • Fabio Maltoni,
  • Mario Martinez Perez,
  • Olivier Mattelaer,
  • Kentarou Mawatari,
  • Christopher McCabe,
  • Théo Megy,
  • Enrico Morgante,
  • Stephen Mrenna,
  • Chang-Seong Moon,
  • Siddharth M. Narayanan,
  • Andy Nelson,
  • Sérgio F. Novaes,
  • Klaas Ole Padeken,
  • Priscilla Pani,
  • Michele Papucci,
  • Manfred Paulini,
  • Christoph Paus,
  • Jacopo Pazzini,
  • Björn Penning,
  • Michael E. Peskin,
  • Deborah Pinna,
  • Massimiliano Procura,
  • Shamona F. Qazi,
  • Davide Racco,
  • Emanuele Re,
  • Antonio Riotto,
  • Thomas G. Rizzo,
  • Rainer Roehrig,
  • David Salek,
  • Arturo Sanchez Pineda,
  • Subir Sarkar,
  • Alexander Schmidt,
  • Steven Randolph Schramm,
  • William Shepherd,
  • Gurpreet Singh,
  • Livia Soffi,
  • Norraphat Srimanobhas,
  • Kevin Sung,
  • Tim M. P. Tait,
  • Timothee Theveneaux-Pelzer,
  • Marc Thomas,
  • Mia Tosi,
  • Daniele Trocino,
  • Sonaina Undleeb,
  • Alessandro Vichi,
  • Fuquan Wang,
  • Lian-Tao Wang,
  • Ren-Jie Wang,
  • Nikola Whallon,
  • Steven Worm,
  • Mengqing Wu,
  • Sau Lan Wu,
  • Hongtao Yang,
  • Yong Yang,
  • Shin-Shan Yu,
  • Bryan Zaldivar,
  • Marco Zanetti,
  • Zhiqing Zhang,
  • Alberto Zucchetta
  • (less)
Physics of the Dark Universe (01/2020) doi:10.1016/j.dark.2019.100371
abstract + abstract -

This document is the final report of the ATLAS-CMS Dark Matter Forum, a forum organized by the ATLAS and CMS collaborations with the participation of experts on theories of Dark Matter, to select a minimal basis set of dark matter simplified models that should support the design of the early LHC Run-2 searches. A prioritized, compact set of benchmark models is proposed, accompanied by studies of the parameter space of these models and a repository of generator implementations. This report also addresses how to apply the Effective Field Theory formalism for collider searches and present the results of such interpretations.


MIAPbP
(352)OGLE-ing the Magellanic System: Cepheids in the Bridge
  • Anna M. Jacyszyn-Dobrzeniecka,
  • Igor Soszyński,
  • Andrzej Udalski,
  • Michał K. Szymański,
  • Dorota M. Skowron
  • +10
  • Jan Skowron,
  • Przemek Mróz,
  • Katarzyna Kruszyńska,
  • Patryk Iwanek,
  • Paweł Pietrukowicz,
  • Radosław Poleski,
  • Szymon Kozłowski,
  • Krzysztof Ulaczyk,
  • Krzysztof Rybicki,
  • Marcin Wrona
  • (less)
The Astrophysical Journal (01/2020) doi:10.3847/1538-4357/ab61f1
abstract + abstract -

We present a detailed analysis of the Magellanic Bridge Cepheid sample constructed using the Optical Gravitational Lensing Experiment Collection of Variable Stars. Our updated Bridge sample contains 10 classical and 13 anomalous Cepheids. We calculate their individual distances using optical period-Wesenheit relations and construct three-dimensional maps. Classical Cepheid (CC) on-sky locations match very well neutral hydrogen and young stars distributions; thus, they add to the overall young Bridge population. In three dimensions, 8 out of 10 CCs form a bridge-like connection between the Magellanic Clouds. The other two are located slightly farther away and may constitute the Counter Bridge. We estimate ages of our Cepheids to be less than 300 Myr for from 5 up to 8 out of 10, depending on whether the rotation is included. This is in agreement with a scenario where these stars were formed in situ after the last encounter of the Magellanic Clouds. Cepheids' proper motions reveal that they are moving away from both Large and Small Magellanic Clouds. Anomalous Cepheids are more spread than CCs in both two and three dimensions, even though they form a rather smooth connection between the Magellanic Clouds. However, this connection does not seem to be bridge-like, as there are many outliers around both Magellanic Clouds.


MIAPbP
(351)OGLE-ing the Magellanic System: RR Lyrae Stars in the Bridge
  • Anna M. Jacyszyn-Dobrzeniecka,
  • Przemek Mróz,
  • Katarzyna Kruszyńska,
  • Igor Soszyński,
  • Dorota M. Skowron
  • +10
  • Andrzej Udalski,
  • Michał K. Szymański,
  • Patryk Iwanek,
  • Jan Skowron,
  • Paweł Pietrukowicz,
  • Radosław Poleski,
  • Szymon Kozłowski,
  • Krzysztof Ulaczyk,
  • Krzysztof Rybicki,
  • Marcin Wrona
  • (less)
The Astrophysical Journal (01/2020) doi:10.3847/1538-4357/ab61f2
abstract + abstract -

We use the extended and updated Optical Gravitational Lensing Experiment (OGLE) Collection of Variable Stars to thoroughly analyze the distribution of RR Lyrae stars in the Magellanic Bridge. We use photometric metallicities to derive the absolute Wesenheit magnitude and individual distance of each RR Lyrae star. We confirm results from our earlier study showing that RR Lyrae stars are present in between the Magellanic Clouds, though their three-dimensional distribution more resembles two extended overlapping structures than a strict bridge-like connection. The contours do connect in the southern parts of the Bridge, albeit on a level too low to state that an evident connection exists. To test the sample numerically, we use multi-Gaussian fitting and conclude that there is no additional population or overdensity located in the Bridge. We also try to reproduce results on the putative RR Lyrae Magellanic Bridge stream by selecting RR Lyrae candidates from Gaia Data Release 1. We show that we are not able to obtain the evident connection of the Clouds without many spurious sources in the sample, as the cuts are not able to remove artifacts without eliminating the evident connection at the same time. Moreover, for the first time, we present the Gaia Data Release 2 RR Lyrae stars in the Magellanic Bridge area and show that their distribution matches our results.


MIAPbP
(350)Minimal signatures of the standard model in non-Gaussianities
  • Anson Hook,
  • Junwu Huang,
  • Davide Racco
Physical Review D (01/2020) doi:10.1103/PhysRevD.101.023519
abstract + abstract -

We show that the leading coupling between a shift symmetric inflaton and the standard model fermions leads to an induced electroweak symmetry breaking due to particle production during inflation, and as a result, a unique oscillating feature in non-Gaussianities. In this one parameter model, the enhanced production of standard model fermions dynamically generates a new electroweak symmetry breaking minimum, where the Higgs field classically rolls to. The production of fermions stops when the Higgs expectation value and hence the fermion masses become too large, suppressing fermion production. The balance between the above-mentioned effects gives the standard model fermions masses that are uniquely determined by their couplings to the inflaton. In particular, the heaviest standard model fermion, the top quark, can produce a distinct cosmological collider physics signature characterized by a one-to-one relation between amplitude and frequency of the oscillating signal, which is observable at future 21-cm surveys.


MIAPbP
(349)Gauging the accidental symmetries of the standard model, and implications for the flavor anomalies
  • Wolfgang Altmannshofer,
  • Joe Davighi,
  • Marco Nardecchia
Physical Review D (01/2020) doi:10.1103/PhysRevD.101.015004
abstract + abstract -

We explore the possibility that lepton family numbers and baryon number are such good symmetries of Nature because they are the global remnant of a spontaneously broken gauge symmetry. An almost arbitrary linear combination of these symmetries (together with a component of global hypercharge) can be consistently gauged, if the Standard Model (SM) fermion content is augmented by three chiral SM singlet states. Within this framework of U (1 ) extensions of the SM one generically expects flavor nonuniversality to emerge in the charged leptons, in such a way that naturally prevents lepton flavor violation, by aligning the mass and weak eigenbases. For quarks, all the SM Yukawa couplings responsible for their observed masses and mixings arise at the renormalizable level. We perform fits to show that models in this class can explain RK(*) and the other neutral current B anomaly data if we introduce a heavy vectorlike quark to mediate the required quark flavor violation, while simultaneously satisfying other constraints from direct Z' searches at the LHC, Bs meson mixing, a number of electroweak precision observables, and neutrino trident production. Within this symmetry-motivated framework of models, we find interesting implications for the flavor anomalies; notably, any axial couplings of the Z' to electrons and muons must be flavor universal, with the flavor universality violation arising solely from the vectorlike couplings. We also comment on the generation of neutrino masses in these models.


MIAPbP
(348)The impact of planet wakes on the location and shape of the water ice line in a protoplanetary disk
  • Alexandros Ziampras,
  • Sareh Ataiee,
  • Wilhelm Kley,
  • Cornelis P. Dullemond,
  • Clément Baruteau
Astronomy and Astrophysics (01/2020) doi:10.1051/0004-6361/201936495
abstract + abstract -

Context. Planets in accretion disks can excite spiral shocks and if these planets are massive enough, they can even open gaps in their vicinity. Both of these effects can influence the overall thermal structure of the disk.
Aims: We model planets of different masses and semimajor axes in disks of various viscosities and accretion rates to examine their impact on disk thermodynamics and to highlight the mutable, non-axisymmetric nature of ice lines in systems with massive planets.
Methods: We conducted a parameter study using numerical hydrodynamics simulations where we treated viscous heating, thermal cooling, and stellar irradiation as additional source terms in the energy equation, with some runs including radiative diffusion. Our parameter space consists of a grid containing different combinations of planet and disk parameters.
Results: Both gap opening and shock heating can displace the ice line, with the effects amplified for massive planets in optically thick disks. The gap region can split an initially hot (T > 170 K) disk into a hot inner disk and a hot ring just outside of the planet's location, while shock heating can reshape the originally axisymmetric ice line into water-poor islands along spirals. We also find that radiative diffusion does not alter the picture significantly in this context.
Conclusions: Shock heating and gap opening by a planet can effectively heat up optically thick disks and, in general, they can move or reshape the water ice line. This can affect the gap structure and migration torques. It can also produce azimuthal features that follow the trajectory of spiral arms, creating hot zones which lead to "islands" of vapor and ice around spirals that could affect the accretion or growth of icy aggregates.


MIAPbP
(347)From boundary data to bound states
  • Gregor Kälin,
  • Rafael A. Porto
Journal of High Energy Physics (01/2020) doi:10.1007/JHEP01(2020)072
abstract + abstract -

We introduce a — somewhat holographic — dictionary between gravitational observables for scattering processes (measured at the boundary) and adiabatic invariants for bound orbits (in the bulk), to all orders in the Post-Minkowskian (PM) expansion. Our map relies on remarkable connections between the relative momentum of the twobody problem, the classical limit of the scattering amplitude and the deflection angle in hyperbolic motion. These relationships allow us to compute observables for generic orbits (such as the periastron advance ∆Φ) through analytic continuation, via a radial action depending only on boundary data. A simplified (more geometrical) map can be obtained for circular orbits, enabling us to extract the orbital frequency as a function of the (conserved) binding energy, Ω(E), directly from scattering information. As an example, using the results in Bernet al. [36, 37], we readily derive Ω(E) and ∆Φ(J, E) to two-loop orders. We also provide closed-form expressions for the orbital frequency and periastron advance at tree-level and one-loop order, respectively, which capture a series of exact terms in the Post-Newtonian expansion. We then perform a partial PM resummation, using a no-recoil approximation for the amplitude. This limit is behind the map between the scattering angle for a test-particle and the two-body dynamics to 2PM. We show that it also captures a subset of higher order terms beyond the test-particle limit. While a (rather lengthy) Hamiltonian may be derived as an intermediate step, our map applies directly between gauge invariant quantities. Our findings provide a starting point for an alternative approach to the binary problem. We conclude with future directions and some speculations on the classical double copy.


MIAPbP
(346)Di-Higgs boson peaks and top valleys: Interference effects in Higgs sector extensions
  • Philipp Basler,
  • Sally Dawson,
  • Christoph Englert,
  • Margarete Mühlleitner
Physical Review D (01/2020) doi:10.1103/PhysRevD.101.015019
abstract + abstract -

In models with extended scalars and C P violation, resonance searches in double Higgs final states stand in competition with related searches in top quark final states as optimal channels for the discovery of beyond the Standard Model (BSM) physics. This complementarity is particularly relevant for benchmark scenarios that aim to highlight multi-Higgs production as a standard candle for the study of BSM phenomena. In this paper, we compare interference effects in t t ¯ final states with correlated phenomena in double Higgs production in the complex singlet and the complex two-Higgs-doublet models. Our results indicate that the BSM discovery potential in di-Higgs searches can be underestimated in comparison to t t ¯ resonance searches. Top pair final states are typically suppressed due to destructive signal-background interference, while h h final states can be enhanced due to signal-signal interference. For parameter choices where the two heavy Higgs resonances are well separated in mass, top final states are suppressed relative to the naive signal expectation, while estimates of the production cross section times branching ratio remain accurate at the O (10 %) level for double Higgs final states.


MIAPbP
(345)Mass agnostic jet taggers
  • Layne Bradshaw,
  • Rashmish K. Mishra,
  • Andrea Mitridate,
  • Bryan Ostdiek
SciPost Physics (01/2020) doi:10.21468/SciPostPhys.8.1.011
abstract + abstract -

Searching for new physics in large data sets needs a balance between two competing effects---signal identification vs background distortion. In this work, we perform a systematic study of both single variable and multivariate jet tagging methods that aim for this balance. The methods preserve the shape of the background distribution by either augmenting the training procedure or the data itself. Multiple quantitative metrics to compare the methods are considered, for tagging 2-, 3-, or 4-prong jets from the QCD background. This is the first study to show that the data augmentation techniques of Planing and PCA based scaling deliver similar performance as the augmented training techniques of Adversarial NN and uBoost, but are both easier to implement and computationally cheaper.


MIAPbP
(344)Searches for other vacua. Part II. A new Higgstory at the cosmological collider
  • Anson Hook,
  • Junwu Huang,
  • Davide Racco
Journal of High Energy Physics (01/2020) doi:10.1007/JHEP01(2020)105
abstract + abstract -

The detection of an oscillating pattern in the bispectrum of density perturbations could suggest the existence of a high-energy second minimum in the Higgs potential. If the Higgs field resided in this new minimum during inflation and was brought back to the electroweak vacuum by thermal corrections during reheating, the coupling of Standard Model particles to the inflaton would leave its imprint on the bispectrum. We focus on the fermions, whose dispersion relation can be modified by the coupling to the inflaton, leading to an enhanced particle production during inflation even if their mass during inflation is larger than the Hubble scale. This results in a large non-analytic contribution to non-Gaussianities, with an amplitude fNL as large as 100 in the squeezed limit, potentially detectable in future 21-cm surveys. Measuring the contributions from two fermions would allow us to compute the ratio of their masses, and to ascribe the origin of the signal to a new Higgs minimum. Such a discovery would be a tremendous step towards understanding the vacuum instability of the Higgs potential, and could have fascinating implications for anthropic considerations.


RU-D
(343)Long-lived Dust Rings around HD 169142
  • Claudia Toci,
  • Giuseppe Lodato,
  • Davide Fedele,
  • Leonardo Testi,
  • Christophe Pinte
The Astrophysical Journal (01/2020) doi:10.3847/2041-8213/ab5c87
abstract + abstract -

Recent Atacama Large Millimeter/submillimeter Array (ALMA) observations of the protoplanetary disk around HD 169142 reveal a peculiar structure made of concentric dusty rings: a main ring at ∼20 au, a triple system of rings at ∼55-75 au in millimetric continuum emission, and a perturbed gas surface density from the 12CO,13CO, and C18O (J = 2-1) surface brightness profile. In this Letter, we perform 3D numerical simulations and radiative transfer modeling exploring the possibility that two giant planets interacting with the disk and orbiting in resonant locking can be responsible for the origin of the observed dust inner rings structure. We find that in this configuration the dust structure is actually long lived while the gas mass of the disk is accreted onto the star and the giant planets, emptying the inner region. In addition, we also find that the innermost planet is located at the inner edge of the dust ring, and can accrete mass from the disk, generating a signature in the dust ring shape that can be observed in mm ALMA observations.


CN-2
RU-D
(342)Demographics of disks around young very low-mass stars and brown dwarfs in Lupus
  • E. Sanchis,
  • L. Testi,
  • A. Natta,
  • C. F. Manara,
  • B. Ercolano
  • +13
  • T. Preibisch,
  • T. Henning,
  • S. Facchini,
  • A. Miotello,
  • I. de Gregorio-Monsalvo,
  • C. Lopez,
  • K. Mužić,
  • I. Pascucci,
  • A. Santamaría-Miranda,
  • A. Scholz,
  • M. Tazzari,
  • S. van Terwisga,
  • J. P. Williams
  • (less)
Astronomy and Astrophysics (01/2020) doi:10.1051/0004-6361/201936913
abstract + abstract -

We present new 890 μm continuum ALMA observations of five brown dwarfs (BDs) with infrared excess in Lupus I and III, which in combination with four previously observed BDs allowed us to study the millimeter properties of the full known BD disk population of one star-forming region. Emission is detected in five out of the nine BD disks. Dust disk mass, brightness profiles, and characteristic sizes of the BD population are inferred from continuum flux and modeling of the observations. Only one source is marginally resolved, allowing for the determination of its disk characteristic size. We conduct a demographic comparison between the properties of disks around BDs and stars in Lupus. Due to the small sample size, we cannot confirm or disprove a drop in the disk mass over stellar mass ratio for BDs, as suggested for Ophiuchus. Nevertheless, we find that all detected BD disks have an estimated dust mass between 0.2 and 3.2 M; these results suggest that the measured solid masses in BD disks cannot explain the observed exoplanet population, analogous to earlier findings on disks around more massive stars. Combined with the low estimated accretion rates, and assuming that the mm-continuum emission is a reliable proxy for the total disk mass, we derive ratios of Ṁacc/Mdisk that are significantly lower than in disks around more massive stars. If confirmed with more accurate measurements of disk gas masses, this result could imply a qualitatively different relationship between disk masses and inward gas transport in BD disks.


RU-A
(341)On the importance of NNLO QCD and isospin-breaking corrections in ε′/ ε
  • Jason Aebischer,
  • Christoph Bobeth,
  • Andrzej J. Buras
European Physical Journal C (01/2020) e-Print:1909.05610 doi:10.1140/epjc/s10052-019-7549-y
abstract + abstract -

Following the 1999 analysis of Gambino, Haisch and one of us, we stress that all the recent NLO analyses of ε′/ ε in the Standard Model (SM) suffer from the renormalization scheme dependence present in the electroweak penguin contributions as well as from scale uncertainties in them related to the matching scale μW and in particular to μt in mt(μt). We also reemphasize the important role of isospin-breaking and QED effects in the evaluation of ε′/ ε. Omitting all these effects, as done in the 2015 analysis by RBC-UKQCD collaboration, and choosing as an example the QCD penguin (Q6) and electroweak penguin (Q8) parameters B6(1/2) and B8(3/2) to be B6(1/2)=0.80±0.08 and B8(3/2)=0.76±0.04 at μ=mc=1.3GeV, we find (ε′/ε)SM=(9.4±3.5)×10-4, whereas including them results in (ε′/ε)SM=(5.6±2.4)×10-4. This is an example of an anomaly at the 3.3σ level, which would be missed without these corrections. NNLO QCD contributions to QCD penguins are expected to further enhance this anomaly. We provide a table for ε′/ ε for different values of B6(1/2) and the isospin-breaking parameter Ω ^ eff, that should facilitate monitoring the values of ε′/ ε in the SM when the RBC-UKQCD calculations of hadronic matrix elements including isospin-breaking corrections and QED effects will improve with time.