Thu·Feb 25, 2021Thursday·February 25, 2021

1. 01*

   {\Lambda} polarization from thermalized jet energy

   Willian Matioli Serenone🇧🇷 · João Guilherme Prado Barbon🇧🇷 · David Dobrigkeit Chinellato🇧🇷 · Michael Annan Lisa🇺🇸 · Chun Shen🇺🇸 · Jun Takahashi🇧🇷 · Giorgio Torrieri🇧🇷

   We examine the formation of vortical "smoke rings" as a result of thermalization of energy lost by a jet. We simulate the formation and evolution of these rings using hydrodynamics and define an observable that allows to probe this phenomenon experimentally. We argue that observation of vorticity associated with jets would be an experimental confirmation of the thermalization of the energy lost by quenched jets, and also a probe of shear viscosity.

   hep-phPLB(2021)·35 citations
2. 02*

   Resolving the LMA-dark NSI degeneracy with coherent neutrino-nucleus scattering

   Mariano Esteves Chaves🇧🇷 · Thomas Schwetz🇩🇪

   In the presence of non-standard neutrino interactions (NSI), a degeneracy exists in neutrino oscillation data, which involves the flipping of the octant of the mixing angle ${\theta }_{12}$ and the type of the neutrino mass ordering. In this article, we revisit the status of this degeneracy in the light of recent data on coherent elastic neutrino-nucleus scattering (CE$\nu$NS) from the COHERENT experiment. For general relative couplings to up and down quarks, the degeneracy is disfavoured at the $2\sigma$ level by the latest data but remains at a higher confidence level. We investigate the requirements of future CE$\nu$NS measurements to resolve the degeneracy with high significance. We find that a measurement involving both, electron and muon neutrino flavours and a target with a neutron-to-proton ratio close to 1 is required. For example, an experiment with a silicon target at the European Spallation Source can resolve the degeneracy at more than $4\sigma$ for arbitrary relative couplings to up and down quarks.

   hep-phhep-exnucl-exJHEP(2021)·22 citations
3. 03*

   Integrating out heavy fields in the path integral using the background-field method: general formalism

   Stefan Dittmaier🇩🇪 · Sebastian Schuhmacher🇩🇪 · Maximilian Stahlhofen🇩🇪

   Building on an older method used to derive non-decoupling effects of a heavy Higgs boson in the Standard Model, we describe a general procedure to integrate out heavy fields in the path integral. The derivation of the corresponding effective Lagrangian including the one-loop contributions of the heavy particle(s) is particularly transparent, flexible, and algorithmic. The background-field formalism allows for a clear separation of tree-level and one-loop effects involving the heavy fields. Using expansion by regions the one-loop effects are further split into contributions from large and small momentum modes. The former are contained in Wilson coefficients of effective operators, the latter are reproduced by one-loop diagrams involving effective tree-level couplings. The method is illustrated by calculating potential non-decoupling effects of a heavy Higgs boson in a singlet Higgs extension of the Standard Model. In particular, we work in a field basis corresponding to mass eigenstates and properly take into account non-vanishing mixing between the two Higgs fields of the model. We also show that a proper choice of renormalization scheme for the non-standard sector of the underlying full theory is crucial for the construction of a consistent effective field theory.

   hep-phhep-thEPJC(2021)·58 citations
4. 04*

   Feebly-Interacting Particles:FIPs 2020 Workshop Report

   Prateek Agrawal🇬🇧 · Martin Bauer🇬🇧 · James Beacham🇺🇸 · Asher Berlin🇺🇸 · Alexey Boyarsky🇳🇱 · Susana Cebrian🇪🇸 · Xabier Cid-Vidal🇪🇸 · David d'Enterria🇨🇭 · Albert De Roeck🇨🇭 · Marco Drewes🇧🇪 · Bertrand Echenard🇺🇸 · Maurizio Giannotti🇺🇸 and 34 other authors

   With the establishment and maturation of the experimental programs searching for new physics with sizeable couplings at the LHC, there is an increasing interest in the broader particle and astrophysics community for exploring the physics of light and feebly-interacting particles as a paradigm complementary to a New Physics sector at the TeV scale and beyond. FIPs 2020 has been the first workshop fully dedicated to the physics of feebly-interacting particles and was held virtually from 31 August to 4 September 2020. The workshop has gathered together experts from collider, beam dump, fixed target experiments, as well as from astrophysics, axions/ALPs searches, current/future neutrino experiments, and dark matter direct detection communities to discuss progress in experimental searches and underlying theory models for FIPs physics, and to enhance the cross-fertilisation across different fields. FIPs 2020 has been complemented by the topical workshop "Physics Beyond Colliders meets theory", held at CERN from 7 June to 9 June 2020. This document presents the summary of the talks presented at the workshops and the outcome of the subsequent discussions held immediately after. It aims to provide a clear picture of this blooming field and proposes a few recommendations for the next round of experimental results.

   hep-phEPJC(2021)·388 citations
5. 05*

   The QED Initial State Corrections to the Forward-Backward Asymmetry of $e^{+}{e}^{-}\to {\gamma }^{\ast }/Z^{0\ast }$ to Higher Orders

   J. Blümlein🇩🇪 · A. De Freitas🇩🇪 · K. Schönwald🇩🇪

   The QED initial state corrections are calculated to the forward-backward asymmetry for $e^{+}{e}^{-}\to {\gamma }^{\ast }/{Z^0}^{\ast }$ in the leading logarithmic approximation to $O({\alpha }^6{L}^6)$ extending the known corrections up to $O({\alpha }^2{L}^2)$ in analytic form. We use the method of massive on-shell operator matrix elements and present the radiators both in Mellin-$N$ and momentum fraction $z$-space. Numerical results are presented for various energies around the $Z$-peak by also including energy cuts. These corrections are of relevance for the precision measurements at the FCC$\_$ee.

   hep-phhep-exPLB(2021)·14 citations
6. 06*

   Study of form factors and branching ratios for $D\to S,Al\overline{{\nu }_l}$ with light-cone sum rules

   Qi Huang🇨🇳 · Yan-Jun Sun🇨🇳 · Di Gao🇨🇳 · Guo-Hua Zhao🇨🇳 · Bin Wang🇨🇳 · Wei Hong🇨🇳

   We systematically study the semileptonic decay process of $D\to S,Al\overline{{\nu }_l}(l=e,\mu )$ by light-cone sum rules (LCSR) with chiral currents, calculate the form factors containing only the contribution of the leading twist light-cone distribution amplitudes (LCDAs). For scalar mesons $a_0(980)$ and $a_0(1450)$, we take them as $q\bar{q}$ states. For axial-vector meson, we study $a_1(1260)(1^3{p}^1)$ and $b_1(1235)(1^1{p}^1)$. Based on the results of these form factors, we further present the branching ratios of these semileptonic decay processes. The numerical results for $D\to a_0(980),b_1(1235)l\overline{{\nu }_l}$ are in good agreement with experiments and that for $D\to a_0(1450)l\overline{{\nu }_l}$ process are expected to be tested experimentally in the future.

   hep-ph17 citations
7. 07*

   Probing neutrino magnetic moment at the Jinping neutrino experiment

   Baobiao Yue🇨🇳 · Jiajun Liao🇨🇳 · Jiajie Ling🇨🇳

   Neutrino magnetic moment ($\nu$MM) is an important property of massive neutrinos. The recent anomalous excess at few keV electronic recoils observed by the Xenon1T collaboration might indicate a $\sim 2.2\times 10^{-11}{\mu }_B$ effective neutrino magnetic moment (${\mu }_{\nu }^{eff}$) from solar neutrinos. Therefore, it is essential to carry out the $\nu$MM searches at a different experiment to confirm or exclude such hypothesis. We study the feasibility of doing $\nu$MM measurement with 4 kton active mass at Jinping neutrino experiment using electron recoil data from both natural and artificial neutrino sources. The sensitivity of ${\mu }_{\nu }^{eff}$ can reach $1.2\times 10^{-11}{\mu }_B$ at 90\% C.L. with 10-year data taking of solar neutrinos. Besides the intrinsic low energy background ${}^{14}$C in the liquid scintillator, we find the sensitivity to $\nu$MM is highly correlated with the systematic uncertainties of $pp$ and ${}^{85}$Kr. Reducing systematic uncertainties ($pp$ and ${}^{85}$Kr) and the intrinsic background (${}^{14}$C and ${}^{85}$Kr) can help to improve sensitivities below these levels and reach the region of astrophysical interest. With a 3 mega-Curie (MCi) artificial neutrino source ${}^{51}$Cr installed at Jinping neutrino detector for 55 days, it could give us a sensitivity to the electron neutrino magnetic moment (${\mu }_{{\nu }_e}$) with $1.1\times 10^{-11}{\mu }_B$ at 90\% C.L.. With the combination of those two measurements, the flavor structure of the neutrino magnetic moment can be also probed at Jinping.

   hep-phhep-exJHEP(2021)·7 citations
8. 08*

   A novel observable for $CP$ violation in multi-body decays and its application potential to charm and beauty meson decays

   Zhen-Hua Zhang🇨🇳

   A novel observable measuring the $CP$ asymmetry in multi-body decays of heavy mesons, which is called the forward-backward asymmetry induced $CP$ asymmetry (FBI-$CP$A), $A_{CP}^{FB}$, is introduced. This observable has the dual advantages that 1) it can isolate the $CP$ asymmetry associated with the interference of the $S$- and $P$-wave amplitude from that associated with the $S$- or $P$-wave amplitude alone; 2) it can effectively almost double the statistics comparing to the conventionally defined regional $CP$ asymmetry. We also suggest to perform the measurements of FBI-$CP$A in some three-body decay channels of charm and beauty mesons.

   hep-phhep-exPLB(2021)·14 citations
9. 09*

   Solar reflection of light dark matter with heavy mediators

   Timon Emken🇸🇪

   The direct detection of sub-GeV dark matter particles is hampered by their low energy deposits. If the maximum deposit allowed by kinematics falls below the energy threshold of a direct detection experiment, it is unable to detect these light particles. Mechanisms that boost particles from the galactic halo can therefore extend the sensitivity of terrestrial direct dark matter searches to lower masses. Sub-GeV and sub-MeV dark matter particles can be efficiently accelerated by colliding with thermal nuclei and electrons of the solar plasma respectively. This process is called 'solar reflection'. In this paper, we present a comprehensive study of solar reflection via electron and/or nuclear scatterings using Monte Carlo simulations of dark matter trajectories through the Sun. We study the properties of the boosted dark matter particles, obtain exclusion limits based on various experiments probing both electron and nuclear recoils, and derive projections for future detectors. In addition, we find and quantify a novel, distinct annual modulation signature of a potential solar reflection signal which critically depends on the anisotropies of the boosted dark matter flux ejected from the Sun. Along with this paper, we also publish the corresponding research software.

   hep-phastro-ph.COPRD(2022)·69 citations
10. 10*

    Baryogenesis and gravity waves from a UV-completed electroweak phase transition

    James M. Cline🇨🇦 · Avi Friedlander🇨🇦 · Dong-Ming He🇨🇳 · Kimmo Kainulainen🇫🇮 · Benoit Laurent🇨🇦 · David Tucker-Smith🇺🇸

    We study gravity wave production and baryogenesis at the electroweak phase transition, in a real singlet scalar extension of the Standard Model, including vector-like top partners to generate the CP violation needed for electroweak baryogenesis (EWBG). The singlet makes the phase transition strongly first-order through its coupling to the Higgs boson, and it spontaneously breaks CP invariance through a dimension-5 contribution to the top quark mass term, generated by integrating out the heavy top quark partners. We improve on previous studies by incorporating updated transport equations, compatible with large bubble wall velocities. The wall speed and thickness are computed directly from the microphysical parameters rather than treating them as free parameters, allowing for a first-principles computation of the baryon asymmetry. The size of the CP-violating dimension-5 operator needed for EWBG is constrained by collider, electroweak precision, and renormalization group running constraints. We identify regions of parameter space that can produce the observed baryon asymmetry or observable gravitational (GW) wave signals. Contrary to standard lore, we find that for strong deflagrations, the efficiencies of large baryon asymmetry production and strong GW signals can be positively correlated. However we find the overall likelihood of observably large GW signals to be smaller than estimated in previous studies. In particular, only detonation-type transitions are predicted to produce observably large gravitational waves.

    hep-phastro-ph.COPRD(2021)·122 citations
11. 11*

    Preheating from target space curvature and unitarity violation: Analysis in field space

    Yohei Ema🇩🇪 · Ryusuke Jinno🇩🇪 · Kazunori Nakayama🇯🇵 · Jorinde van de Vis🇩🇪

    We study particle production and unitarity violation caused by a curved target space right after inflation. We use the inflaton field value instead of cosmic time as the time variable, and derive a semiclassical formula for the spectrum of produced particles. We then derive a simple condition for unitarity violation during preheating, which we confirm by our semiclassical method and numerical solution. This condition depends not only on the target space curvature but also on the height of the inflaton potential at the end of inflation. This condition tells us, for instance, that unitarity is violated in running kinetic inflation and Higgs inflation, while unitarity is conserved in $\alpha$-attractor inflation and Higgs-Palatini inflation.

    hep-phastro-ph.COPRD(2021)·24 citations
12. 12*

    Axions: From Magnetars and Neutron Star Mergers to Beam Dumps and BECs

    Jean-François Fortin🇨🇦 · Huai-Ke Guo🇺🇸 · Steven P. Harris🇺🇸 · Doojin Kim🇺🇸 · Kuver Sinha🇺🇸 · Chen Sun🇮🇱

    We review topics in searches for axion-like-particles (ALPs), covering material that is complementary to other recent reviews. The first half of our review covers ALPs in the extreme environments of neutron star cores, the magnetospheres of highly magnetized neutron stars (magnetars), and in neutron star mergers. The focus is on possible signals of ALPs in the photon spectrum of neutron stars and gravitational wave/electromagnetic signals from neutron star mergers. We then review recent developments in laboratory-produced ALP searches, focusing mainly on accelerator-based facilities including beam-dump type experiments and collider experiments. We provide a general-purpose discussion of the ALP search pipeline from production to detection, in steps, and our discussion is straightforwardly applicable to most beam-dump type and reactor experiments. We end with a selective look at the rapidly developing field of ultralight dark matter, specifically the formation of Bose-Einstein Condensates (BECs). We review the properties of BECs of ultralight dark matter and bridge these properties with developments in numerical simulations, and ultimately with their impact on experimental searches.

    hep-phastro-ph.HEnucl-thInt.J.Mod.Phys.D(2021)·38 citations
13. 13*

    New effect in wave-packet scattering of quantum fields

    Kenzo Ishikawa🇯🇵 · Kenji Nishiwaki🇮🇳 · Kin-ya Oda🇯🇵

    We report calculations of a wave-packet amplitude of the two-body scattering $\varphi \varphi \to \Phi \to \varphi \varphi$, which leads to the measured probability in realistic experiments. We elucidate the decay amplitude of $\Phi \to \varphi \varphi$ from this. In such an amplitude of wave packets, there are in and out time boundaries for the initial $\Phi$ and final $\varphi \varphi$ configurations, respectively. In this paper, we prove that the effect of the in time boundary of $\Phi \to \varphi \varphi$ emerges from $\varphi \varphi \to \Phi \to \varphi \varphi$ without assuming any time boundary \emph{a priori}. This effect has been overlooked in the standard plane-wave formulation and can exhibit distinct phenomena in wide areas of science. We confirm the result in different integration orders. The result is also interpreted as a Stokes phenomenon in the Lefschetz-thimble decomposition.

    ↳ hep-thhep-phPRD(2023)·11 citations
14. 14*

    Hot and dense quark-gluon plasma thermodynamics from holographic black holes

    Joaquin Grefa🇺🇸 · Jorge Noronha🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸 · Israel Portillo🇺🇸 · Claudia Ratti🇺🇸 · Romulo Rougemont🇧🇷

    We present new results on the equation of state and transition line of hot and dense strongly interacting QCD matter, obtained from a bottom-up Einstein-Maxwell-Dilaton holographic model. We considerably expand the previous coverage in baryon densities in this model by implementing new numerical methods to map the holographic black hole solutions onto the QCD phase diagram. We are also able to obtain, for the first time, the first-order phase transition line in a wide region of the phase diagram. Comparisons with the most recent lattice results for the QCD thermodynamics are also presented.

    ↳ nucl-thhep-phnucl-exPRD(2021)·107 citations
15. 15*

    Charmonium and Charmoniumlike States at the BESIII Experiment

    Chang-Zheng Yuan🇨🇳

    Charmonium is a bound state of a charmed quark and a charmed antiquark, and a charmoniumlike state is a resonant structure that contains a charmed quark and antiquark pair but has properties that are incompatible with a conventional charmonium state. While operating at center-of-mass energies from 2 to 4.9 GeV, the BESIII experiment can access a wide mass range of charmonium and charmoniumlike states, and has contributed significantly in this field. We review BESIII results involving conventional charmonium states, including the first observation of M1 transition $\psi (3686)\to \gamma {\eta }_c(2S)$ and the discovery of the ${\psi }_2(3823)$; and report on studies of charmoniumlike states, including the discoveries of the $Z_c(3900)$ and $Z_c(4020)$ tetraquark candidates, the resolution of the fine structure of the $Y(4260)$, the discovery of the new production process $e^{+}{e}^{-}\to \gamma X(3872)$, and the uncovering of strong evidence for the commonality among the $X(3872)$, $Y(4260)$, and $Z_c(3900)$ states. The prospects for further research at BESIII and proposed future facilities are also presented.

    ↳ hep-exhep-phNatl.Sci.Rev.(2021)·26 citations
16. 16*

    Lattice QCD calculation of the electroweak box diagrams for the kaon semileptonic decays

    Peng-Xiang Ma🇨🇳 · Xu Feng🇨🇳 · Mikhail Gorchtein🇩🇪 · Lu-Chang Jin🇺🇸 · Chien-Yeah Seng🇩🇪

    We present a lattice QCD calculation of the axial $\gamma W$-box diagrams relevant for the kaon semileptonic decays. We utilize a recently proposed method, which connects the electroweak radiative corrections in Sirlin's representation to that in chiral perturbation theory. It allows us to use the axial $\gamma W$-box correction in the SU(3) limit to obtain the low energy constants for chiral perturbation theory. From first principles our results confirm the previously used low energy constants provided by the minimal resonance model with a significant reduction in uncertainties.

    ↳ hep-lathep-exhep-phPRD(2021)·56 citations
17. 17*

    Measurements of the branching fractions of ${\Lambda }_c^{+}\to p\eta$ and ${\Lambda }_c^{+}\to p{\pi }^0$ decays at Belle

    Belle Collaboration: S. X. Li🇨🇳 · C. P. Shen🇨🇳 · I. Adachi🇯🇵 · J. K. Ahn🇰🇷 · H. Aihara🇯🇵 · D. M. Asner🇺🇸 · T. Aushev🇷🇺 · R. Ayad🇸🇦 · V. Babu🇩🇪 · S. Bahinipati🇮🇳 · P. Behera🇮🇳 · J. Bennett🇺🇸 and 194 other authors

    We report measurements of the branching fractions of singly Cabibbo-suppressed decays ${\Lambda }_c^{+}\to p\eta$ and ${\Lambda }_c^{+}\to p{\pi }^0$ using the full Belle data sample corresponding to an integrated luminosity of 980.6 $\mathrm{f}{\mathrm{b}}^{-1}$. The data were collected by the Belle detector at the KEKB $e^{+}$$e^{-}$ asymmetric-energy collider. A clear ${\Lambda }_c^{+}$ signal is seen in the invariant mass distribution of $p\eta$. The signal yield of the ${\Lambda }_c^{+}\to p\eta$ process is $7734\pm 263$; from this, we measure the ratio of branching fractions $\mathcal{B}({\Lambda }_c^{+}\to p\eta )/\mathcal{B}({\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+})=(2.258\pm 0.077(stat.)\pm 0.136(syst.))\times 10^{-2}$, from which we infer the branching fraction $\mathcal{B}({\Lambda }_c^{+}\to p\eta )=(1.42\pm 0.05(stat.)\pm 0.11(syst.))\times 10^{-3}$. In addition, no significant signal for ${\Lambda }_c^{+}\to p{\pi }^0$ is found so an upper limit on the branching fraction of $\mathcal{B}({\Lambda }_c^{+}\to p{\pi }^0)<8.0\times 10^{-5}$ at 90\% credibility level is set, more than three times better than the best current upper limit.

    ↳ hep-exhep-phPRD(2021)·33 citations
18. 18*

    Observational constraints and predictions of the interacting dark sector with field-fluid mapping

    Joseph P Johnson🇮🇳 · Archana Sangwan🇮🇳 · S. Shankaranarayanan (IIT Bombay)🇮🇳

    We consider an interacting field theory model that describes the dark energy - dark matter interaction. Only for a specific interaction term, this interacting field theory description has an equivalent interacting fluid description. For inverse power law potentials and linear interaction function, we show that the interacting dark sector model with field-fluid mapping is consistent with \textit{four cosmological data sets} -- Hubble parameter measurements (Hz), Baryonic Acoustic Oscillation data (BAO), Supernova Type Ia data (SN), and High redshift HII galaxy measurements (HIIG). More specifically, these data sets prefer a negative value of interaction strength in the dark sector and lead to consistent best-fit values of Hubble constant and other cosmological parameters. Having established that this interacting field theory model is consistent with cosmological observations, we obtain quantifying tools to distinguish between the interacting and non-interacting dark sector scenarios. We focus on the variation of the scalar metric perturbed quantities as a function of redshift related to structure formation, weak gravitational lensing, and the integrated Sachs-Wolfe effect. We show that the difference in the evolution becomes significant for $z<20$, for all length scales, and the difference peaks at smaller redshift values $z<5$. We then discuss the implications of our results for the upcoming missions.

    ↳ astro-ph.COgr-qchep-phJCAP(2022)·45 citations
19. 19*

    Hybrid star properties from an extended linear sigma model

    János Takátsy🇭🇺 · Péter Kovács🇭🇺 · György Wolf🇭🇺

    The equation of state provided by effective models of strongly interacting matter should comply with the restrictions imposed by current astrophysical observations on compact stars. Using the equation of state given by the (axial-)vector meson extended linear sigma model, we determine the mass-radius relation and study whether these restrictions are satisfied under the assumption that most of the star is filled with quark matter. We study the dependence of the mass-radius relation on the parameters of the model.

    ↳ nucl-thastro-ph.HEhep-phAstron.Nachr.(2021)·0 citations
20. 20*

    Can we observe the QCD phase transition-generated gravitational waves through pulsar timing arrays?

    Axel Brandenburg🇸🇪 · Emma Clarke🇺🇸 · Yutong He🇸🇪 · Tina Kahniashvili🇺🇸

    We perform numerical simulations of gravitational waves (GWs) induced by hydrodynamic and hydromagnetic turbulent sources that might have been present at cosmological quantum chromodynamic (QCD) phase transitions. For turbulent energies of about 4% of the radiation energy density, the typical scale of such motions may have been a sizable fraction of the Hubble scale at that time. The resulting GWs are found to have an energy fraction of about $10^{-9}$ of the critical energy density in the nHz range today and may already have been observed by the NANOGrav collaboration. This is further made possible by our findings of shallower spectra proportional to the square root of the frequency for nonhelical hydromagnetic turbulence. This implies more power at low frequencies than for the steeper spectra previously anticipated. The behavior toward higher frequencies depends strongly on the nature of the turbulence. For vortical hydrodynamic and hydromagnetic turbulence, there is a sharp drop of spectral GW energy by up to five orders of magnitude in the presence of helicity, and somewhat less in the absence of helicity. For acoustic hydrodynamic turbulence, the sharp drop is replaced by a power law decay, albeit with a rather steep slope. Our study supports earlier findings of a quadratic scaling of the GW energy with the magnetic energy of the turbulence and inverse quadratic scaling with the peak frequency, which leads to larger GW energies under QCD conditions.

    ↳ astro-ph.COhep-phphysics.flu-dynPRD(2021)·64 citations
21. 21*

    Nonlinear gravitational-wave memory from cusps and kinks on cosmic strings

    Alexander C. Jenkins🇬🇧 · Mairi Sakellariadou🇬🇧

    The nonlinear memory effect is a fascinating prediction of general relativity (GR), in which oscillatory gravitational-wave (GW) signals are generically accompanied by a monotonically-increasing strain which persists in the detector long after the signal has passed. This effect presents a unique opportunity to test GR in the dynamical and nonlinear regime. In this article we calculate the nonlinear memory signal associated with GW bursts from cusps and kinks on cosmic string loops, which are an important target for current and future GW observatories. We obtain analytical waveforms for the GW memory from cusps and kinks, and use these to calculate the "memory of the memory" and other higher-order memory effects. These are among the first memory observables computed for a cosmological source of GWs, with previous literature having focused almost entirely on astrophysical sources. Surprisingly, we find that the cusp GW signal diverges for sufficiently large loops, and argue that the most plausible explanation for this divergence is a breakdown in the weak-field treatment of GW emission from the cusp. This shows that previously-neglected strong gravity effects must play an important role near cusps, although the exact mechanism by which they cure the divergence is not currently understood. We show that one possible resolution is for these cusps to collapse to form primordial black holes (PBHs); the kink memory signal does not diverge, in agreement with the fact that kinks are not predicted to form PBHs. Finally, we investigate the prospects for detecting memory from cusps and kinks with GW observatories. We find that in the scenario where the cusp memory divergence is cured by PBH formation, the memory signal is strongly suppressed and is not likely to be detected. However, alternative resolutions of the cusp divergence may in principle lead to much more favourable observational prospects.

    ↳ gr-qcastro-ph.COhep-phClass.Quant.Grav.(2021)·17 citations
22. 22*

    Decoding Photons: Physics in the Latent Space of a BIB-AE Generative Network

    Erik Buhmann🇩🇪 · Sascha Diefenbacher🇩🇪 · Engin Eren🇩🇪 · Frank Gaede🇩🇪 · Gregor Kasieczka🇩🇪 · Anatolii Korol🇺🇦 · Katja Krüger🇩🇪

    Given the increasing data collection capabilities and limited computing resources of future collider experiments, interest in using generative neural networks for the fast simulation of collider events is growing. In our previous study, the Bounded Information Bottleneck Autoencoder (BIB-AE) architecture for generating photon showers in a high-granularity calorimeter showed a high accuracy modeling of various global differential shower distributions. In this work, we investigate how the BIB-AE encodes this physics information in its latent space. Our understanding of this encoding allows us to propose methods to optimize the generation performance further, for example, by altering latent space sampling or by suggesting specific changes to hyperparameters. In particular, we improve the modeling of the shower shape along the particle incident axis.

    ↳ physics.ins-dethep-exhep-phphysics.data-anEPJ Web Conf.(2021)·69 citations
23. 23*

    Dissecting the inner Galaxy with $\gamma$-ray pixel count statistics

    Francesca Calore🇫🇷 · Fiorenza Donato🇮🇹 · Silvia Manconi🇩🇪

    We combine adaptive template fitting and pixel count statistics in order to assess the nature of the Galactic center excess in Fermi-LAT data. We reconstruct the flux distribution of point sources well below the Fermi-LAT detection threshold, and measure their radial and longitudinal profiles in the inner Galaxy. We find that all point sources $and$ the bulge-correlated diffuse emission each contributes $\mathcal{O}$(10\%) of the total inner Galaxy emission, and disclose a potential sub-threshold point-source contribution to the Galactic center excess.

    ↳ astro-ph.HEhep-phPRL(2021)·51 citations
24. 24*

    Linear cosmological constraints on 2-body decaying dark matter scenarios and the $S_8$ tension

    Guillermo Franco Abellán🇫🇷 · Riccardo Murgia🇫🇷 · Vivian Poulin🇫🇷

    The '$S_8$ tension' is a longstanding discrepancy between the cosmic microwave background (CMB) and weak gravitational lensing determination of the amplitude of matter fluctuations, parametrized as $S_8\equiv {\sigma }_8({\Omega }_m/0.3{)}^{0.5}$, where ${\sigma }_8$ is the root mean square of matter fluctuations on a 8 $h^{-1}$Mpc scale, and ${\Omega }_m$ is the total matter abundance. It was recently shown that dark matter (DM) decaying into a massless (dark radiation) and a massive (warm DM) species, with a lifetime ${\Gamma }^{-1}\simeq 55(\epsilon /0.007{)}^{1.4}$ Gyrs -- where $\epsilon$ represent the mass-energy fraction transferred to the massless component -- can ease the tension. Thanks to a fast and accurate fluid approximation scheme for the warm species, we perform a comprehensive study of this 2-body decaying DM scenario, discussing in detail its dynamics and its impact on the CMB and linear matter power spectra. We then investigate the implications for the '$S_8$ tension' against a number of changes in the analysis: different $S_8$ priors, marginalization over the lensing information in Planck data, trading Planck high$-\ell$ polarization data for those from the SPTpol and ACTPol surveys, and the inclusion of the recent results from the Xenon1T collaboration. We conclude that the preference for decaying DM, apparent only when the $S_8$ value determined from weak lensing data is added to the analysis, does not sensibly degrade the fit to any of the cosmological data-sets considered, and that the model could potentially explain the anomalous electron recoil excess reported by the Xenon1T collaboration. Furthermore, we explictly show that while current CMB data alone are not sensitive enough to distinguish between standard CDM and decaying DM, next-generation CMB observations (CMB-S4) can unambiguously detect its signature.

    ↳ astro-ph.COhep-phPRD(2021)·91 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.