Thu·Jun 18, 2020Thursday·June 18, 2020

1. 01*

   New production channels for light dark matter in hadronic showers

   Andrea Celentano🇮🇹 · Luc Darmé🇮🇹 · Luca Marsicano🇮🇹 · Enrico Nardi🇮🇹

   Hadronic showers transfer a relevant amount of their energy to electromagnetic subshowers. We show that the generation of "secondary" dark photons in these sub-showers is significant and typically dominates the production at low dark photon masses. The resulting dark photons are however substantially less energetic than the ones originating from mesons decay. We illustrate this point both semi-analytically and through Monte Carlo simulations. Existing limits on vector-mediator scenarios for light dark matter are updated with the inclusion of the new production processes.

   hep-phhep-exPRD(2020)·42 citations
2. 02*

   Dynamical Evolution of Gravitational Leptogenesis

   Jamie I. McDonald🇩🇪 · Graham M. Shore🇬🇧

   Radiatively-induced gravitational leptogenesis is a potential mechanism to explain the observed matter-antimatter asymmetry of the universe. Gravitational tidal effects at the quantum loop level modify the dynamics of the leptons in curved spacetime and may be encoded in a low-energy effective action Seff. It has been shown in previous work how in a high-scale BSM theory the CP odd curvature-induced interactions in Seff modify the dispersion relations of leptons and antileptons differently in an expanding universe, giving rise to an effective chemical potential and a non-vanishing equilibrium lepton-antilepton asymmetry. In this paper, the CP even curvature interactions are shown to break lepton number current conservation and modify the evolution of the lepton number density as the universe expands. These effects are implemented in a generalised Boltzmann equation and used to trace the dynamical evolution of the lepton number density in different cosmological scenarios. The theory predicts a potentially significant gravitationally-induced lepton-antilepton asymmetry at very early times in the evolution of the universe.

   hep-phgr-qchep-thJHEP(2020)·9 citations
3. 03*

   Novel Heavy-Quark Physics Phenomena

   S.J. Brodsky🇺🇸 · G.I. Lykasov🇷🇺 · A.V. Lipatov🇷🇺 · J. Smiesko🇸🇰

   We review the current understanding of heavy quark parton distributions in nucleons and their impact on deep inelastic scattering, collider physics, and other processes at high energies. The determination of the heavy-quark parton distribution functions is particularly significant for the analysis of hard processes at LHC energies, including the forward rapidity high $x_{\mathrm{F}}$ domain. The contribution of "intrinsic" heavy quarks, which are multiply connected to the valence quarks of nucleons, is reviewed within non-perturbative physics which provides new information on the fundamental structure of hadrons in QCD. A new prediction for the non-perturbative intrinsic charm-anticharm asymmetry of the proton eigenstate has recently been obtained from a QCD lattice gauge theory calculation of the proton's $G_{\mathrm{E}}^p(Q^2)$ form factor. This form factor only arises from non-valence quarks and anti-quarks if they have different contributions in the proton's eigenstate. This result, together with the exclusive and inclusive connection and analytic constraints on the form of hadronic structure functions from Light-Front Holographic QCD (LFHQCD) predicts a significant non-perturbative $c(x,Q)-\bar{c}(x,Q)$ asymmetry in the proton structure function at high $x$, consistent with the dynamics predicted by intrinsic charm models. Recent ATLAS data on the associated production of prompt photons and charm-quark jets in $pp$ collisions at $\sqrt{s}=8$ TeV has provided new constraints on non-perturbative intrinsic charm and tests of the LGTH predictions. We also focus on other experimental observables which have high sensitivity to the intrinsic heavy contributions to PDFs.

   hep-phPPNP(2020)·20 citations
4. 04*

   Note on Thermalization of Non-resonantly Produced Sterile Neutrinos

   Graciela B. Gelmini🇺🇸 · Philip Lu🇺🇸 · Volodymyr Takhistov🇺🇸

   Using an analytic treatment, we discuss the parameter regions of large active-sterile neutrino mixing angles where sterile neutrinos produced in non-resonant flavour oscillations can approach thermalization in several cosmologies. We show that thermalization affects only large active-sterile neutrino mixing already rejected by different limits. Hence, the allowed sterile neutrino parameter regions are unaffected.

   hep-phastro-ph.COhep-exJCAP(2020)·6 citations
5. 05*

   Quantum nucleation of up-down quark matter and astrophysical implications

   Jing Ren🇨🇳 · Chen Zhang🇨🇦

   Quark matter with only $u$ and $d$ quarks ($ud$QM) might be the ground state of baryonic matter at large baryon number $A>A_{\min }$. With $A_{\min }\gtrsim 300$, this has no direct conflict with the stability of ordinary nuclei. An intriguing test of this scenario is to look for quantum nucleation of $ud$QM inside neutron stars due to their large baryon densities. In this paper, we study the transition rate of cold neutron stars to $ud$ quark stars ($ud$QSs) and the astrophysical implications, considering the relevant theoretical uncertainties and observational constraints. It turns out that a large portion of parameter space predicts an instantaneous transition, and so the observed neutron stars are mostly $ud$QSs. We find this possibility still viable under the recent gravitational wave and pulsar observations, although there are debates on its compatibility with some observations that involve complicated structure of quark matter. The tension could be partially relieved in the two-families scenario, where the high-mass stars ($M\gtrsim 2M_{\odot }$) are all $ud$QSs and the low-mass ones ($M\sim 1.4M_{\odot }$) are mostly hadronic stars. In this case, the slow transition of the low-mass hadronic stars points to a very specific class of hadronic models with moderately stiff EOSs, and $ud$QM properties are also strongly constrained.

   hep-phastro-ph.HEgr-qcnucl-thPRD(2020)·34 citations
6. 06*

   Higgs boson decay to lepton pair and photon and possible non-Hermiticity of the Yukawa interaction

   V.A. Kovalchuk · A.Yu. Korchin

   The production of lepton pairs in the Higgs boson decay $h\to {\ell }^{+}{\ell }^{-}\gamma$ is studied. The emphasis is put on the structure of the Higgs boson interaction with the fermions. This interaction is chosen as a mixture of the scalar and pseudo-scalar couplings, and, in addition, it is supposed to be non-Hermitian. We study prediction of this model for the observables in the $h\to {\ell }^{+}{\ell }^{-}\gamma$ decay for the $e^{+}{e}^{-}$, ${\mu }^{+}{\mu }^{-}$ and ${\tau }^{+}{\tau }^{-}$ pairs. The differential decay width and lepton forward-backward asymmetry are calculated as functions of the dilepton invariant mass for several sets of $hf\bar{f}$ coupling constants. The influence of non-Hermitian $hf\bar{f}$ interaction on the forward-backward asymmetry is studied, and large influence of a possible non-Hermiticity of the Higgs interaction with the top quarks on forward-backward asymmetry for $e^{+}{e}^{-}$ and ${\mu }^{+}{\mu }^{-}$ pairs is stressed.

   hep-phUkr.Phys.J.(2017)·2 citations
7. 07*

   Implications of CP invariants for flavoured hybrid neutrino mass matrix

   Madan Singh🇮🇳

   In the present paper, I have re-examined the weak basis invariants at low energies, proposed by C. Jarlskog and Branco et. al, respectively, in their earlier analyses, after confronting them with the assumptions of two zeros and an equality between arbitrary non-zero elements in the Majorana neutrino mass matrix in the flavoured basis. This particular conjecture is found to be experimentally feasible as shown by S. Dev and D. Raj in their recent work. The present analysis attempts to find the necessary and sufficient condition for CP invariance for each experimentally viable ansätz, pertaining to the model along with some important implications.

   hep-phPTEP(2020)·1 citation
8. 08*

   Double parton distributions of the pion

   Wojciech Broniowski🇵🇱 · Enrique Ruiz Arriola🇪🇸

   We present a calculation of valence double parton distributions of the pion in the framework of chiral quark models. The result obtained at the low-energy quark model scale is particularly simple, where in the chiral limit a factorized form follows, $D(x_1,x_2,\vec{q})=\delta (1-x_1-x_2)F(\vec{q})$ with $x_{1,2}$ standing for the longitudinal momentum fractions of the valence quark and antiquark, and $\vec{q}$ denotes the relative transverse momentum. For $\vec{q}=\vec{0}$ the result satisfies the Gaunt-Sterling sum rules. The QCD evolution to higher scales is carried out within the dDGLAP framework. We argue that the ratios of the valence Mellin moments $⟨x_1^n{x}_2^m⟩/⟨x_1^n⟩⟨x_2^m⟩$, which do not depend on the dDGLAP evolution, provide particularly convenient measures of the longitudinal correlations between the partons. Such ratios could be probed in future lattice QCD simulations.

   hep-phhep-latActa Phys.Polon.Supp.(2021)·0 citations
9. 09*

   Applications of the Nambu--Jona-Lasinio model to the partonic structure of the pion

   Wojciech Broniowski🇵🇱 · Enrique Ruiz Arriola🇪🇸

   We present a brief review of results of chiral quark models for soft matrix elements in the pion state, appearing in high-energy processes as well as accessible in present and future lattice studies. A particular attention is paid to the recently explored double parton distribution functions of the pion.

   hep-phhep-latEur.Phys.J.ST(2020)·1 citation
10. 10*

    Gauge-covariant diagonalization of $\pi$-$a_1$ mixing and the resolution of a low energy theorem

    A. A. Osipov🇷🇺 · M. M. Khalifa🇷🇺 · B. Hiller🇵🇹

    Using a recently proposed gauge covariant diagonalization of $\pi a_1$-mixing we show that the low energy theorem $F^{\pi }=e{f}_{\pi }^2{F}^{3\pi }$ of current algebra, relating the anomalous form factor $F_{\gamma \to {\pi }^{+}{\pi }^0{\pi }^{-}}=F^{3\pi }$ and the anomalous neutral pion form factor $F_{{\pi }^0\to \gamma \gamma }=F^{\pi }$, is fulfilled in the framework of the Nambu-Jona-Lasinio (NJL) model, solving a long standing problem encountered in the extension including vector and axial-vector mesons. At the heart of the solution is the presence of a $\gamma \pi \bar{q}q$ vertex which is absent in the conventional treatment of diagonalization and leads to a deviation from the vector meson dominance (VMD) picture. It contributes to a gauge invariant anomalous tri-axial (AAA) vertex as a pure surface term.

    hep-phActa Phys.Polon.Supp.(2021)·1 citation
11. 11*

    Inelastic Meson-Meson Scattering in Hadronic Matter

    Xiao-Ming Xu🇨🇳 · H. J. Weber🇺🇸

    We review studies of inelastic meson-meson scattering. In nonperturbative schemes with chiral-perturbation-theory Lagrangians and in models based on effective meson Lagrangians, inelastic meson-meson scattering leads to the successful identification of resonances in meson-meson reactions, adequate inclusion of final state interactions in particle decays, and so on. For mesons of which each consists of a quark and an antiquark, inelastic meson-meson scattering may be caused by quark-antiquark annihilation, quark-antiquark creation, quark interchange, and quark-antiquark annihilation and creation. In transition amplitudes for meson-meson scattering mesonic quark-antiquark relative-motion wave functions depend on hadronic matter, and transition potentials are given in perturbative quantum chromodynamics. Via transition amplitudes the cross sections for inelastic meson-meson scattering depend on the temperature of hadronic matter. Some prominent temperature dependence of the cross sections has been found. Inelastic meson-meson scattering becomes even more significant in proton-proton collisions and lead-lead collisions at the Large Hadron Collider.

    hep-phMod.Phys.Lett.A(2020)·4 citations
12. 12*

    Light gravitino dark matter: LHC searches and Hubble tension

    Yuchao Gu🇨🇳 · Maxim Khlopov🇷🇺 · Lei Wu🇨🇳 · Jin Min Yang🇨🇳 · Bin Zhu🇨🇳

    The recent measurements of the cosmological parameter $H_0$ from the direct local observations and the inferred value from the Cosmic Microwave Background show $\sim 4\sigma$ discrepancy. This may indicate new physics beyond the standard $\Lambda$CDM. We investigate the keV gravitino dark matter that has a small fraction of non-thermal component (e.g. from the late decay of NLSP bino) under various cosmological constraints. We find such a scenario is highly predictive and can be tested by searching for the dilepton plus missing energy events at the LHC. Besides, we also discuss its implication for Hubble tension, however, which can be reduced to $3\sigma$ level marginally.

    hep-phastro-ph.COPRD(2020)·32 citations
13. 13*

    Two-component source to explain $\Lambda$ and $\bar{\Lambda }$ global polarization in non-central heavy-ion collisions

    A. Ayala (1,2)🇲🇽 · E. Cuautle (1)🇲🇽 · I. Domínguez (3)🇲🇽 · I. Maldonado (3)🇲🇽 · J. Salinas (1)🇲🇽 · M. E. Tejeda-Yeomans (4,5) ((1) Instituto de Ciencias Nucleares Universidad Nacional Autónoma de México, (2) Centre for Theoretical and Mathematical Physics and Department of Physics University of Cape Town, (3) Facultad de Ciencias Físico-Matemáticas Universidad Autónoma de Sinaloa, (4) Facultad de Ciencias-CUICBAS Universidad de Colima, (5) Departamento de Física Universidad de Sonora)🇲🇽

    The STAR Beam Energy Scan program has found a difference in the global polarization of $\Lambda$s and $\bar{\Lambda }$s produced in $Au+Au$ collisions. This difference is larger for lower center of mass collision energies. In this work we show that a two-component source, consisting of a high density core and a lower density corona, can describe quantitatively the $\Lambda$ and $\bar{\Lambda }$ polarization as a function of collision energy.

    hep-phJ.Phys.Conf.Ser.(2020)·2 citations
14. 14*

    XENON1T excess from anomaly-free ALP dark matter and its implications for stellar cooling anomaly

    Fuminobu Takahashi🇯🇵 · Masaki Yamada🇯🇵 · Wen Yin🇯🇵

    Recently, an anomalous excess was found in the electronic recoil data collected at the XENON1T experiment. The excess may be explained by an axion-like particle (ALP) with mass of a few keV and a coupling to electron of $g_{ae}\sim 10^{-13}$, if the ALP constitutes all or some fraction of local dark matter (DM). In order to satisfy the X-ray constraint, the ALP coupling to photons must be significantly suppressed compared to that to electrons. This strongly suggests that the ALP has no anomalous couplings to photons, i.e., there is no U(1)${}_{\mathrm{PQ}}$-U(1)${}_{\mathrm{em}}$-U(1)${}_{\mathrm{em}}$ anomaly. We show that such anomaly-free ALP DM predicts an X-ray line signal with a definite strength through the operator arising from threshold corrections, and compare it with the projected sensitivity of the ATHENA X-ray observatory. The abundance of ALP DM can be explained by the misalignment mechanism, or by thermal production if it constitutes a part of DM. In particular, we find that the anomalous excess reported by the XENON1T experiment as well as the stellar cooling anomalies from white dwarfs and red giants can be explained simultaneously better when the ALP constitutes about 10\% of DM. As concrete models, we revisit the leptophilic anomaly-free ALP DM considered in [Phys.Lett.B 734 (2014) 178-182] as well as an ALP model based on a two Higgs doublet model in the supplemental material.

    hep-phastro-ph.COPRL(2020)·131 citations
15. 15*

    Muon g-2 and EDM experiments as muonic dark matter detectors

    Ryan Janish🇺🇸 · Harikrishnan Ramani🇺🇸

    The detection of ultralight dark matter through interactions with nucleons, electrons, and photons has been explored in depth. In this work we propose to use precision muon experiments, specifically muon g-2 and electric dipole moment measurements, to detect ultralight dark matter that couples predominantly to muons. We set direct, terrestrial limits on DM-muon interactions using existing g-2 data, and show that a time-resolved reanalysis of ongoing and upcoming precession experiments will be sensitive to dark matter signals. Intriguingly, we also find that the current muon g-2 anomaly can be explained by a spin torque applied to muons from a pseudoscalar dark matter background that induces an oscillating electric dipole moment for the muon. This explanation may be verified by a time-resolved reanalysis.

    hep-phastro-ph.COhep-exPRD(2020)·28 citations
16. 16*

    Electromagnetic Waves in Hot and Dense Media

    Samina Masood🇺🇸

    It is known that the finite temperature and density (FTD) corrections increase the electron mass, charge and modify the properties of the emitted radiation. All the signals, travelling through the astronomical bodies, carry over the information of their origin and bring minor details about the structure and composition of the source. It has been noticed that temperatures of the early universe add physically measureable mass to electron and large chemical potential lead to an increase in mass as well. However, the QED coupling is slowly increased with temperature but is decreased with increasing chemical potential in superdense systems. Due to the strong relationship between the properties of electromagnetic signals and composition of the material of the propagating objects, we propose to incorporate the modified signal properties to analyze the astronomical data and its interpretation. Existence of different phases of stellar matter at the quantum scale indicates frequent phase transitions for rapidly rotating superdense materials. This information is related to the fact that the allowed range of temperature and chemical potential for a physical system is determined by the signal properties and properties changes with the material as well..

    hep-phastro-ph.HE1 citation
17. 17*

    Pion-photon transition form factor in LCSR and tests of asymptotics

    N. G. Stefanis🇩🇪

    We study the pion-photon transition form factor (TFF) $F^{\gamma \ast \gamma {\pi }^0}(Q^2)$ using a state-of-the art implementation of light cone sum rules (LCSRs) within fixed-order QCD perturbation theory. The spectral density in the dispersion relation includes all currently known radiative corrections up to the next-to-next-to-leading-order (NNLO) and all twist contributions up to order six. Predictions for the TFF are obtained for various pion distribution amplitudes (DAs) of twist two, including two-loop evolution which accounts for heavy-quark mass thresholds. The influence of the main theoretical uncertainties is quantified in order to enable a more realistic comparison with the data. The characteristics of various pion DAs are analyzed in terms of the conformal coefficients $a_2$ and $a_4$ in comparison with the $1\sigma$ and $2\sigma$ error regions of the data and the most recent lattice constraints on $a_2$ with NLO and NNLO accuracy. Our results provide more stringent bounds on the variation of the pion DA and illuminate the corresponding asymptotic behavior of the calculated TFF.

    hep-phhep-exPRD(2020)·35 citations
18. 18*

    A technique for natural gauge boson masses

    Benjamin Koch🇨🇱 · Cristobal Laporte🇨🇱

    In this work, a novel mechanism for spontaneous symmetry breaking is presented. This mechanism avoids quadratic divergencies and is thus capable of addressing the hierarchy problem in gauge theories. Using the scale-dependent effective action ${\Gamma }_k$ minimally coupled to a gravitational sector, variational parameter setting is applied. This provides a mass and vacuum expectation value as a function of the constants arising in the low scale expansion of Newtons' and cosmological couplings. A comparison with experimental data, such as the Higgs mass, allows putting restrictions on these constants. With this generic approach one can compare with explicit candidates for an effective field theory of gravity. As an example, we use the asymptotic safety scenario, where we find restrictions on the matter content of the theory.

    ↳ hep-thgr-qchep-phPRD(2021)·5 citations
19. 19*

    Entropy production due to adiabatic particle creation in a holographic dissipative cosmology

    Nobuyoshi Komatsu🇯🇵

    Cosmological adiabatic particle creation results in the generation of irreversible entropy. The evolution of this entropy is examined in a flat Friedmann--Robertson--Walker universe at late times, using a dissipative model with a power-law term (proportional to the power of the Hubble parameter $H$). In a dissipative universe, the irreversible entropy included in the Hubble volume is found to be proportional to $H^{-1}$, unlike for the case of the Bekenstein--Hawking entropy on the horizon of the universe. In addition, the evolution of the horizon entropy is examined, extending the previous analysis of a non-dissipative universe [Phys.\ Rev.\ D \textbf{100}, 123545 (2019) (arXiv:1911.08306)]. In the present model, the generalized second law of thermodynamics is always satisfied, whereas the maximization of entropy is satisfied under specific conditions. The dissipative universe should be constrained by the entropy maximization as if the universe behaves as an ordinary, isolated macroscopic system. The thermodynamic constraints are likely to be consistent with constraints on a transition from a decelerating universe to an accelerating universe.

    ↳ gr-qcastro-ph.COhep-phPRD(2020)·12 citations
20. 20*

    Tests of conservation laws in post-Newtonian gravity with binary pulsars

    Xueli Miao🇨🇳 · Junjie Zhao🇨🇳 · Lijing Shao🇨🇳 · Norbert Wex🇩🇪 · Michael Kramer🇩🇪 · Bo-Qiang Ma🇨🇳

    General relativity is a fully conservative theory, but there exist other possible metric theories of gravity. We consider non-conservative ones with a parameterized post-Newtonian (PPN) parameter, ${\zeta }_2$. A non-zero ${\zeta }_2$ induces a self-acceleration for the center of mass of an eccentric binary pulsar system, which contributes to the second time derivative of the pulsar spin frequency, $\ddot{\nu }$. In our work, using the method in Will (1992), we provide an improved analysis with four well-timed, carefully-chosen binary pulsars. In addition, we extend Will's method and derive ${\zeta }_2$'s effect on the third time derivative of the spin frequency, $\stackrel{...}{\nu }$. For PSR B1913+16, the constraint from $\stackrel{...}{\nu }$ is even tighter than that from $\ddot{\nu }$. We combine multiple pulsars with Bayesian inference, and obtain an upper limit, $\left|{\zeta }_2\right|<1.3\times 10^{-5}$ at 95% confidence level, assuming a flat prior in ${\log }_{10}\left|{\zeta }_2\right|$. It improves the existing bound by a factor of three. Moreover, we propose an analytical timing formalism for ${\zeta }_2$. Our simulated times of arrival with simplified assumptions show binary pulsars' capability in limiting ${\zeta }_2$, and useful clues are extracted for real data analysis in future. In particular, we discover that for PSRs B1913+16 and J0737$-$3039A, $\stackrel{...}{\nu }$ can yield more constraining limits than $\ddot{\nu }$.

    ↳ gr-qcastro-ph.HEhep-phApJ(2020)·10 citations
21. 21*

    Combined Limit on the Photon Mass with Nine Localized Fast Radio Bursts

    Jun-Jie Wei🇨🇳 · Xue-Feng Wu🇨🇳

    A nonzero-mass hypothesis for the photon can produces a frequency-dependent dispersion of light, which results in arrival-time differences of photons with different frequencies originating from a given transient source. Extragalactic fast radio bursts (FRBs), with their low frequency emissions, short time durations, and long propagation distances, are excellent astrophysical probes to constrain the rest mass of the photon $m_{\gamma }$. However, the derivation of a limit on $m_{\gamma }$ is complicated by the similar frequency dependences of dispersion expected from the plasma and nonzero photon mass effects. If a handful measurements of redshift for FRBs are available, the different redshift dependences of the plasma and photon mass contributions to the dispersion measure (DM) might be able to break dispersion degeneracy in testing the photon mass. For now, nine FRBs with redshift measurements have been reported, which can turn this idea into reality. Taking into account the DM contributions from both the plasma and a possible photon mass, we use the data on the nine FRBs to derive a combined limit of $m_{\gamma }\le 7.1\times 10^{-51}\mathrm{kg}$, or equivalently $m_{\gamma }\le 4.0\times 10^{-15}\mathrm{eV}/c^2$ at 68\% confidence level, which is essentially as good as or represents a factor of 7 improvement over previous limits obtained by the single FRBs. Additionally, a reasonable estimation for the DM contribution from the host galaxy, $\mathrm{D}{\mathrm{M}}_{\mathrm{host}}$, can be simultaneously achieved in our analysis. The rapid progress in localizing FRBs will further tighten the constraints on both $m_{\gamma }$ and $\mathrm{D}{\mathrm{M}}_{\mathrm{host}}$.

    ↳ astro-ph.HEgr-qchep-phRes.Astron.Astrophys.(2020)·21 citations
22. 22*

    Excess Electronic Recoil Events in XENON1T

    E. Aprile🇺🇸 · J. Aalbers🇸🇪 · F. Agostini🇮🇹 · M. Alfonsi🇩🇪 · L. Althueser🇩🇪 · F. D. Amaro🇵🇹 · V. C. Antochi🇸🇪 · E. Angelino🇮🇹 · J. R. Angevaare🇳🇱 · F. Arneodo🇦🇪 · D. Barge🇸🇪 · L. Baudis🇨🇭 and 127 other authors

    We report results from searches for new physics with low-energy electronic recoil data recorded with the XENON1T detector. With an exposure of 0.65 t-y and an unprecedentedly low background rate of $76\pm 2$ events/(t y keV) between 1 and 30 keV, the data enables sensitive searches for solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter. An excess over known backgrounds is observed at low energies and most prominent between 2 and 3 keV. The solar axion model has a 3.4$\sigma$ significance, and a 3D 90% confidence surface is reported for axion couplings to electrons, photons, and nucleons. This surface is inscribed in the cuboid defined by $g_{ae}<3.8\times 10^{-12}$, $g_{ae}{g}_{an}^{eff}<4.8\times 10^{-18}$, and $g_{ae}{g}_{a\gamma }<7.7\times 10^{-22}Ge{V}^{-1}$, and excludes either $g_{ae}=0$ or $g_{ae}{g}_{a\gamma }=g_{ae}{g}_{an}^{eff}=0$. The neutrino magnetic moment signal is similarly favored over background at 3.2$\sigma$ and a confidence interval of ${\mu }_{\nu }\in (1.4,2.9)\times 10^{-11}{\mu }_B$ (90% C.L.) is reported. Both results are in strong tension with stellar constraints. The excess can also be explained by $\beta$ decays of tritium at 3.2$\sigma$ with a trace amount that can neither be confirmed nor excluded with current knowledge of its production and reduction mechanisms. The significances of the solar axion and neutrino magnetic moment hypotheses are reduced to 2.0$\sigma$ and 0.9$\sigma$, respectively, if an unconstrained tritium component is included in the fitting. With respect to bosonic dark matter, the excess favors a monoenergetic peak at ($2.3\pm 0.2$) keV (68% C.L.) with a 3.0$\sigma$ global (4.0$\sigma$ local) significance. We also consider the possibility that ${}^{37}$Ar may be present in the detector and yield a 2.82 keV peak. Contrary to tritium, the ${}^{37}$Ar concentration can be tightly constrained and is found to be negligible.

    ↳ hep-exastro-ph.COhep-phPRD(2020)·784 citations
23. 23*

    Spectral functions in the ${\varphi }^4$-theory from the spectral DSE

    Jan Horak🇩🇪 · Jan M. Pawlowski🇩🇪 · Nicolas Wink🇩🇪

    We develop a non-perturbative functional framework for computing real-time correlation functions in strongly correlated systems. The framework is based on the spectral representation of correlation functions and dimensional regularisation. Therefore, the non-perturbative spectral renormalisation setup here respects all symmetries of the theories at hand. In particular this includes space-time symmetries as well as internal symmetries such as chiral symmetry, and gauge symmetries. Spectral renormalisation can be applied within general functional approaches such as the functional renormalisation group, Dyson-Schwinger equations, and two- or $n$-particle irreducible approaches. As an application we compute the full, non-perturbative, spectral function of the scalar field in the ${\varphi }^4$-theory in $2+1$ dimensions from spectral Dyson-Schwinger equations. We also compute the $s$-channel spectral function of the full ${\varphi }^4$-vertex in this theory.

    ↳ hep-thhep-phPRD(2020)·57 citations
24. 24*

    High-frequency Graviton from Inflaton Oscillation

    Yohei Ema🇩🇪 · Ryusuke Jinno🇩🇪 · Kazunori Nakayama🇯🇵

    We point out that there is a high-frequency tail of the stochastic inflationary gravitational wave background that scales as $f^{-1/2}$ with frequency $f$. This contribution comes from the graviton vacuum fluctuation amplified by the inflaton coherent oscillation during the reheating stage. It contains information on inflaton properties such as the inflaton mass as well as the thermal history of the early Universe.

    ↳ astro-ph.COhep-phJCAP(2020)·56 citations
25. 25*

    What does the Marked Power Spectrum Measure? Insights from Perturbation Theory

    Oliver H.E. Philcox🇺🇸 · Elena Massara🇨🇦 · David N. Spergel🇺🇸

    The marked power spectrum is capable of placing far tighter constraints on cosmological parameters (particularly the neutrino mass) than the conventional power spectrum. What new information does it contain beyond conventional statistics? Through the development of a perturbative model, we find that the mark induces a significant coupling between non-Gaussianities, which are usually found on small scales, and large scales, leading to the additional information content. The model is derived in the context of one-loop perturbation theory and validated by comparison to $N$-body simulations across a variety of mark parameters. At moderate redshifts, including for massive neutrino cosmologies, the theory is in good agreement with the simulations. The importance of non-linear gravitational effects on the large-scale spectra complicates the modeling as there is no well-defined convergence radius of the theory at low $z$. Extension to higher perturbative order and biased tracers is possible via a similar approach, and a simple model of the latter is shown to yield promising results. The theory becomes non-perturbative at redshift zero for small smoothing scales, with important contributions from higher-order terms: these will need to be studied before the full power of this tool can be realized.

    ↳ astro-ph.COastro-ph.GAastro-ph.IMhep-ph+1PRD(2020)·52 citations
26. 26*

    Geometries with mismatched branes

    Andreas Karch🇺🇸 · Lisa Randall🇺🇸

    We study Randall-Sundrum two brane setups with mismatched brane tensions. For the vacuum solutions, boundary conditions demand that the induced metric on each of the branes is either de Sitter, Anti-de Sitter, or Minkowski. For incompatible boundary conditions, the bulk metric is necessarily time-dependent. This introduces a new class of time-dependent solutions with the potential to address cosmological issues and provide alternatives to conventional inflationary (or contracting) scenarios. We take a first step in this paper toward such solutions. One important finding is that the resulting solutions can be very succinctly described in terms of an effective action involving only the induced metric on either one of the branes and the radion field. But the full geometry cannot necessarily be simply described with a single coordinate patch. We concentrate here on the time-dependent solutions but argue that supplemented with a brane stabilization mechanism one can potentially construct interesting cosmological models this way. This is true both with and without a brane stabilization mechanism.

    ↳ hep-thhep-phJHEP(2020)·37 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.