Thu·Feb 24, 2022Thursday·February 24, 2022

1. 01*

   Axion Electrodynamics and the Axionic Casimir Effect

   Iver Brevik🇳🇴

   A general scheme for axion electrodynamics is given, in which a surrounding medium of constant permittivity and permeability is assumed. Then, as an application we give simple numerical estimates for the electromagnetic current density produced by the electrically neutral time-dependent axions $a=a(t)$ in a strong magnetic field. As is known, the assumption $a=a(t)$ is common under astrophysical conditions. In the third part of the paper, we consider the implications by assuming instead an axion amplitude $a(z)$ depending on one coordinate $z$ only. If such an axion field is contained within two large metal plates one obtains an axion-generated splitting of the eigenmodes for the dispersion relation. These modes yield equal, though opposite, contributions to the pressure on the plates. We calculate the magnitude of the splitting effect, in a simple one-dimensional model.

   hep-phhep-thUniverse(2021)·17 citations
2. 02*

   $t\bar{t}b\bar{b}$ at the LHC: On the size of off-shell effects and prompt $b$-jet identification

   Giuseppe Bevilacqua🇭🇺 · Huan-Yu Bi🇩🇪 · Heribertus Bayu Hartanto🇬🇧 · Manfred Kraus🇺🇸 · Michele Lupattelli🇩🇪 · Malgorzata Worek🇩🇪

   We investigate full off-shell effects in $t\bar{t}b\bar{b}$ production in the dilepton channel at the LHC with the center-of-mass energy $\sqrt{s}=13$ TeV. Specifically, we compute NLO QCD corrections to the $pp\to e^{+}{\nu }_e{\mu }^{-}{\bar{\nu }}_{\mu }b\bar{b}b\bar{b}+X$ process and provide a prescription for $b$-jet identification to distinguish prompt $b$ jets from $b$ jets originating from the decay of the top quarks. As an important irreducible background to $pp\to t\bar{t}H(H\to b\bar{b})$, $t\bar{t}$ production in association with two prompt $b$ jets is a primary source of uncertainty in the measurement of $t\bar{t}H(H\to b\bar{b})$. In quantifying full off-shell effects, we perform comparisons between the state-of-the-art full off-shell computation and the calculation in the narrow width approximation. The former includes all double-, single- and non-resonant Feynman diagrams, interferences as well as finite-width effects of the top quarks and $W$ gauge bosons. The latter restricts the unstable top quarks and $W$ gauge bosons to on-shell states and includes for the first time NLO QCD corrections to both production and decays. We observe that full off-shell effects are subdominant compared to the scale uncertainties for the integrated fiducial cross section and for the majority of differential observables in the phase-space regions that we investigated. However, for a number of observables related to beyond the Standard Model searches, full off-shell effects are significant. Furthermore, with our $b$-jet labelling prescription, the prompt $b$ jets and the $b$ jets from top-quark decays can be successfully disentangled.

   hep-phhep-exPRD(2023)·27 citations
3. 03*

   Cold and hot nuclear matter effects on $J/\psi$ production at RHIC-BES energies

   Jiaxing Zhao🇨🇳 · Pengfei Zhuang🇨🇳

   Integrated and differential $J/\psi R_{AA}$ are systematically studied in Au-Au collisions at RHIC-BES energies in a transport approach, including cold and hot nuclear effects respectively in the initial condition and the collision terms. With decreasing energy, while the temperature, life time and size of the QGP fireball decrease, the nuclear absorption of the initially produced charmonia is more and more strong, and the nuclear shadowing effect on charmonium regeneration goes to anti-shadowing first and then to shadowing again. As a competition between the cold and hot nuclear effects, the QGP phase is still important for charmonium production at $\sqrt{s_{NN}}$=200, 62.4, 54.4 and 39 GeV but becomes negligible at $\sqrt{s_{NN}}$=14.5 GeV.

   hep-phPRC(2022)·13 citations
4. 04*

   Cosmological constraints on heavy sterile neutrinos

   L. Mastrototaro🇮🇹

   We consider heavy sterile neutrinos ${\nu }_s$, with mass in the range 10 MeV $\lesssim m_s\lesssim m_{\pi }\sim 135$ MeV, thermally produced in the early universe and freezing out after the QCD phase transition. The existence of these neutrinos may alter the value of the effective number of neutrino species $N_{\mathrm{eff}}$, measured by the cosmic microwave background (CMB), and the ${}^4$He production during the BBN. We provide a detailed account of the solution of the relevant Boltzmann equations and we identify the parameter space constrained by current Planck satellite data and forecast the parameter space probed by future Stage-4 ground-based CMB (CMB-S4) observations.

   hep-phJ.Phys.Conf.Ser.(2021)·0 citations
5. 05*

   Magnetic moment of the $X_1(2900)$ state in the diquark-antidiquark picture

   U. Özdem🇹🇷 · K. Azizi🇮🇷

   Motivated by the discovery of fully open-flavor tetraquark states $X_0(2900)$ and $X_1(2900)$ by the LHCb Collaboration, the magnetic dipole moment of the $X_1(2900)$ state with the quantum numbers $J^P=1^{-}$ is determined in the diquark-antidiquark picture using the light-cone sum rules. The numerical result is obtained as ${\mu }_{X_1}=0.79_{-0.39}^{+0.36}{\mu }_N$. The magnetic moments of hadrons encompasses useful knowledge on the distributions of charge and magnetization their inside, which can be used to better understand their geometrical shapes and quark-gluon organizations. The observation of the $X_0(2900)$ and $X_1(2900)$ as the first two fully open-flavor multiquark states has opened a new window for investigation of the exotic states. The obtained results in the present study may shed light on the future experimental and theoretical searches on the properties of fully open-flavor multiquark states.

   hep-phhep-exhep-latEPJA(2022)·20 citations
6. 06*

   Charge-asymmetric correlations in elastic lepton- and antilepton-proton scattering from real photon emission

   A. Afanasev🇺🇸 · A. Ilyichev🇧🇾

   Observation of charge asymmetry by comparing electron and positron, or muon and anti-muon, scattering on a hadronic target presently serves as an experimental tool to study two-photon exchange effects. In addition to two-photon exchange, real photon emission also contributes to the charge asymmetry. We present a theoretical formalism, explicit expressions, and a numerical analysis of hard photon emission for the charge asymmetry in lepton- and antilepton-proton scattering. Different kinematic conditions are considered, namely, either fixed transferred momentum squared or a fixed lepton scattering angle. The infrared divergence from real photon emission is treated by the Bardin-Shumeiko technique and canceled with the soft part of the two-photon exchange contribution extracted and calculated using Tsai approach. All final expressions are obtained beyond the ultrarelativistic approximation with respect to the lepton mass that allows to evaluate numerically of the considered effects not only for ultrarelativistic leptons (JLab) and but for moderately relativistic (MUSE) kinematics, too.

   hep-phEPJA(2022)·5 citations
7. 07*

   Some aspects of impact of the Electron Ion Collider on particle physics at the Energy Frontier

   S.V. Chekanov🇺🇸 · S. Magill🇺🇸

   This overview describes several science cases at the Electron-Ion-Collider (EIC) experiment which are traditional to general particle physics. It has an emphasis on connections between future measurements at the EIC and the physics topics explored at high-energy frontier colliders. It covers several selected topics, such as parton density functions, multi-quarks states, correlations of final-state particles, precision QCD measurements and forward jet physics. We will discuss possible EIC measurements that can improve previous experimental results obtained at high-energy (HEP) experiments.

   hep-ph4 citations
8. 08*

   Impact of QCD uncertainties on antiproton spectra from dark-matter annihilation

   Adil Jueid🇰🇷 · Jochem Kip🇳🇱 · Roberto Ruiz de Austri🇪🇸 · Peter Skands🇦🇺

   Dark-matter particles that annihilate or decay can undergo complex sequences of processes, including strong and electromagnetic radiation, hadronisation, and hadron decays, before particles that are stable on astrophysical time scales are produced. Antiprotons produced in this way may leave footprints in experiments such as AMS--02. Several groups have reported an excess of events in the antiproton flux in the rigidity range of $10$--$20$ GV. However, the theoretical modeling of baryon production is not straightforward and relies in part on phenomenological models in Monte Carlo event generators. In this work, we assess the impact of QCD uncertainties on the spectra of antiprotons from dark-matter annihilation. As a proof-of-principle, we show that for a two-parameter model that depends only on the thermally-averaged annihilation cross section ($⟨\sigma v⟩$) and the dark-matter mass ($M_{\chi }$), QCD uncertainties can affect the best-fit mass by up to $\sim 14\%$ (with large uncertainties for large DM masses), depending on the choice of $M_{\chi }$ and the annihilation channel ($b\bar{b}$ or $W^{+}{W}^{-}$), and $⟨\sigma v⟩$ by up to $\sim 10\%$. For comparison, changes to the underlying diffusion parameters are found to be within $1\%$--$5\%$, and the results are also quite resilient to the choice of cosmic-ray propagation model. These findings indicate that QCD uncertainties need to be included in future DM analyses. To facilitate full-fledged analyses, we provide the spectra in tabulated form including QCD uncertainties and code snippets to perform mass interpolations and quick DM fits. The code can be found in this \href{https://github.com/ajueid/qcd-dm.github.io.git}{github} repository.

   hep-phastro-ph.HEJCAP(2023)·25 citations
9. 09*

   Mini-review: Expectations for supersymmetry from the string landscape

   Howard Baer🇺🇸 · Vernon Barger🇺🇸 · Shadman Salam🇺🇸 · Dibyashree Sengupta🇹🇼

   In this mini-review, we summarize a variety of findings pertaining to consequences of the landscape of string theory for supersymmetry (SUSY) phenomenology. The idea is to adopt the MSSM as the most parsimonious 4-d low energy EFT after string compactification but where the scale of SUSY breaking is as yet undetermined. A power-law landscape draw to large soft terms is tempered by the requirement that the derived value of the weak scale lie within the anthropic window of Agrawal {\it et al.} (ABDS). Such a set-up predicts a light Higgs mass m_h~ 125 GeV with sparticles generally beyond LHC bounds. We discuss consequences for LHC searches: light higgsinos, highly mixed TeV-scale top squarks, same-sign diboson events and m_{\tg}~ 2-5 TeV. We expect dark matter to consist of an axion/higgsino-like WIMP admixture.

   hep-ph9 citations
10. 10*

    $\mathcal{O}({\alpha }_s^2)$ corrections to $J/\psi +{\chi }_{c0,1,2}$ production at $B$ factories

    Wen-Long Sang🇨🇳 · Feng Feng🇨🇳 · Yu Jia🇨🇳 · Zhewen Mo🇨🇳 · Jia-Yue Zhang🇨🇳

    We compute the $\mathcal{O}({\alpha }_s^2)$ corrections to the exclusive channels $e^{+}{e}^{-}\to J/\psi +{\chi }_{cJ}$ ($J=0,1,2$) at $\sqrt{s}=10.58$ GeV within the nonrelativistic QCD (NRQCD) factorization framework. The validity of NRQCD factorization at $\mathcal{O}({\alpha }_s^2)$ has been confirmed for these double-charmonium exclusive production processes. We analyze the impact of the $\mathcal{O}({\alpha }_s^2)$ corrections on the polarized and unpolarized cross sections, as well as the $J/\psi$ angular distributions, which largely reduce the renormalization scale dependence but increase the $\mathcal{O}({\alpha }_s)$ NRQCD predictions to some extent for ${\chi }_{c0,1}$. With high numerical accuracy, our predictions for $\sigma (J/\psi +{\chi }_{c1,2})$ through $\mathcal{O}({\alpha }_s^2)$ are compatible with the upper limit of the \texttt{Belle} measurement. Although the theoretical prediction for $\sigma (J/\psi +{\chi }_{c0})$ is consistent with both \texttt{Belle} and \texttt{BaBar} measurements within uncertainties, there still exists serious tension between the predicted and the measured profiles for the $J/\psi$ angular distribution. Regarding the bright observation prospect of the $e^{+}{e}^{-}\to J/\psi +{\chi }_{c1,2}$ channels in \texttt{Belle 2} experiment, it is interesting to compare the future measurements with our NRQCD predictions. The more accurate measurement of $e^{+}{e}^{-}\to J/\psi +{\chi }_0$ at \texttt{Belle 2} will also help to clarify the long-standing puzzle of $J/\psi$ angular distribution.

    hep-phhep-exPLB(2023)·17 citations
11. 11*

    Production of $P_c$(4312) state in electron-proton collisions

    In Woo Park🇰🇷 · Su Houng Lee🇰🇷 · Sungtae Cho🇰🇷 · Yongsun Kim🇰🇷

    We study the cross sections for the electro-production of $P_c(4312)$ particle, a recently discovered pentaquark state, in electron-proton collisions assuming possible quantum numbers to be $J^P={\frac{1}{2}}^{\pm },{\frac{3}{2}}^{\pm }$. $\sqrt{s}$ is set to the energy of the future Electron Ion Collider at Brookhaven National Laboratory, in order to asses the possibility of the measurement in this facility. One can discriminate the spin of $P_c(4312)$ by comparing the pseudorapidity distribution in two different polarization configurations for proton and electron beams. Furthermore, the parity of $P_c(4312)$ can be discerned by analyzing the decay angle in the $P_c\to p+J/\psi$ channel. As the multiplicity of $P_c$ production in our calculation is large, the EIC can be considered as a future facility for precision measurement of heavy pentaquarks.

    hep-phnucl-exnucl-thPRD(2022)·8 citations
12. 12*

    Confronting dark fermion with a doubly charged Higgs in the left-right symmetric model

    Shyamashish Dey🇮🇳 · Purusottam Ghosh🇮🇳 · Santosh Kumar Rai🇮🇳

    We consider a fermionic dark matter (DM) in the left-right symmetric framework by introducing a pair of vector-like (VL) doublets in the particle spectrum. The stability of the DM is ensured through an unbroken ${\mathcal{Z}}_2$ symmetry. We explore the parameter space of the model compatible with the observed relic density and direct and indirect detection cross sections. The presence of charged dark fermions opens up an interesting possibility for the doubly charged Higgs signal at LHC and ILC. The signal for the doubly charged scalar decaying into the dark sector is analyzed in multilepton final states for a few representative parameter choices consistent with DM observations.

    hep-phEPJC(2022)·10 citations
13. 13*

    Optical Theorem, Crossing Property and Derivative Dispersion Relations: Implications on the Asymptotic Behavior of ${\sigma }_{tot}(s)$ and $\rho (s)$

    S. D. Campos (Federal University of São Carlos)🇧🇷 · V. A. Okorokov (National Research Nuclear University MEPhI)🇷🇺

    In this paper, one presents some results concerning the behavior of the total cross section and $\rho$-parameter at asymptotic energies in proton-proton ($pp$) and antiproton-proton ($\bar{p}p$) collisions. For this intent, we consider three of the main theoretical results in high energy physics: the crossing property, the derivative dispersion relation, and the optical theorem. The use of such machinery allows the analytic formulas for wide set of the measured global scattering parameters and some important relations between them. The suggested parameterizations approximate simultaneously the energy dependence for total cross section and $\rho$-parameter for $pp$ and $\bar{p}p$ with statistically acceptable quality in multi-TeV region. Also the qualitative description is obtained for important interrelations, namely difference, sum and ratio of the antiparticle-particle and particle-particle total cross sections. Despite the reduced number of experimental data for the total cross section and $\rho$-parameter in TeV-scale, which turns any prediction for the beginning of the asymptotic domain a hard task, the fitting procedures indicates that asymptotia lies in the energy range 25.5-130 TeV. Moreover, in the asymptotic regime, one obtains ${\alpha }_{\mathbb{P}}=1$. Detailed quantitative study of energy behavior of measured scattering parameters and their combinations in ultra-high energy domain indicates that the scenario with the generalized formulation of the Pomeranchuk theorem is more favorable with respect to the original formulation of this theorem.

    hep-phCPC(2022)·2 citations
14. 14*

    On-shell versus curvature mass parameter fixing schemes in the quark-meson model and its phase diagrams

    Suraj Kumar Rai🇮🇳 · Vivek Kumar Tiwari🇮🇳

    We compute and compare the effective potential and phase structure for the quark-meson model in an extended mean-field approximation (e-MFA) when vacuum one loop quark fluctuations are included and the model parameters are fixed using different renormalization prescriptions.When the quark one loop vacuum divergence is regularized under the minimal subtraction scheme,the model setting of the parameter fixing using the curvature masses of the scalar and pseudo-scalar mesons, has been termed as the quark-meson model with the vacuum term(QMVT).However,this prescription becomes inconsistent when we notice that the curvature mass is akin to defining the meson mass by the self-energy evaluation at vanishing momentum.In this work,we apply the recently reported exact prescription of the on-shell parameter fixing,to that version of quark-meson (QM) model where the two quark flavors are coupled to the eight mesons of the $SU(2{)}_L\times SU(2{)}_R$ linear sigma model with iso-singlet $\sigma$ ($\eta$),iso-triplet $\overrightarrow{a_0}$ ($\vec{\pi }$) scalar(pseudo-scalar) mesons.The model then becomes, the renormalized quark-meson (RQM) model where physical (pole) masses of mesons and pion decay constant, are put into the relation of the running mass parameter and couplings by using the on-shell and the minimal subtraction renormalization schemes.The vacuum effective potential plots,the phase diagrams and the order parameter temperature variations for both the RQM model and QMVT model,are exactly identical for the $m_{\sigma }=$616 MeV.The effective potential is deepest in the QMVT model for $m_{\sigma }<$ 616 MeV and it becomes deepest in the RQM model when $m_{\sigma }>$616 MeV.

    hep-phPRD(2022)·12 citations
15. 15*

    Near or Far Detectors? Optimizing Long-Lived Particle Searches at Electron-Positron Colliders

    Ruth Schäfer🇩🇪 · Finn Tillinger🇩🇪 · Susanne Westhoff🇩🇪

    We explore the discovery potential for long-lived particles at the 250-GeV ILC. The goal is to investigate possible gains of a dedicated far detector over the main detector ILD. For concreteness, we perform our study for sub-GeV axion-like particles $a$ produced via $e^{+}{e}^{-}\to a\gamma$ or $e^{+}{e}^{-}\to Z\gamma \to (a\gamma )\gamma$ and decaying into pairs of charged leptons. In the ideal case of zero background and perfect detection efficiency, we find that far detectors placed in the planned underground cavities or a large cuboid on the ground can enhance the sensitivity to long-lived pseudo-scalars at best moderately. On the other hand, the ILD itself is a perfect environment to search for long-lived particles, due to its excellent angular coverage and radial thickness. For long-lived particles produced with cross sections of a few picobarns, the ILD could probe lifetimes up to 300ns, or proper decay lengths up to 100m, in 250fb${}^{-1}$ of data. For axion-like particles produced through weak interactions, the ILC can reach an even higher sensitivity than searches for displaced vertices in meson decays at Belle II. Our findings apply similarly to other proposed electron-positron experiments with a high angular coverage, such as the FCC-ee and CEPC.

    hep-phhep-exPRD(2023)·34 citations
16. 16*

    Dark Matter Direct Detection in Materials with Spin-Orbit Coupling

    Hsiao-Yi Chen🇺🇸 · Andrea Mitridate🇺🇸 · Tanner Trickle🇺🇸 · Zhengkang Zhang🇺🇸 · Marco Bernardi🇺🇸 · Kathryn M. Zurek🇺🇸

    Semiconductors with $\mathcal{O}(\text{meV})$ band gaps have been shown to be promising targets to search for sub-MeV mass dark matter (DM). In this paper we focus on a class of materials where such narrow band gaps arise naturally as a consequence of spin-orbit coupling (SOC). Specifically, we are interested in computing DM-electron scattering and absorption rates in these materials using state-of-the-art density functional theory (DFT) techniques. To do this, we extend the DM interaction rate calculation to include SOC effects which necessitates a generalization to spin-dependent wave functions. We apply our new formalism to calculate limits for several DM benchmark models using an example ZrTe${}_5$ target and show that the inclusion of SOC can substantially alter projected constraints.

    hep-phcond-mat.mtrl-sciPRD(2022)·34 citations
17. 17*

    Wilson loops in the Hamiltonian formalism

    Robert D. Pisarski🇺🇸

    In a gauge theory, the gauge invariant Hilbert space is unchanged by the coupling to arbitrary local operators. In the presence of Wilson loops, though, the physical Hilbert space must be enlarged by adding test electric charges along the loop. I discuss how at nonzero temperature Polyakov loops are naturally related to the propagator of a test charge. 't Hooft loops represent the propagation of a test magnetic charge, and so do not alter the physical Hilbert space.

    ↳ hep-thhep-lathep-phquant-phPRD(2022)·5 citations
18. 18*

    On Gauge Consistency In Gauge-Fixed Yang-Mills Theory

    Jan M. Pawlowski🇩🇪 · Coralie S. Schneider🇩🇪 · Nicolas Wink🇩🇪

    We investigate BRST invariance in Landau gauge Yang-Mills theory with functional methods. To that end, we solve the coupled system of functional renormalisation group equations for the momentum-dependent ghost and gluon propagator, ghost-gluon, and three- and four-gluon vertex dressings. The equations for both, transverse and longitudinal correlation functions are solved self-consistently: all correlation functions are fed back into the loops. Additionally, we also use the Slavnov-Taylor identities for computing the longitudinal correlation functions on the basis of the above results. Then, the gauge consistency of the solutions is checked by comparing the respective longitudinal correlation functions. We find good agreement of these results, hinting at the gauge consistency of our setup.

    ↳ hep-thhep-lathep-ph21 citations
19. 19*

    Impact of hadronic interactions and conservation laws on cumulants of conserved charges in a dynamical model

    Jan Hammelmann🇩🇪 · Hannah Elfner🇩🇪

    Understanding the phase diagram of QCD by measuring fluctuations of conserved charges in heavy-ion collision is one of the main goals of the beam energy scan program at RHIC. Within this work, we calculate the role of hadronic interactions and momentum cuts on cumulants of conserved charges up to fourth order in a system in equilibrium within a hadronic transport approach (SMASH). In our model the net baryon, net charge and net strangeness is perfectly conserved on an event-by-event basis and the cumulants are calculated as a function of subvolume sizes and compared to analytic expectations. We find a modification of the kurtosis due to charge annihilation processes in systems with simplified degrees of freedom. Furthermore the result of the full SMASH hadron gas for the net baryon and net proton number fluctuations is presented for systems with zero and finite values of baryon chemical potential. Additionally we find that due to dynamical correlations the cumulants of the net baryon number cannot easily be recovered from the net protons. Finally the influence of deuteron cluster formation on the net proton and net baryon fluctuations in a simplified system is shown. This analysis is important to better understand the relation between measurements of fluctuations in heavy-ion collisions and theoretical calculation which are often performed in a grand canonical ensemble.

    ↳ nucl-thhep-phPRC(2023)·13 citations
20. 20*

    2021 Update on ${\epsilon }_K$ with lattice QCD inputs

    Jeehun Kim🇰🇷 · Yong-Chull Jang🇺🇸 · Sunkyu Lee · Weonjong Lee · Jaehoon Leem🇰🇷 · Chanju Park · Sungwoo Park (SWME Collaboration)

    We present recent updates for ${\epsilon }_K$ determined directly from the standard model (SM) with lattice QCD inputs such as ${\hat{B}}_K$, $|V_{cb}|$, $|V_{us}|$, ${\xi }_0$, ${\xi }_2$, ${\xi }_{\text{LD}}$, $f_K$, and $m_c$. We find that the standard model with exclusive $|V_{cb}|$ and other lattice QCD inputs describes only 66\% of the experimental value of $|{\epsilon }_K|$ and does not explain its remaining 34\%, which leads to a strong tension in $|{\epsilon }_K|$ at the $4.5\sigma \sim 3.7\sigma$ level between the SM theory and experiment. We also find that this tension disappears when we use the inclusive value of $|V_{cb}|$ obtained using the heavy quark expansion based on the QCD sum rule approach.

    ↳ hep-lathep-phPoS(2021)·7 citations
21. 21*

    Photon-ALP oscillations inducing modifications to photon polarization

    Giorgio Galanti🇮🇹

    Axion-like particles (ALPs) are very light, neutral, spin zero bosons predicted by many theories which try to complete the standard model of elementary particles. ALPs interact primarily with two photons and can generate photon-ALP oscillations in the presence of an external magnetic field. They are attracting increasing interest since photon-ALP oscillations produce deep consequences in very-high-energy (VHE) astrophysics. Two hints for the existence of an ALP have recently been proposed. In this paper, we study another effect of the photon-ALP interaction: the change of the polarization state of photons. In particular, we study the propagation of the photon-ALP beam starting where photons are produced - we consider photons generated in a galaxy cluster or in the jet of a blazar - crossing several magnetized media (blazar jet, host galaxy, galaxy cluster, extragalactic space, Milky Way) up to their arrival at the Earth. In the presence of photon-ALP interaction, we analyze the final photon survival probability $P_{\gamma \to \gamma }$ and the corresponding photon degree of linear polarization ${\Pi }_L$ for energies in the range $(1-10^{15})\mathrm{eV}$. We observe that photons, which are expected as unpolarized in the absence of ALPs, are made partially polarized by photon-ALP interaction. Our findings can be tested by observatories like IXPE (already operative), and by the proposed missions eXTP, XL-Calibur, NGXP and XPP in the X-ray band and by COSI (approved to launch), e-ASTROGAM and AMEGO in the high-energy range. We also discover a peculiar feature in the VHE band, where photons at energies above $\sim (1-10)\mathrm{TeV}$ are fully polarized because of photon-ALP interaction. A possible detection of this feature would represent a proof for the existence of an ALP, but, unfortunately, current technologies do not allow yet to detect photon polarization up to so high energies.

    ↳ astro-ph.HEhep-phPRD(2023)·26 citations
22. 22*

    Skewing the CMB$\times$LSS: a Fast Method for Bispectrum Analysis

    Priyesh Chakraborty🇺🇸 · Shu-Fan Chen🇺🇸 · Cora Dvorkin🇺🇸

    Upcoming cosmic microwave background (CMB) lensing measurements and tomographic galaxy surveys are expected to provide us with high-precision data sets in the coming years, thus paving the way for fruitful cross-correlation analyses. In this paper we study the information content of the weighted skew-spectrum, a nearly-optimal estimator of the angular bispectrum amplitude, as a means to extract non-Gaussian information on both bias and cosmological parameters from the bispectra of galaxies cross-correlated with CMB lensing, while gaining significantly on speed. Our results show that for the combination of the Planck satellite and the Dark Energy Spectroscopic Instrument (DESI), the difference in the constraints on bias and cosmological parameters from the skew-spectrum and the bispectrum is at most $17\%$. We further compare and find agreement between our theoretical skew-spectra and those estimated from N-body simulations, for which it is important to include gravitational non-linearities beyond perturbation theory and the post-Born effect for CMB lensing. We define an algorithm to apply the skew-spectrum estimator to the data and, as a preliminary step, we use the skew-spectra to constrain bias parameters and the amplitude of shot noise from the simulations through a Markov chain Monte Carlo likelihood analysis, finding that it may be possible to reach percent-level estimates for the linear bias parameter $b_1$.

    ↳ astro-ph.COhep-phJCAP(2022)·15 citations
23. 23*

    Completely Quantum Neural Networks

    Steve Abel🇬🇧 · Juan C. Criado🇬🇧 · Michael Spannowsky🇬🇧

    Artificial neural networks are at the heart of modern deep learning algorithms. We describe how to embed and train a general neural network in a quantum annealer without introducing any classical element in training. To implement the network on a state-of-the-art quantum annealer, we develop three crucial ingredients: binary encoding the free parameters of the network, polynomial approximation of the activation function, and reduction of binary higher-order polynomials into quadratic ones. Together, these ideas allow encoding the loss function as an Ising model Hamiltonian. The quantum annealer then trains the network by finding the ground state. We implement this for an elementary network and illustrate the advantages of quantum training: its consistency in finding the global minimum of the loss function and the fact that the network training converges in a single annealing step, which leads to short training times while maintaining a high classification performance. Our approach opens a novel avenue for the quantum training of general machine learning models.

    ↳ quant-phcs.LGhep-phhep-thPRA(2022)·43 citations
24. 24*

    Negative Newton constant may destroy some conjectures

    G.E. Volovik🇫🇮

    The magnitude and sign of the gravitational coupling $1/G$ depend on the relations between different contributions from scalar, fermionic and vector fields. In principle, this may give the zero and negative values of $1/G$ in some hypothetical Universes with the proper relations between the fermionic and bosonic species. We consider different conjectures related to gravity, such as the wave function collapse caused by gravity, entropic gravity, and maximum force. We find that some of them do not work in the Universes with zero or negative $1/G$, and thus cannot be considered as universal. Thus the extension of the gravitational coupling to $1/G\le 0$ provides the test on the universality of the proposed theories of gravity.

    ↳ gr-qccond-mat.otherhep-phMod.Phys.Lett.A(2022)·5 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.