Wed·Feb 3, 2021Wednesday·February 3, 2021

1. 01*

   Deuterium scattering experiments in CTEQ global QCD analyses: a comparative investigation

   A. Accardi🇺🇸 · T. J. Hobbs🇺🇸 · X. Jing🇺🇸 · P. M. Nadolsky🇺🇸

   Experimental measurements in deep-inelastic scattering and lepton-pair production on deuterium targets play an important role in the flavor separation of $u$ and $d$ (anti)quarks in global QCD analyses of the parton distribution functions (PDFs) of the nucleon. We investigate the impact of theoretical corrections accounting for the light-nuclear structure of the deuteron upon the fitted $u,d$-quark, gluon, and other PDFs in the CJ15 and CT18 families of next-to-leading order CTEQ global analyses. The investigation is done using the $L_2$ sensitivity statistical method, which provides a common metric to quantify the strength of experimental constraints on various PDFs and ratios of PDFs in the two distinct fitting frameworks. Using the $L_2$ sensitivity and other approaches, we examine the compatibility of deuteron data sets with other fitted experiments under varied implementations of the deuteron corrections. We find that freely-fitted deuteron corrections modify the PDF uncertainty at large momentum fractions and will be relevant for future PDFs affecting electroweak precision measurements.

   hep-phhep-exnucl-exnucl-thEPJC(2021)·31 citations
2. 02*

   Constraining CP violating operators in charged and neutral triple gauge couplings

   Anke Biekötter🇬🇧 · Parisa Gregg🇬🇧 · Frank Krauss🇬🇧 · Marek Schönherr🇬🇧

   We constrain $CP$-violating charged and neutral anomalous triple gauge couplings using LHC measurements and projections of diboson and VBF $Vjj$ production, both with subsequent leptonic decays. For triple gauge couplings involving $W$ bosons we analyse asymmetries and interpret our results in the SMEFT at dimension-six. For neutral triple gauge couplings, which are dominantly constrained by high transverse-momentum bins, we present the resulting bounds in terms of a general anomalous couplings framework.

   hep-phPLB(2021)·28 citations
3. 03*

   A Standard Model Explanation for the "ATOMKI Anomaly"

   A. Aleksejevs🇨🇦 · S. Barkanova🇨🇦 · Yu.G. Kolomensky🇺🇸 · B. Sheff🇺🇸

   Using the $e^{+}{e}^{-}$ pair spectrometer at the 5 MV Van de Graaff accelerator at the Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI), Krasznahorkay et al. have claimed a 6.8$\sigma$ excess at high $e^{+}{e}^{-}$ opening angles in the internal pair creation isoscalar transition ${}^8\mathrm{Be}(18.15)\to {}^8\mathrm{Be}{e}^{+}{e}^{-}$. A hypothetical gauge boson with the mass circa $17$ MeV, "X17", has been proposed as an explanation for the excess. We show that the observed experimental structure can be reproduced within the Standard Model by adding the full set of second-order corrections and the interference terms to the Born-level decay amplitudes considered by Krasznahorkay et al. We implement a detailed model of the ATOMKI detector, and also show how experimental selection and acceptance bias exacerbate the apparent difference between the experimental data and the Born-level prediction.

   hep-phnucl-exnucl-th36 citations
4. 04*

   Fresh extraction of the proton charge radius from electron scattering

   Zhu-Fang Cui🇨🇳 · Daniele Binosi🇮🇹 · Craig D. Roberts🇨🇳 · Sebastian M. Schmidt🇩🇪

   We present a novel method for extracting the proton radius from elastic electron-proton ($ep$) scattering data. The approach is based on interpolation via continued fractions augmented by statistical sampling and avoids any assumptions on the form of function used for the representation of data and subsequent extrapolation onto $Q^2\simeq 0$. Applying the method to extant modern $ep$ data sets, we find that all results are mutually consistent and, combining them, arrive at $r_p=0.847(8)$fm. This result compares favourably with values obtained from contemporary measurements of the Lamb shift in muonic hydrogen, transitions in electronic hydrogen, and muonic deuterium spectroscopy.

   hep-phhep-exhep-latnucl-ex+1PRL(2021)·41 citations
5. 05*

   Vector currents of integer-spin Majorana particles

   Seong Youl Choi🇰🇷 · Jae Hoon Jeong🇰🇷

   A general and comprehensive analysis for the vector currents of two massive particles, $X_2$ and $X_1$, with arbitrary integer-spin values is given. Our special focus is on the case when two particles are charge self-conjugate, i.e. Majorana bosons. The general structure of their couplings to an on-shell or off-shell vector boson $V$ is described in a manifestly covariant way and then the constraints on the triple vertex due to discrete CP symmetry and the Majorana condition of two particles being Majorana are worked out. The validity of our full analytic investigation is checked by studying the two-body decay, $X_2\to V{X}_1$, with an on-shell or off-shell $V$ boson in the helicity formalism complementary to the covariant formulation. Threshold effects of the two-lepton invariant-mass and polar-angle correlations in the two sequential two-body decays, $X_2\to V{X}_1$ and $V\to {\ell }^{-}{\ell }^{+}$ with $\ell =e$ or $\mu$, are derived analytically in a compact form by use of the Wick helicity rotation and they are investigated numerically in a few specific spin-combination scenarios for probing the spin and dynamical structure of the $X_2{X}_{1}V$ vertex.

   hep-ph2 citations
6. 06*

   Axion Quality from Superconformal Dynamics

   Yuichiro Nakai🇨🇳 · Motoo Suzuki🇨🇳

   We discuss a possibility that a superconformal dynamics induces the emergence of a global $U(1{)}_{\mathrm{PQ}}$ symmetry to solve the strong CP problem through the axion. Fields spontaneously breaking the $U(1{)}_{\mathrm{PQ}}$ symmetry couple to new quarks charged under the ordinary color $SU(3{)}_C$ and a new $SU(N)$ gauge group. The theory flows into an IR fixed point where the $U(1{)}_{\mathrm{PQ}}$ breaking fields hold a large anomalous dimension leading to the suppression of $U(1{)}_{\mathrm{PQ}}$-violating higher dimensional operators. The spontaneous breaking of the $U(1{)}_{\mathrm{PQ}}$ makes the new quarks massive. The $U(1{)}_{\mathrm{PQ}}$ symmetry is anomalous under the $SU(3{)}_C$ but not under the $SU(N)$ so that the axion couples to only the color $SU(3{)}_C$ and the usual axion potential is generated. We also comment on a model that the $U(1{)}_{\mathrm{PQ}}$ breaking fields are realized as meson superfields in a new supersymmetric QCD.

   hep-phhep-thPLB(2021)·36 citations
7. 07*

   QMeS-Derivation: Mathematica package for the symbolic derivation of functional equations

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

   We present the Mathematica package QMeS-Derivation. It derives symbolic functional equations from a given master equation. The latter include functional renormalisation group equations, Dyson-Schwinger equations, Slavnov-Taylor and Ward identities and their modifications in the presence of momentum cutoffs. The modules allow to derive the functional equations, take functional derivatives, trace over field space, apply a given truncation scheme, and do momentum routings while keeping track of prefactors and signs that arise from fermionic commutation relations. The package furthermore contains an installer as well as Mathematica notebooks with showcase examples.

   hep-phhep-thphysics.comp-phComput.Phys.Commun.(2023)·21 citations
8. 08*

   Search for axion-like dark matter with spin-based amplifiers

   Min Jiang🇨🇳 · Haowen Su🇺🇸 · Antoine Garcon🇩🇪 · Xinhua Peng🇨🇳 · Dmitry Budker🇩🇪

   Ultralight axion-like particles (ALPs) are well-motivated dark matter candidates introduced by theories beyond the standard model. However, the constraints on the existence of ALPs through existing laboratory experiments are hindered by their current sensitivities, which are usually weaker than astrophysical limits. Here, we demonstrate a new quantum sensor to search for ALPs in the mass range that spans about two decades from 8.3 feV to 744 feV. Our sensor makes use of hyperpolarized long-lived nuclear spins as a pre-amplifier that effectively enhances coherently oscillating axion-like dark-matter field by a factor of >100. Using spin-based amplifiers, we achieve an ultrahigh magnetic sensitivity of 18 fT/Hz${}^{1/2}$, which is significantly better than state-of-the-art nuclear-spin magnetometers. Our experiment constrains the parameter space describing the coupling of ALPs to nucleons over our mass range, at 67.5 feV reaching $2.9\times 10^{-9}{\text{GeV}}^{-1}$ ($95\%$ confidence level), improving over previous laboratory limits by at least five orders of magnitude. Our measurements also constrain the ALP-nucleon quadratic interaction and dark photon-nucleon interaction with new limits beyond the astrophysical ones

   hep-phphysics.atom-phquant-phNat.Phys.(2021)·119 citations
9. 09*

   Phenomenological Consequences of Supersymmetric Theories from Dimensional Reduction and Reduction of Couplings

   Gregory Patellis🇬🇷

   The reduction of couplings idea consists in the search for renormalization group invariant relations between seemingly independent parameters of a theory that hold to all orders of perturbation theory. This concept can be applied to $N=1$ GUTs and make them all-loop finite. In the first part of this thesis, after a review of the reduction of couplings method and the properties of finiteness, four models are analysed: a reduced version of the minimal $N=1$ $SU(5)$, a finite $N=1$ $SU(5)$, a two-loop finite $N=1$ $SU(3{)}^3$ and a reduced version of the MSSM. An update in the phenomenological evaluation is the improved light Higgs-boson mass prediction as provided by the FeynHiggs code. The first three models predict heavy SUSY spectra (produced using the FeynHiggs and SPheno codes) that start just above the TeV scale, consistent with the non-observation LHC results, while the reduced MSSM results in a pseudoscalar Higgs boson mass $M_A$ that is ruled out by recent results of the ATLAS experiment. The three models have very dim prospects of discovery at the HL-LHC. The FCC-hh, however, could be able to test large parts of their predicted spectra. In the second part of the thesis, after a review of the Coset Space Dimensional Reduction, an extension of the SM is presented that results from the dimensional reduction of the $N=1$, $10D$ $E_8$ group over a $M_4\times B_0/{\mathbf{Z}}_3$ space, where $B_0$ is the nearly-Kähler manifold $SU(3)/U(1)\times U(1)$ and ${\mathbf{Z}}_3$ is a discrete group on $B_0$. Using the Wilson breaking mechanism we get a $4D$ $N=1$ $SU(3{)}^3$ model plus two global $U(1)$s. Below the GUT scale we have a two Higgs doublet model in a split-like SUSY version of the SM which is phenomenologically consistent, since it produces masses of the top, bottom and light Higgs particles within the experimental limits and predicts the LSP $\sim 1500GeV$.

   hep-phhep-th9 citations
10. 10*

    Fermion and meson mass generation in non-Hermitian Nambu--Jona-Lasinio models

    Alexander Felski🇩🇪 · S. P. Klevansky🇩🇪

    We investigate the effects of non-Hermiticity on interacting fermionic systems. We do this by including non-Hermitian bilinear terms into the 3+1 dimensional Nambu--Jona-Lasinio (NJL) model. Two possible bilinear modifications give rise to $\mathcal{P}\mathcal{T}$ symmetric theories; this happens when the standard NJL model is extended either by a pseudovector background field $ig\bar{\psi }{\gamma }_5{B}_{\mu }{\gamma }^{\mu }\psi$ or by an antisymmetric-tensor background field $g\bar{\psi }{F}_{\mu \nu }{\gamma }^{\mu }{\gamma }^{\nu }\psi$. The three remaining bilinears are {\it anti}-$\mathcal{P}\mathcal{T}$-symmetric in nature, $ig\bar{\psi }{B}_{\mu }{\gamma }^{\mu }\psi ,ig\bar{\psi }{\gamma }_5\psi$ and $ig\bar{\psi }1\psi$, so that the Hamiltonian then has no overall symmetry. The pseudovector $ig\bar{\psi }{\gamma }_5{B}_{\mu }{\gamma }^{\mu }\psi$ and the vector $ig\bar{\psi }{B}_{\mu }{\gamma }^{\mu }\psi$ combinations, are, in addition, chirally symmetric. Thus, within this framework we are able to examine the effects that the various combinations of non-Hermiticity, $\mathcal{P}\mathcal{T}$ symmetry, chiral symmetry and the two-body interactions of the NJL model have on the existence and dynamical generation of a real effective fermion mass (a feature which is absent in the corresponding modified massless free Dirac models) as well as on the masses of the composite particles, the pseudoscalar and scalar mesonic modes ($\pi$ and $\sigma$ mesons). Our findings demonstrate that $\mathcal{P}\mathcal{T}$ symmetry is not necessary for real fermion mass solutions to exist, rather the two-body interactions of the NJL model supersede the non-Hermitian bilinear effects. The effects of chiral symmetry are evident most clearly in the meson modes, the pseudoscalar of which will always be Goldstone in nature if the system is chirally symmetric. Second solutions of the mesonic equations are also discussed.

    hep-phhep-thmath-phmath.MP+1PRD(2021)·9 citations
11. 11*

    Determination of collinear and TMD photon densities using the Parton Branching method

    H. Jung🇩🇪 · S. Taheri Monfared🇩🇪 · T. Wening🇩🇪

    We present the first determination of transverse momentum dependent (TMD) photon densities with the Parton Branching method. The photon distribution is generated perturbatively without intrinsic photon component. The input parameters for quarks and gluons are determined from fits to precision measurements of deep inelastic scattering cross sections at HERA. The TMD densities are used to predict the mass and transverse momentum spectra of very high mass lepton pairs from both Drell-Yan production and Photon-Initiated lepton processes at the LHC.

    hep-phPLB(2021)·19 citations
12. 12*

    Photon-jet events as a probe of axion-like particles at the LHC

    Daohan Wang🇨🇳 · Lei Wu🇨🇳 · Jin Min Yang🇨🇳 · Mengchao Zhang🇨🇳

    Axion-like particles (ALPs) are predicted by many extensions of the Standard Model (SM). When ALP mass lies in the range of MeV to GeV, the cosmology and astrophysics will be largely irrelevant. In this work, we investigate such light ALPs through the ALP-strahlung process $pp\to Va(\to \gamma \gamma )$ at the 14 TeV LHC with an integrated luminosity of 3000 fb${}^{-1}$ (HL-LHC). With the photon-jet algorithm, we demonstrate that our approach can probe the mass range of ALPs, which is inaccessible to previous LHC experiments. The obtained result can surpass the existing limits on ALP-photon coupling in the ALP mass range from 0.3 GeV to 10 GeV.

    hep-phhep-exPRD(2021)·50 citations
13. 13*

    Non-leptonic two-body decays of ${\Lambda }_b^0$ in light-front quark model

    C.Q. Geng🇨🇳 · Chia-Wei Liu🇹🇼 · Tien-Hsueh Tsai🇹🇼

    We study the non-leptonic two-body weak decays of ${\Lambda }_b^0\to pM$ with $M=({\pi }^{-},K^{-})$ and $({\rho }^{-},K^{\ast -})$ in the light-front quark model under the generalized factorization ansatz. By considering the Fermi statistic between quarks and determining spin-flavor structures in baryons, we calculate the branching ratios ($\mathcal{B}$s) and CP-violating rate asymmetries (${\mathcal{A}}_{CP}$s) in the decays. Explicitly, we find that $\mathcal{B}({\Lambda }_b^0\to p{\pi }^{-},p{K}^{-})=(4.18\pm 0.15\pm 0.30,5.76\pm 0.88\pm 0.23)\times 10^{-6}$ and ${\mathcal{A}}_{CP}({\Lambda }_b^0\to p{\pi }^{-},p{K}^{-})=(-3.60\pm 0.14\pm 0.14,6.36\pm 0.21\pm 0.18)\%$ in comparison with the data of $\mathcal{B}({\Lambda }_b^0\to p{\pi }^{-},p{K}^{-})=(4.5\pm 0.8,5.4\pm 1.0)\times 10^{-6}$ and ${\mathcal{A}}_{CP}({\Lambda }_b^0\to p{\pi }^{-},p{K}^{-})=(-2.5\pm 2.9,-2.5\pm 2.2)\%$ given by the Particle Data Group, respectively. We also predict that $\mathcal{B}({\Lambda }_b^0\to p{\rho }^{-},p{K}^{\ast -})=(12.13\pm 3.27\pm 0.91,2.58\pm 0.87\pm 0.13)\times 10^{-6}$ and ${\mathcal{A}}_{CP}({\Lambda }_b^0\to p{\rho }^{-},p{K}^{\ast -})=(-3.32\pm 0.00\pm 0.14,19.25\pm 0.00\pm 0.80)\%$, which could be observed by the experiments at LHCb.

    hep-phhep-exPLB(2021)·15 citations
14. 14*

    Sensitivity of accelerator-based neutrino experiments to neutrino-electron scattering radiative corrections

    Omar G. Miranda🇲🇽 · Guadalupe Moreno-Granados🇲🇽 · Celio A. Moura🇧🇷

    Future long-baseline neutrino experiments will measure neutrino oscillation properties with unprecedented precision and will search for clear signatures of CP violation in the leptonic sector. Near detectors can measure the neutrino-electron scattering with high statistics, giving the chance for its precise measurement. We study, in this work, the expectations for the measurement of radiative corrections in this process. We focus on the determination of contributions that are exclusive to the neutrino channels, particularly on the neutrino charge radius. We illustrate how the perspectives in a first clear measurement of this effective quantity are encouraging.

    hep-phPRD(2021)·8 citations
15. 15*

    On the Application of Intersection Theory to Feynman Integrals: The Univariate Case

    Hjalte Frellesvig🇩🇰 · Luca Mattiazzi🇮🇹

    This document is a contribution to the proceedings of the MathemAmplitudes 2019 conference held in December 2019 in Padova, Italy. A key step in modern high energy physics scattering amplitudes computation is to express the latter in terms of a minimal set of Feynman integrals using linear relations. In this work we present an innovative approach based on intersection theory, in order to achieve this decomposition. This allows for the direct computation of the reduction, projecting integrals appearing in the scattering amplitudes onto an integral basis in the same fashion as vectors may be projected onto a vector basis. Specifically, we will derive and discuss few identities between maximally cut Feynman integrals, showing their direct decomposition. This contribution will focus on the univariate part of the story, with the multivariate generalisation being discussed in a different contribution by Gasparotto and Mandal.

    hep-phhep-thPoS(2022)·18 citations
16. 16*

    Phase transition gravitational waves from pseudo-Nambu-Goldstone dark matter and two Higgs doublets

    Zhao Zhang🇨🇳 · Chengfeng Cai🇨🇳 · Xue-Min Jiang🇨🇳 · Yi-Lei Tang🇨🇳 · Zhao-Huan Yu🇨🇳 · Hong-Hao Zhang🇨🇳

    We investigate the potential stochastic gravitational waves from first-order electroweak phase transitions in a model with pseudo-Nambu-Goldstone dark matter and two Higgs doublets. The dark matter candidate can naturally evade direct detection bounds, and can achieve the observed relic abundance via the thermal mechanism. Three scalar fields in the model obtain vacuum expectation values, related to phase transitions at the early Universe. We search for the parameter points that can cause first-order phase transitions, taking into account the existed experimental constraints. The resulting gravitational wave spectra are further evaluated. Some parameter points are found to induce strong gravitational wave signals, which have the opportunity to be detected in future space-based interferometer experiments LISA, Taiji, and TianQin.

    hep-phastro-ph.COgr-qcJHEP(2021)·40 citations
17. 17*

    First Saturation Correction in High Energy Proton-Nucleus Collisions: I. Time evolution of classical Yang-Mills fields beyond leading order

    Ming Li🇺🇸 · Vladimir V. Skokov🇺🇸

    In high energy proton-nucleus collisions, the single- and double-inclusive soft gluon productions at the leading order have been calculated and phenomenologically studied in various approaches for many years. These studies do not take into account the saturation and multiple rescatterings in the field of the proton. The first saturation correction to these leading order results (the terms that are enhanced by the combination ${\alpha }_s^2{\mu }^2$, where ${\mu }^2$ is the proton's color charge squared per unit transverse area) has not been completely derived despite recent attempts using a diagrammatic approach. This paper is the first in a series of papers towards analytically completing the first saturation correction to physical observables in high energy proton-nucleus collisions. Our approach is to analytically solve the classical Yang-Mills equations in the dilute-dense regime using the Color Glass Condensate effective theory and compute physical observables constructed from classical gluon fields. In the current paper, the Yang-Mills equations are solved perturbatively in the field of the dilute object (the proton). Next-to-leading order and next-to-next-to-leading order analytic solutions are explicitly constructed. A systematic way to obtain all higher order analytic solutions is outlined

    hep-phnucl-thJHEP(2021)·16 citations
18. 18*

    Probing the Pomeron spin structure with Coulomb-nuclear interference

    B. Z. Kopeliovich🇨🇱 · M. Krelina🇨🇿 · I. K. Potashnikova🇨🇱

    Polarized pp elastic scattering at small angles in the Coulomb-nuclear interference (CNI) region offers a unique opportunity to study the spin structure of the Pomeron. Electromagnetic effects in elastic amplitude can be equivalently treated either as Coulomb corrections to the hadronic amplitude (Coulomb phase), or as absorption corrections to the Coulomb scattering amplitude. We perform the first calculation of the Coulomb phase for the spin-flip amplitude and found it significantly exceeding the widely used non-flip Coulomb phase. The alternative description in terms of absorption corrections, though equivalent, turned out to be a more adequate approach for the Coulomb corrected spin-flip amplitude. Inspired by the recent high statistics measurements of single-spin asymmetry in the fixed-target HJET experiment at the BNL, we also performed a Regge analysis of data, aiming at disentangling the Pomeron contribution. However, in spite of an exceptional accuracy of the data, they do not allow to single out the Pomeron term, which strongly correlates with the major sub-leading Reggeons. A stable solution can be accessed only by making additional ad hoc assumptions, e.g. assuming the Pomeron to be a simple Regge pole, or fixing some unknown parameters. Otherwise, in addition to the STAR data at $\sqrt{s}=$200 GeV new measurements, say at 100 GeV or 500 GeV, could become decisive.

    hep-phhep-exPLB(2021)·7 citations
19. 19*

    Shocks and quark-meson scatterings at large density

    Eduardo Grossi🇺🇸 · Friederike J. Ihssen🇩🇪 · Jan M. Pawlowski🇩🇪 · Nicolas Wink🇩🇪

    We discuss the phase structure of the two-flavour quark-meson model including quantum, thermal, density and critical fluctuations with the functional renormalisation group. This study combines two technical advances in the literature, that are also chiefly important for the quantitative access of the phase boundary of QCD at large density or baryon chemical potential. Specifically we allow for the formation and propagation of shocks as well as a fully self-consistent computation of the order parameter potential for chiral symmetry breaking.

    hep-phhep-thPRD(2021)·48 citations
20. 20*

    SU(5) unification of two triplet seesaw and leptogenesis with dark matter and vacuum stability

    Mina Ketan Parida (SOA Deemed to be Univ.)🇮🇳 · Riyanka Samantaray (SOA Deemed to be Univ.)🇮🇳

    We investigate unification prospects of two heavy scalar triplet extension of the standard model where, in the absence of any right-handed neutrino (RHN), type-II seesaw accounts for current oscillation data with hierarchical neutrino masses consistent with cosmological bounds and the lighter triplet decay explains baryon asymmetry of the Universe via leptogenesis. We note that the absence of RHNs in the fundamental fermion representations of SU(5) delineates its outstanding position compared to SO(10) (or $E_6$). In addition, SU(5) needs smaller scalar representations ${15}_{H1}\oplus {15}_{H2}$ compared to much larger representations ${126}_{H1}\oplus {126}_{H2}\subset$ SO(10) (or ${351}_{H1}^{\prime }\oplus {351}_{H2}^{\prime }\subset E_6$). We show how precision gauge coupling unification is achieved through SU(5) with the predictions of different sets of two heavy triplet masses which, besides being compatible with type-II seesaw, are also consistent with unflavoured or $\tau -$ flavoured leptogenesis. In addition to an intermediate mass colour octet fermion, completion of precision gauge coupling unification is found to require essentially the presence of the well known weak triplet fermion $\Sigma (3,0,1)$ in its mass range $M_{\Sigma }\simeq \mathcal{O}(500-3000)$ GeV out of which the dominant dark matter (DM) resonance mass $M_{\Sigma }\ge 2.4$ TeV is known to account for the observed cosmological relic density. The deficiency in relic density for lighter $\Sigma$ solutions is compensated by an additional scalar singlet DM. A GUT ansatz is noted to ensure vacuum stability of the SM scalar potential for all types of unification solutions realised in this work. We discuss proton lifetime estimations for $p\to e^{+}{\pi }^0$ compatible with the present Hyper-Kamiokande bound as a function of an unknown mixing parameter in the model.

    hep-phNPB(2021)·2 citations
21. 21*

    Extraction of the proton mass radius from the vector meson photoproductions near thresholds

    Rong Wang🇨🇳 · Wei Kou🇨🇳 · Ya-Ping Xie🇨🇳 · Xurong Chen🇨🇳

    We present an analysis of the proton mass radius by studying the $t$-dependence of the differential cross sections of the vector meson photoproductions near the thresholds. At low energy, the photoproduction of a quarkonium off the proton is connected to the scalar gravitational form factor of the proton, which is sensitive to the proton mass distribution from the QCD trace anomaly. Under an assumption of the scalar form factor of dipole form, the proton mass radius is extracted via the near-threshold photoproduction data of J/$\psi$, $\varphi$ and $\omega$ vector mesons. The average value of the proton mass radius is estimated to be $\sqrt{⟨R_{\mathrm{m}}^2⟩}=0.67\pm 0.03$ fm, with the dipole cutoff $m_{\mathrm{s}}=1.01\pm 0.04$ GeV.

    hep-phPRD(2021)·50 citations
22. 22*

    Combined theoretical study of the $D^{+}\to {\pi }^{+}\eta \eta$ and $D^{+}\to {\pi }^{+}{\pi }^0\eta$ reactions

    Natsumi Ikeno🇯🇵 · Melahat Bayar🇹🇷 · Eulogio Oset🇪🇸

    We study the $D^{+}\to {\pi }^{+}\eta \eta$ and $D^{+}\to {\pi }^{+}{\pi }^0\eta$ reactions, which are single Cabibbo suppressed and can proceed both through internal and external emission. The primary mechanisms at quark level are considered, followed by hadronization to produce three mesons in the $D^{+}$ decay, and after that the final state interaction of these mesons leads to the production of the $a_0(980)$ resonance, seen in the ${\pi }^{+}\eta$, ${\pi }^0\eta$ mass distributions. The theory has three unknown parameters to determine the shape of the distributions and the ratio between the $D^{+}\to {\pi }^{+}\eta \eta$ and $D^{+}\to {\pi }^{+}{\pi }^0\eta$ rates. This ratio restricts much the sets of parameters but there is still much freedom leading to different shapes in the mass distributions. We call for a measurement of these mass distributions that will settle the reaction mechanism, while at the same time provide relevant information on the way that the $a_0(980)$ resonance is produced in the reactions.

    hep-phEPJC(2021)·20 citations
23. 23*

    Pulling the Higgs and Top needles from the jet stack with Feature Extended Supervised Tagging

    J. A. Aguilar-Saavedra🇪🇸

    Jet tagging has become an essential tool for new physics searches at the high-energy frontier. For jets that contain energetic charged leptons we introduce Feature Extended Supervised Tagging (FEST) which, in addition to jet substructure, considers the features of the charged lepton within the jet. With this method we build dedicated taggers to discriminate among boosted $H\to \ell \nu q\bar{q}$, $t\to \ell \nu b$, and QCD jets (with $\ell$ an electron or muon). The taggers have an impressive performance, allowing for overall light jet rejection factors of $10^4-10^5$, for top quark / Higgs boson efficiencies of $0.5$. The taggers are also excellent in the discrimination of Higgs bosons from top quarks and vice versa, for example rejecting top quarks by factors of $100-300$ for Higgs boson efficiencies of $0.5$. We demonstrate the potential of these taggers to improve the sensitivity to new physics by using as example a search for a new $Z^{\prime }$ boson decaying into $ZH$, in the fully-hadronic final state.

    hep-phhep-exEPJC(2021)·9 citations
24. 24*

    Forces within hadrons on the light front

    Adam Freese🇺🇸 · Gerald A. Miller🇺🇸

    In this work, we find the light front densities for momentum and forces, including pressure and shear forces, within hadrons. This is achieved by deriving relativistically correct expressions relating these densities to the gravitational form factors $A(t)$ and $D(t)$ associated with the energy momentum tensor. The derivation begins from the fundamental definition of density in a quantum field theory, namely the expectation value of a local operator within a spatially-localized state. We find that it is necessary to use the light front formalism to define a density that corresponds to internal hadron structure. When using the instant form formalism, it is impossible to remove the spatial extent of the hadron wave function from any density, and -- even within instant form dynamics -- one does not obtain a Breit frame Fourier transform for a properly defined density. Within the front formalism, we derive new expressions for various mechanical properties of hadrons, including the mechanical radius, as well as for stability conditions. The multipole ansatz for the form factors is used as an example to illustrate all of these findings.

    hep-phnucl-exnucl-thPRD(2021)·93 citations
25. 25*

    Neutral Higgs bosons phenomenology in the compact 341 model and confrontations with the LHC results

    Meriem Djouala🇩🇿 · Noureddine Mebarki🇩🇿

    The phenomenology of the neutral scalar bosons in the compact 341 model is discussed. We show that the predictions of this model are fairly good and compatible with the experimental data by calculating the signal strength of $h_1$ for the channels $b\bar{b}$, W$W^{\ast }$, Z$Z^{\ast }$, $\tau \bar{\tau }$ and $\gamma \gamma$. Moreover, we use the branching ratios to search for the heavy neutral scalar bosons $h_2$ and $h_3$ where we take into account the theoretical constraints to precise the allowed ranges for the fundamental parameters of the scalar potential.

    hep-ph1 citation
26. 26*

    A Living Review of Machine Learning for Particle Physics

    Matthew Feickert🇺🇸 · Benjamin Nachman🇺🇸

    Modern machine learning techniques, including deep learning, are rapidly being applied, adapted, and developed for high energy physics. Given the fast pace of this research, we have created a living review with the goal of providing a nearly comprehensive list of citations for those developing and applying these approaches to experimental, phenomenological, or theoretical analyses. As a living document, it will be updated as often as possible to incorporate the latest developments. A list of proper (unchanging) reviews can be found within. Papers are grouped into a small set of topics to be as useful as possible. Suggestions and contributions are most welcome, and we provide instructions for participating.

    hep-phcs.LGhep-exphysics.data-an+1245 citations
27. 27*

    Investigations on hoop conjecture for horizonless spherical charged stars

    Yan Peng🇨🇳

    For horizonless spherical stars with uniform charge density, the hoop conjecture was tested based on the interior solution. In this work, we are interested in more general horizonless spherical charged stars. We test hoop conjecture using the exterior solution since all types of interior solutions correspond to the same exterior Reissner-Nordsr$\ddot{o}$m solution. Our analysis shows that the hoop conjecture is violated for very compact stars if we express the conjecture with the total ADM mass. And the hoop conjecture holds if we express the conjecture using the mass in the sphere.

    ↳ gr-qchep-phhep-thNPB(2021)·2 citations
28. 28*

    Using a multi-messenger and multi-wavelength observational strategy to probe the nature of dark energy through direct measurements of cosmic expansion history

    Jing-Zhao Qi🇨🇳 · Shang-Jie Jin🇨🇳 · Xi-Long Fan🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳

    In the near future, the redshift drift observations in optical and radio bands will provide precise measurements on $H(z)$ covering the redshift ranges of $2<z<5$ and $0<z<0.3$. In addition, gravitational wave (GW) standard siren observations could make measurements on the dipole anisotropy of luminosity distance, which will also provide the $H(z)$ measurements in the redshift range of $0<z<3$. In this work, we propose a multi-messenger and multi-wavelength observational strategy to measure $H(z)$ based on the three next-generation projects, E-ELT, SKA, and DECIGO, and we wish to see whether the future $H(z)$ measurements could provide tight constraints on dark-energy parameters. The dark energy models we consider include $\Lambda$CDM, $w$CDM, CPL, HDE, and I$\Lambda$CDM models. It is found that E-ELT, SKA1, and DECIGO are highly complementary in constraining dark energy models. Although any one of these three data sets can only give rather weak constraints on each model we consider, the combination of them could significantly break the parameter degeneracies and give much tighter constraints on almost all the cosmological parameters. Moreover, we find that the combination of E-ELT, SKA1, DECIGO, and CMB could further improve the constraints on dark energy parameters, e.g., $\sigma (w_0)=0.024$ and $\sigma (w_a)=0.17$ in the CPL model, which means that these three promising probes will play a key role in helping reveal the nature of dark energy.

    ↳ astro-ph.COgr-qchep-phJCAP(2021)·46 citations
29. 29*

    Magnetic field generation from bubble collisions during first-order phase transition

    Jing Yang🇨🇳 · Ligong Bian🇨🇳

    We study the magnetic fields generation from the cosmological first-order electroweak phase transition. We calculate the magnetic field induced by the variation of the Higgs phase for two bubbles and three bubbles collisions. Our study shows that electromagnetic currents in the collision direction produce the ring-like magnetic field in the intersect regions of colliding bubbles, which may seed the primordial magnetic field that are constrained by intergalatic field observations.

    ↳ astro-ph.COhep-phhep-thPRD(2022)·29 citations
30. 30*

    Possible alterations of local gravitational field inside a superconductor

    G. A. Ummarino🇮🇹 · A. Gallerati🇮🇹

    We calculate the possible interaction between a superconductor and the static Earth's gravitational fields, making use of the gravito-Maxwell formalism combined with the time-dependent Ginzburg-Landau theory. We try to estimate which are the most favourable conditions to enhance the effect, optimizing the superconductor parameters characterizing the chosen sample. We also give a qualitative comparison of the behaviour of high-$T_{\text{c}}$ and classical low-$T_{\text{c}}$ superconductors with respect to the gravity/superfluid interplay.

    ↳ gr-qccond-mat.supr-conhep-phhep-thEntropy(2021)·10 citations
31. 31*

    Anomalous gravitomagnetic moment and non-universality of the axial vortical effect at finite temperature

    M. Buzzegoli🇮🇹 · Dmitri E. Kharzeev🇺🇸

    The coupling between the spin of a massive Dirac fermion and the angular momentum of the medium, i.e. the gravitomagnetic moment, is shown here to be renormalized by QED interactions at finite temperature. This means that the anomalous gravitomagnetic moment (AGM) does not vanish, and implies that thermal effects can break the Einstein equivalence principle in quantum field theory, as argued previously. We also show that the AGM causes radiative corrections to the axial current of massive fermions induced by vorticity in quantum relativistic fluids, similarly to the previous findings for massless fermions. The radiative QCD effects on the AGM should significantly affect the production of polarized hadrons in heavy-ion collisions.

    ↳ hep-thhep-phPRD(2021)·14 citations
32. 32*

    Substructure at High Speed I: Inferring the Escape Velocity in the Presence of Kinematic Substructure

    Lina Necib🇺🇸 · Tongyan Lin🇺🇸

    The local escape velocity provides valuable inputs to the mass profile of the Galaxy, and requires understanding the tail of the stellar speed distribution. Following Leonard $\&$ Tremaine (1990), various works have since modeled the tail of the stellar speed distribution as $\propto (v_{\mathrm{esc}}-v{)}^k$, where $v_{\mathrm{esc}}$ is the escape velocity, and $k$ is the slope of the distribution. In such studies, however, these two parameters were found to be largely degenerate and often a narrow prior is imposed on $k$ in order to constrain $v_{\mathrm{esc}}$. Furthermore, the validity of the power law form is likely to break down in the presence of multiple kinematic substructures. In this paper, we introduce a strategy that for the first time takes into account the presence of kinematic substructure. We model the tail of the velocity distribution as a sum of multiple power laws without imposing strong priors. Using mock data, we show the robustness of this method in the presence of kinematic structure that is similar to the recently-discovered Gaia Sausage. In a companion paper, we present the new measurement of the escape velocity and subsequently the mass of the Milky Way using Gaia DR2 data.

    ↳ astro-ph.GAhep-phApJ(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.