Fri·Aug 7, 2020Friday·August 7, 2020

1. 01*

   Dark matter assisted lepton anomalous magnetic moments and neutrino masses

   Sudip Jana🇩🇪 · Vishnu P.K.🇺🇸 · Werner Rodejohann🇩🇪 · Shaikh Saad🇺🇸

   We propose a framework that addresses the origin of neutrino mass, explains the observed discrepancies in the electron and the muon anomalous magnetic moments (AMMs) data and incorporates the dark matter (DM) relic abundance. Both the neutrino mass and the lepton AMMs are generated at one-loop level mediated by a common set of beyond the Standard Model (SM) states. In this class of models, the SM is extended with vector-like charged fermion and scalar multiplets, all odd under an imposed ${\mathcal{Z}}_2$ symmetry, which stabilizes the fermionic or scalar DM candidate residing in one of them. Two scalar multiplets appear in the AMM loops, thus allowing for different signs of their contributions, in agreement with the observed discrepancies which are of opposite sign for electron and muon. The vector-like fermions give rise to large new physics contributions to the lepton AMMs via chirally enhanced terms that are proportional to their mass. To demonstrate the viability of this framework, we perform a detailed study of a particular model for which a fit to the neutrino masses and mixing together with lepton AMMs are provided. Furthermore, DM phenomenology and collider signatures are explored.

   hep-phhep-exPRD(2020)·76 citations
2. 02*

   The common origin of the family mass hierarchy and CP violation from flavour-dependent vacuum for quarks and leptons

   Ying Zhang🇨🇳

   We rewrite the Yukawa interactions of the standard model in terms of flavour-dependent vacuum structure to address the family mass hierarchy and CP violation in both the quark sector and lepton sector. It is realized for the first time that the Lagrangian only includes the same number of degrees of freedom as phenomenological observables with no requirement of extra particles or any new symmetry. The quark and lepton mass hierarchy arises as a natural result of the close-to-flat vacuum in flavour space. The CP violation in CKM and PMNS is explained as a general quantum phase between weak gauge eigenstates and Yukawa interaction states. The mechanism is proven by reproduction of all current quark/lepton mass data and the CKM/PMNS flavour mixings.

   hep-phInt.J.Mod.Phys.A(2021)·2 citations
3. 03*

   Ultralight vector dark matter search with auxiliary length channels of gravitational wave detectors

   Yuta Michimura🇯🇵 · Tomohiro Fujita🇯🇵 · Soichiro Morisaki🇯🇵 · Hiromasa Nakatsuka🇯🇵 · Ippei Obata🇩🇪

   Recently, a considerable amount of attention has been given to the search for ultralight dark matter by measuring the oscillating length changes in the arm cavities of gravitational wave detectors. Although gravitational wave detectors are extremely sensitive for measuring the differential arm length changes, the sensitivity to dark matter is largely attenuated, as the effect of dark matter is mostly common to arm cavity test masses. Here, we propose to use auxiliary length channels, which measure the changes in the power and signal recycling cavity lengths and the differential Michelson interferometer length. The sensitivity to dark matter can be enhanced by exploiting the fact that auxiliary interferometers are more asymmetric than two arm cavities. We show that the sensitivity to $U(1{)}_{B-L}$ gauge boson dark matter with masses below $7\times 10^{-14}$ eV can be greatly enhanced when our method is applied to a cryogenic gravitational wave detector KAGRA, which employs sapphire test masses and fused silica auxiliary mirrors. We show that KAGRA can probe more than an order of magnitude of unexplored parameter space at masses around $1.5\times 10^{-14}$ eV, without any modifications to the existing interferometer.

   hep-phastro-ph.COastro-ph.IMgr-qc+1PRD(2020)·50 citations
4. 04*

   Revisiting Jet Clustering Algorithms for New Higgs Boson Searches in Hadronic Final States

   Amit Chakraborty🇮🇳 · Srinandan Dasmahapatra🇬🇧 · Henry Day-Hall🇬🇧 · Billy Ford🇬🇧 · Shubhani Jain🇬🇧 · Stefano Moretti🇬🇧 · Emmanuel Olaiya🇬🇧 · Claire Shepherd-Themistocleous🇬🇧

   We assess the performance of different jet-clustering algorithms, in the presence of different resolution parameters and reconstruction procedures, in resolving fully hadronic final states emerging from the chain decay of the discovered Higgs boson into pairs of new identical Higgs states, the latter in turn decaying into bottom-antibottom quark pairs. We show that, at the Large Hadron Collider (LHC), both the efficiency of selecting the multi-jet final state and the ability to reconstruct from it the masses of the Higgs bosons (potentially) present in an event sample depend strongly on the choice of acceptance cuts, jet-clustering algorithm as well as its settings. Hence, we indicate the optimal choice of the latter for the purpose of establishing such a benchmark Beyond the SM (BSM) signal.

   hep-phEPJC(2022)·14 citations
5. 05*

   Baryon fluctuations in extended linear sigma model

   Gyozo Kovacs🇭🇺 · Peter Kovacs🇭🇺

   The existence and the location of the critical end point (CEP) between the crossover and the first order part of the chiral phase transition in the phase diagram of the strongly interacting matter is a heavily studied area of recent particle physics. The baryon number fluctuations and related quantities such as kurtosis and other susceptibility ratios, that are assumed to be good signatures of CEP, are calculated in an (axial)vector meson extended $(2+1)$ flavor Polyakov linear sigma model (EL$\sigma$M) at zero and finite ${\mu }_B$ . It is compared with the results of lattice as well as other effective model calculations. Divergence of the kurtosis is found at the critical end point.

   hep-phActa Phys.Polon.Supp.(2021)·1 citation
6. 06*

   Centrality, transverse momentum and collision energy dependence of the Tsallis parameters in relativistic heavy-ion collisions

   Rajendra Nath Patra🇺🇦 · Bedangadas Mohanty🇮🇳 · Tapan K. Nayak🇨🇭

   The thermodynamic properties of matter created in high-energy heavy-ion collisions have been studied in the framework of the non-extensive Tsallis statistics. The transverse momentum ($p_{\mathrm{T}}$)~spectra of identified charged particles (pions, kaons, protons) and all charged particles from the available experimental data of Au-Au collisions at the Relativistic Heavy Ion Collider (RHIC) energies and Pb-Pb collisions at the Large Hadron Collider (LHC) energies are fitted by the Tsallis distribution. The fit parameters, $q$ and $T$ measure the degree of deviation from an equilibrium state and the effective temperature of the thermalized system, respectively. The $p_{\mathrm{T}}$~spectra are well described by the Tsallis distribution function from peripheral to central collisions for the wide range of collision energies, from $\sqrt{s_{\mathrm{NN}}}$ = 7.7 GeV to 5.02 TeV. The extracted Tsallis parameters are found to be dependent on the particle species, collision energy, centrality, and fitting ranges in $p_{\mathrm{T}}$. For central collisions, both $q$ and $T$ depend strongly on the fit ranges in $p_{\mathrm{T}}$. For most of the collision energies, $q$ remains almost constant as a function of centrality, whereas $T$ increases from peripheral to central collisions. For a given centrality, $q$ systematically increases as a function of collision energy whereas $T$ has a decreasing trend. A profile plot of $q$ and $T$ with respect to collision energy and centrality shows an anti-correlation between the two parameters.

   hep-phnucl-thEur.Phys.J.Plus(2021)·25 citations
7. 07*

   Constraining $t\to u$ flavor changing neutral Higgs coupling at the LHC

   Wei-Shu Hou🇹🇼 · Ting-Hsiang Hsu🇹🇼 · Tanmoy Modak🇹🇼

   We study the constraints on $t\to u$ flavor changing neutral Higgs (FCNH) coupling, and how it may be explored further at the Large Hadron Collider (LHC). In the general two Higgs doublet model, such transitions can be induced by a nonzero ${\rho }_{tu}$ Yukawa coupling. We show that such couplings can be constrained by existing searches at the LHC for $m_H$, $m_A$ and, $m_{H^{+}}$ in the sub-TeV range, where $H$, $A$ and $H^{+}$ are the exotic $CP$-even, $CP$-odd and charged scalars. We find that a dedicated $ug\to tH/tA\to tt\bar{u}$ search can probe the available parameter space of ${\rho }_{tu}$ down to a few percent level for $200\text{mbox}GeV\lesssim m_H,m_A\lesssim 600$ GeV, with discovery possible at high luminosity. Effects of how other extra top Yukawa couplings, such as ${\rho }_{tc}$ and ${\rho }_{tt}$, dilute the sensitivity of the ${\rho }_{tu}$ probe are discussed.

   hep-phhep-exPRD(2020)·21 citations
8. 08*

   Correlating $h\to {\mu }^{+}{\mu }^{-}$ to the Anomalous Magnetic Moment of the Muon via Leptoquarks

   Andreas Crivellin🇨🇭 · Dario Mueller🇨🇭 · Francesco Saturnino🇨🇭

   Recently, both ATLAS and CMS measured the decay $h\to {\mu }^{+}{\mu }^{-}$, finding a signal strength with respect to the Standard Model expectation of $1.2\pm 0.6$ and $1.19\begin{array}{c}+0.41+0.17\\ -0.39-0.16\end{array}$, respectively. This provides, for the first time, evidence that the Standard Model Higgs couples to second generation fermions. This measurement is particularly interesting in the context of the intriguing hints for lepton flavor universality violation, accumulated within recent years, as new physics explanations could also be tested in the $h\to {\mu }^{+}{\mu }^{-}$ decay mode. Leptoquarks are prime candidates to account for the flavor anomalies. In particular, they can provide the necessary chiral enhancement (by a factor $m_t/m_{\mu }$) to address $a_{\mu }$ with TeV scale new physics. In this letter we point out that such explanations of $a_{\mu }$ also lead to enhanced effects in $h\to {\mu }^{+}{\mu }^{-}$ and we examine the correlations between $h\to {\mu }^{+}{\mu }^{-}$ and $a_{\mu }$ within leptoquark models. We find that the effect in the branching ratio of $h\to {\mu }^{+}{\mu }^{-}$ ranges from several percent up to a factor three, if one aims at accounting for $a_{\mu }$ at the $2\sigma$ level. Hence, the new ATLAS and CMS measurements already provide important constraints on the parameter space, rule out specific $a_{\mu }$ explanations and will be very important to test the flavor anomalies in the future.

   hep-phhep-exnucl-exnucl-thPRL(2021)·83 citations
9. 09*

   Relativistic Friedrichs-Lee model and quark-pair creation model

   Zhi-Yong Zhou🇨🇳 · Zhiguang Xiao🇨🇳

   In this paper, we present how the Friedrichs-Lee model could be extended to the relativistic scenario and be combined with the relativistic quark pair creation model in a consistent way. This scheme could be applied to study the "unquenched" effect of the meson spectra. As an example, if the lowest $J^{PC}=0^{++}$ $(u\bar{u}+d\bar{d})/\sqrt{2}$ bound state in the potential model is coupled to the $\pi \pi$ continuum, two resonance poles could be found from the scattering amplitude for the continuum states. One of them could correspond to the $f_0(500)/\sigma$ and the other probably $f_0(1370)$. This scheme might shed more light on why extra states could appear in the hadron spectrum other than the prediction of the quark potential model.

   hep-phhep-exnucl-thEPJC(2020)·14 citations
10. 10*

    Future CEvNS experiments as probes of lepton unitarity and light-sterile neutrinos

    O. G. Miranda🇲🇽 · D. K. Papoulias🇬🇷 · O. Sanders🇲🇽 · M. Tórtola🇪🇸 · J. W. F. Valle🇪🇸

    We determine the sensitivities of short-baseline coherent elastic neutrino-nucleus scattering (CE$\nu$NS) experiments using a pion decay at rest neutrino source as a probe for nonunitarity in the lepton sector, as expected in low-scale type-I seesaw schemes. We also identify the best configuration for probing light sterile neutrinos at future ton-scale liquid argon CE$\nu$NS experiments, estimating the projected sensitivities on the sterile neutrino parameters. Possible experimental setups at the Spallation Neutron Source, Lujan facility and the European Spallation Source are discussed. Provided that systematic uncertainties remain under control, we find that CE$\nu$NS experiments will be competitive with oscillation measurements in the long run.

    hep-phPRD(2020)·72 citations
11. 11*

    Exclusive vector meson production in electron-ion collisions at the EIC, LHeC and FCC-$eh$

    Victor P. Goncalves🇧🇷 · Daniel E. Martins🇧🇷 · Celso R. Sena🇧🇷

    The exclusive vector meson production in electron-ion collisions for the energies of the future colliders is investigated. We present predictions for the coherent and incoherent $\varphi$ and $J/\psi$ production in $eAu$ collisions considering the possible states of nucleon configurations in the nuclear wave function and taking into account of the non-linear corrections to the QCD dynamics. The cross sections and transverse momentum distributions are estimated assuming the energies of the Electron-Ion Collider (EIC), Large Hadron Electron Collider (LHeC) and Future Circular Collider (FCC-$eh$). Our results indicate that a future experimental analysis of these processes can shed light on the modeling of the gluon saturation effects and constrain the description of the QCD dynamics at high energies.

    hep-phnucl-thNPA(2020)·13 citations
12. 12*

    Interpretation of the XENON1T excess in the model with decaying sterile neutrinos

    V. V. Khruschov🇷🇺

    The phenomenological model with three active and three sterile neutrinos is used for interpretation of the observed XENON1T excess of electronic recoil events in the 1 -- 7 keV energy region. Assuming two sterile neutrinos with appropriate mass values decay while the third sterile neutrino is stable it is possible to explain the observed energy spectrum of electronic recoil events. Moreover using this approach three peaks in the 1 -- 7 keV energy region are predicted. Dark bosons have to mix to only a small extent with photons which can be emitted in this region. The possible existence of the three light sterile neutrinos may have perceptible influence on some phenomena in neutrino physics, astrophysics and cosmology.

    hep-ph10 citations
13. 13*

    Machine learning-based event generator for electron-proton scattering

    Y. Alanazi🇺🇸 · P. Ambrozewicz🇺🇸 · M. Battaglieri🇮🇹 · A. N. Hiller Blin🇩🇪 · M.P. Kuchera🇺🇸 · Y. Li🇺🇸 · T. Liu🇺🇸 · R.E. McClellan🇺🇸 · W. Melnitchouk🇺🇸 · E. Pritchard🇺🇸 · M. Robertson🇺🇸 · N. Sato🇺🇸 · R. Strauss🇺🇸 · L. Velasco🇺🇸

    We present a new machine learning-based Monte Carlo event generator using generative adversarial networks (GANs) that can be trained with calibrated detector simulations to construct a vertex-level event generator free of theoretical assumptions about femtometer scale physics. Our framework includes a GAN-based detector folding as a fast-surrogate model that mimics detector simulators. The framework is tested and validated on simulated inclusive deep-inelastic scattering data along with existing parametrizations for detector simulation, with uncertainty quantification based on a statistical bootstrapping technique. Our results provide for the first time a realistic proof-of-concept to mitigate theory bias in inferring vertex-level event distributions needed to reconstruct physical observables.

    hep-phhep-exnucl-thPRD(2022)·29 citations
14. 14*

    Effects of QCD critical point on light nuclei production

    Kai-Jia Sun🇺🇸 · Che Ming Ko🇺🇸 · Feng Li🇨🇳

    Using the nucleon coalescence model, which can naturally take into account the correlations in the nucleon density distribution, we study the effects of QCD critical point on light nuclei production in relativistic heavy-ion collisions. We find that the yield ratio $N_t{N}_p/N_d^2$ of proton ($p$), deuteron ($d$) and triton ($t$) increases monotonically with the nucleon density correlation length, which is expected to increase significantly near the critical point in the QCD phase diagram. Our study thus demonstrates that the yield ratio $N_t{N}_p/N_d^2$ can be used as a sensitive probe of the QCD critical phenomenon. We further discuss the relation between the QCD phase transitions in heavy-ion collisions and the possible non-monotonic behavior of \pdt~in its collision energy dependence.

    ↳ nucl-thhep-phPLB(2021)·27 citations
15. 15*

    Gravitational and electromagnetic radiation from binary black holes with electric and magnetic charges: Circular orbits on a cone

    Lang Liu🇨🇳 · Øyvind Christiansen🇳🇴 · Zong-Kuan Guo🇨🇳 · Rong-Gen Cai🇨🇳 · Sang Pyo Kim🇨🇳

    We derive the equations of motion of dyonic black hole binaries with electric and magnetic charges and explore features of static orbits. By using a Newtonian method with the inclusion of radiation reaction, we calculate the total emission rate of energy and angular momentum due to gravitational radiation and electromagnetic radiation for circular orbits. Moreover, we obtain the evolutions of orbits and calculate merger times of dyonic binaries. We show that electric and magnetic charges significantly suppress the merger times of dyonic binaries. Our results provide rich information about dyonic binaries and can be used to test black holes with magnetic charges.

    ↳ gr-qchep-phPRD(2020)·56 citations
16. 16*

    Probing Axion-like Particles via CMB Polarization

    Tomohiro Fujita🇯🇵 · Yuto Minami🇯🇵 · Kai Murai🇯🇵 · Hiromasa Nakatsuka🇯🇵

    Axion-like particles (ALPs) rotate the linear polarization of photons through the ALP-photon coupling and convert the cosmic microwave background (CMB) $E$-mode to the $B$-mode. We derive the relation between the ALP dynamics and the rotation angle by assuming that the ALP $\varphi$ has a quadratic potential, $V=m^2{\varphi }^2/2$. We compute the current and future sensitivities of CMB observations to the ALP-photon coupling $g$, which can reach $g=4\times 10^{-21}{\mathrm{GeV}}^{-1}$ for $10^{-32}\mathrm{eV}\lesssim m\lesssim 10^{-28}\mathrm{eV}$ and extensively exceed the other searches for any mass $m\lesssim 10^{-25}\mathrm{eV}$. We find that the fluctuation of the ALP field at the observer, which has been neglected in previous studies, can induce significant isotropic rotation of the CMB polarization. The measurements of isotropic and anisotropic rotation allow us to put bounds on relevant quantities such as the ALP mass $m$ and the ALP density parameter ${\Omega }_{\varphi }$. In particular, if LiteBIRD detects anisotropic rotation, we obtain the lower bound on the tensor-to-scalar ratio as $r>5\times 10^{-9}$.

    ↳ astro-ph.COhep-phPRD(2021)·64 citations
17. 17*

    Note on initial conditions for small-field inflation

    Ignatios Antoniadis🇫🇷 · Auttakit Chatrabhuti🇹🇭 · Hiroshi Isono🇹🇭 · Spyros Sypsas🇹🇭

    We show that initial conditions for small-field inflation can be determined quantum mechanically by introducing a suitable flattened region in the scalar potential. The inflaton is then driven towards the slow-roll attractor solution exponentially fast, desensitising inflation from the initial velocity and partially evading the so-called overshoot problem. We give an explicit example in the context of hilltop inflation by introducing an ultra slow-roll plateau around the maximum of the potential and analyse its effect on the phase-space trajectories.

    ↳ hep-thgr-qchep-phPRD(2020)·6 citations
18. 18*

    Probing Dark Matter Self-interaction with Ultra-faint Dwarf Galaxies

    Kohei Hayashi🇯🇵 · Masahiro Ibe🇯🇵 · Shin Kobayashi🇯🇵 · Yuhei Nakayama🇯🇵 · Satoshi Shirai🇯🇵

    Self-interacting dark matter (SIDM) has gathered growing attention as a solution to the small scale problems of the collisionless cold dark matter (DM). We investigate the SIDM using stellar kinematics of 23 ultra-faint dwarf (UFD) galaxies with the phenomenological SIDM halo model. The UFDs are DM-dominated and have less active star formation history. Accordingly, they are the ideal objects to test the SIDM, as their halo profiles are least affected by the baryonic feedback processes. We found no UFDs favor non-zero self-interaction and some provide stringent constraints within the simple SIDM modeling. Our result challenges the simple modeling of the SIDM, which urges further investigation of the subhalo dynamical evolution of the SIDM.

    ↳ astro-ph.COhep-phPRD(2021)·43 citations
19. 19*

    Fate of false vacua in holographic first-order phase transitions

    Francesco Bigazzi🇮🇹 · Alessio Caddeo🇮🇹 · Aldo L. Cotrone🇮🇹 · Angel Paredes🇪🇸

    Using the holographic correspondence as a tool, we study the dynamics of first-order phase transitions in strongly coupled gauge theories at finite temperature. Considering an evolution from the large to the small temperature phase, we compute the nucleation rate of bubbles of true vacuum in the metastable phase. For this purpose, we find the relevant configurations (bounces) interpolating between the vacua and we compute the related effective actions. We start by revisiting the compact Randall-Sundrum model at high temperature. Using holographic renormalization, we compute the kinetic term in the effective bounce action, that was missing in the literature. Then, we address the full problem within the top-down Witten-Sakai-Sugimoto model. It displays both a confinement/deconfinement and a chiral symmetry breaking/restoration phase transition which, depending on the model parameters, can happen at different critical temperatures. For the confinement/deconfinement case we perform the numerical analysis of an effective description of the transition and also provide analytic expressions using thick and thin wall approximations. For the chiral symmetry transition, we implement a variational approach that allows us to address the challenging non-linear problem stemming from the Dirac-Born-Infeld action.

    ↳ hep-thhep-phJHEP(2020)·65 citations
20. 20*

    The analytic structure of the lattice Landau gauge gluon and ghost propagators

    Alexandre F. Falcão🇵🇹 · Orlando Oliveira🇵🇹 · Paulo J. Silva🇵🇹

    Starting from the lattice Landau gauge gluon and ghost propagator data we use a sequence of Padé approximants, identify the poles and zeros for each approximant and map them into the analytic structure of the propagators. For the Landau gauge gluon propagator the Padé analysis identifies a pair of complex conjugate poles and a branch cut along the negative real axis of the Euclidean $p^2$ momenta. For the Landau gauge ghost propagator the Padé analysis shows a single pole at $p^2=0$ and a branch cut also along the negative real axis of the Euclidean $p^2$ momenta. The method gives precise estimates for the gluon complex poles, that agree well with other estimates found in the literature. For the branch cut the Padé analysis gives, at least, a rough estimate of the corresponding branch point.

    ↳ hep-lathep-phhep-thPRD(2020)·47 citations
21. 21*

    Excited and exotic bottomonium spectroscopy from lattice QCD

    Sinéad M. Ryan🇮🇪 · David J. Wilson🇬🇧

    We explore the spectrum of excited and exotic bottomonia using lattice QCD. Highly excited states are identified with masses up to 11,000 MeV, many of which can be grouped into supermultiplets matching those of the quark model while exotic spin--parity--charge-conjugation quantum numbers $J^{PC}=0^{+-},1^{-+},2^{+-}$ that cannot be formed from $\bar{q}q$ alone are also identified. Single-meson operator constructions are used that have good $J^{PC}$ in the continuum, these are found to overlap well onto heavy quark states with $J\le 4$. A continuum $J^{PC}$ is assigned to each level, based on the distribution amongst lattice irreps and dominant operator overlaps. States with a dominant gluonic component are identified and form a hybrid supermultiplet with $J^{PC}=(0,1,2{)}^{-+},1^{--}$, approximately 1500 MeV above the ground-state ${\eta }_b$, similar to previous computations with light, strange and charm quark systems.

    ↳ hep-lathep-phJHEP(2021)·46 citations
22. 22*

    Investigation of Quark Distributions in a Family of Pentaquarks using the Thomas-Fermi Quark Model

    Mohan Giri🇺🇸 · Suman Baral🇳🇵 · Gopi C. Kaphle🇳🇵 · Nirmal Dangi🇳🇵 · Sudip Shiwakoti🇺🇸 · Leonardo Bardomero🇺🇸 · Paul Lashomb🇺🇸 · Walter Wilcox🇺🇸

    Using the Thomas-Fermi quark model, a collective, spherically symmetric density of states is created to represent a gas of interacting fermions with various degeneracies at zero temperature. Over a family of multi-pentaquarks, color interaction probabilities are obtained after averaging over all the possible configurations. It is found that three different Thomas-Fermi functions are necessary for light, charm, and anti-charm quarks. These are assumed to be linearly related by proportionality constants resulting in consistency conditions. We analyze these conditions and find that they lead to an interesting pattern of spherical quark distributions.

    ↳ nucl-thhep-phCommun.Theor.Phys.(2021)·2 citations
23. 23*

    Axion Gegenschein: Probing Back-scattering of Astrophysical Radio Sources Induced by Dark Matter

    Oindrila Ghosh🇩🇪 · Jordi Salvado🇪🇸 · Jordi Miralda-Escudé🇪🇸

    We investigate a novel technique for the astrophysical detection of axions or axion-like particles in the dark matter halo of the Milky Way based on stimulated decay of axions, which we call axion gegenschein emission. Photons from the brightest known radio sources with a frequency equal to half the axion mass stimulate axion decay while propagating through the dark matter halo, causing radio emission in a direction precisely opposite to the incoming photon in the axion rest-frame and creating a countersource for every radio source, with an image smoothed by the dark matter velocity dispersion. We calculate the flux of the axion gegenschein countersource of Cygnus A, the brightest extragalactic radio source, and the limits that can be set with SKA to the axion-photon coupling constant $g_{a\gamma }$. We find this method to be more powerful than previous proposals based on searching for radio emission from axion decay in nearby dwarf galaxies or the Milky Way. The forecasted limits remain considerably higher than predictions from QCD axion models, and limits that can be set with laboratory searches of radio waves generated in resonant cavities with strong magnetic fields similar to the ADMX experiment, although this observation would directly measure a column density of dark matter through the Galactic halo and is therefore not affected by possible substructure in the dark matter distribution.

    ↳ astro-ph.COhep-ph24 citations
24. 24*

    Resonant gravitational waves in dynamical Chern-Simons-axion gravity

    Tomohiro Fujita🇯🇵 · Ippei Obata🇩🇪 · Takahiro Tanaka🇯🇵 · Kei Yamada🇯🇵

    In this paper, we consider dynamical Chern-Simons gravity with the identification of the scalar field coupled though the Pontryagin density with the axion dark matter, and we discuss the effects of the parametric resonance on gravitational waves (GWs). When we consider GWs in a coherently oscillating axion cloud, we confirm that significant resonant amplification of GWs occurs in a narrow frequency band, and the amplification is restricted to the late epoch after the passage of the incident waves. We also identify the condition that an axion cloud spontaneously emits GWs. Once we take into account the randomness of the spatial phase distribution of the axion oscillations, we find that the amplification is suppressed compared with the coherent case, but significant amplification of GWs can still occur. We also examine whether or not the amplification of GWs is possible in the present universe, taking into account the history of the universe. We find that resonant amplification is difficult to be tested from GW observations in the standard scenario of the axion DM model, in which the axion is the dominant component of DM. However, there is some parameter window in which the resonant amplification of GWs might be observed, if the axion is subdominant component of DM, and the axion cloud formation is delayed until the Hubble rate becomes much smaller than the axion mass.

    ↳ gr-qcastro-ph.COhep-phhep-thClass.Quant.Grav.(2021)·11 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.