Wed·May 6, 2020Wednesday·May 6, 2020

1. 01*

   Sterile Neutrinos and the Global Reactor Antineutrino Dataset

   Jeffrey M. Berryman🇺🇸 · Patrick Huber🇺🇸

   We present results from global fits to the available reactor antineutrino dataset, as of Fall 2019, to determine the global preference for a fourth, sterile neutrino. We have separately considered experiments that measure the integrated inverse-beta decay (IBD) rate from those that measure the energy spectrum of IBD events at one or more locations. The software used is the newly developed GLoBESfit tool set which is based on the publicly available GLoBES framework and will be released as open-source software.

   hep-phhep-exnucl-exnucl-thJHEP(2021)·63 citations
2. 02*

   Gravitational production of vector dark matter

   Aqeel Ahmed🇧🇪 · Bohdan Grzadkowski🇵🇱 · Anna Socha🇵🇱

   A model of vector dark matter that communicates with the Standard Model only through gravitational interactions has been investigated. It has been shown in detail how does the canonical quantization of the vector field in varying FLRW geometry implies a tachyonic enhancement of some of its momentum modes. Approximate solutions of the mode equation have been found and verified against exact numerical ones. De Sitter geometry has been assumed during inflation while after inflation a non-standard cosmological era of reheating with a generic equation of state has been adopted which is followed by the radiation-dominated universe. It has been shown that the spectrum of dark vectors produced gravitationally is centered around a characteristic comoving momentum $k_{\star }$ that is determined in terms of the mass of the vector $m_X$, the Hubble parameter during inflation $H_{\mathrm{I}}$, the equation of state parameter $w$ and the efficiency of reheating $\gamma$. Regions in the parameter space consistent with the observed dark matter relic abundance have been determined, justifying the gravitational production as a viable mechanism for vector dark matter. The results obtained in this paper are applicable within various possible models of inflation/reheating with non-standard cosmology parametrized effectively by the corresponding equation of state and efficiency of reheating.

   hep-phastro-ph.HEJHEP(2020)·174 citations
3. 03*

   Identifying Heavy-Flavor Jets Using Vectors of Locally Aggregated Descriptors

   Jana Bielčíková🇨🇿 · Raghav Kunnawalkam Elayavalli🇺🇸 · Georgy Ponimatkin🇨🇿 · Jörn H. Putschke🇺🇸 · Josef Sivic🇨🇿

   Jets of collimated particles serve a multitude of purposes in high energy collisions. Recently, studies of jet interaction with the quark-gluon plasma (QGP) created in high energy heavy ion collisions are of growing interest, particularly towards understanding partonic energy loss in the QGP medium and its related modifications of the jet shower and fragmentation. Since the QGP is a colored medium, the extent of jet quenching and consequently, the transport properties of the medium are expected to be sensitive to fundamental properties of the jets such as the flavor of the parton that initiates the jet. Identifying the jet flavor enables an extraction of the mass dependence in jet-QGP interactions. We present a novel approach to tagging heavy-flavor jets at collider experiments utilizing the information contained within jet constituents via the \texttt{JetVLAD} model architecture. We show the performance of this model in proton-proton collisions at center of mass energy $\sqrt{s}=200$ GeV as characterized by common metrics and showcase its ability to extract high purity heavy-flavor jet sample at various jet momenta and realistic production cross-sections including a brief discussion on the impact of out-of-time pile-up. Such studies open new opportunities for future high purity heavy-flavor measurements at jet energies accessible at current and future collider experiments.

   hep-phJINST(2021)·9 citations
4. 04*

   Graphic Method for Arbitrary $n$-body Phase Space

   Hao-Jie Jing🇨🇳 · Chao-Wei Shen🇨🇳 · Feng-Kun Guo🇨🇳

   In quantum field theory, the phase space integration is an essential part in all theoretical calculations of cross sections and decay widths. It is also needed for computing the imaginary part of a physical amplitude. A key problem is to get the phase space formula expressed in terms of any chosen invariant masses in an $n$-body system. We propose a graphic method to quickly get the phase space formula of any given invariant masses intuitively for an arbitrary $n$-body system in general $D$-dimensional spacetime, with the involved momenta in any reference frame. The method also greatly simplifies the phase space calculation just as what Feynman diagrams do in calculating scattering amplitudes.

   hep-phhep-exhep-thnucl-ex+1Sci.Bull.(2021)·11 citations
5. 05*

   Searching for Sub-GeV Dark Matter in the Galactic Centre using Hyper-Kamiokande

   Nicole F. Bell🇦🇺 · Matthew J. Dolan🇦🇺 · Sandra Robles🇦🇺

   Indirect detection of dark matter via its annihilation products is a key technique in the search for dark matter in the form of weakly interacting massive particles (WIMPs). Strong constraints exist on the annihilation of WIMPs to highly visible Standard Model final states such as photons or charged particles. In the case of s-wave annihilation, this typically eliminates thermal relic cross sections for dark matter of mass below $\mathcal{O}$(10) GeV. However, such limits typically neglect the possibility that dark matter may annihilate to assumed invisible or hard-to-detect final states, such as neutrinos. This is a difficult paradigm to probe due to the weak neutrino interaction cross section. Considering dark matter annihilation in the Galactic halo, we study the prospects for indirect detection using the Hyper-Kamiokande (HyperK) neutrino experiment, for dark matter of mass below 1 GeV. We undertake a dedicated simulation of the HyperK detector, which we benchmark against results from the similar Super-Kamiokande experiment and HyperK physics projections. We provide projections for the annihilation cross-sections that can be probed by HyperK for annihilation to muon or neutrino final states, and discuss uncertainties associated with the dark matter halo profile. For neutrino final states, we find that HyperK is sensitive to thermal annihilation cross-sections for dark matter with mass around 20 MeV, assuming an NFW halo profile. We also discuss the effects of neutron tagging, and prospects for improving the reach at low mass.

   hep-phastro-ph.COhep-exJCAP(2020)·56 citations
6. 06*

   Informationally complete characters for quark and lepton mixings

   Michel Planat🇫🇷 · Raymond Aschheim🇺🇸 · Marcelo M. Amaral🇺🇸 · Klee Irwin🇺🇸

   A popular account of the mixing patterns for the three generations of quarks and leptons is through the characters $\kappa$ of a finite group $G$. Here we introduce a $d$-dimensional Hilbert space with $d=cc(G)$, the number of conjugacy classes of $G$. Groups under consideration should follow two rules, (a) the character table contains both two- and three-dimensional representations with at least one of them faithful and (b) there are minimal informationally complete measurements under the action of a $d$-dimensional Pauli group over the characters of these representations. Groups with small $d$ that satisfy these rules coincide in a large part with viable ones derived so far for reproducing simultaneously the CKM (quark) and PNMS (lepton) mixing matrices. Groups leading to physical $CP$ violation are singled out.

   hep-phmath.GRmath.RTquant-phSymmetry(2020)·5 citations
7. 07*

   Branching Fractions and CP Asymmetries of the Quasi-Two-Body Decays in $B_s\to K^0({\overline{K}}^0)K^{\pm }{\pi }^{\mp }$ within PQCD Approach

   Zhi-Tian Zou🇨🇳 · Ying Li🇨🇳 · Xin Liu🇨🇳

   Motivated by the first untagged decay-time-integrated amplitude analysis of $B_s\to K_S{K}^{\mp }{\pi }^{\pm }$ decays performed by LHCb collaboration, where the decay amplitudes are modeled to contain the resonant contributions from intermediate resonances $K^{\ast }(892)$, $K_0^{\ast }(1430)$ and $K_2^{\ast }(1430)$, we comprehensively investigate the quasi-two-body $B_s\to K^0/{\overline{K}}^0{K}^{\pm }{\pi }^{\mp }$ decays, and calculate the branching fractions and the time-dependent $CP$ asymmetries within the perturbative QCD approach based on the $k_T$ factorization. In the quasi-two-body space region the calculated branching fractions with the considered intermediate resonances are in good agreement with the experimental results of LHCb by adopting proper $K\pi$ pair wave function, describing the interaction between the kaon and pion in the $K\pi$ pair. Furthermore,within the obtained branching fractions of the quasi-two-body decays, we also calculate the branching fractions of corresponding two-body decays, and the results consist with the LHCb measurements and the earlier studies with errors. For these considered decays, since the final states are not flavour-specific, the time-dependent $CP$ could be measured. We calculate six $CP$-violation observables, which can be tested in the ongoing LHCb experiment.

   hep-phhep-exEPJC(2020)·30 citations
8. 08*

   Asymptotic expansions through the loop-tree duality

   Judith Plenter🇪🇸 · Germán Rodrigo🇪🇸

   First results towards a general method for asymptotic expansions of Feynman amplitudes in the loop-tree duality (LTD) formalism are presented. The asymptotic expansion takes place at integrand-level in the Euclidean space of the loop three-momentum, where the hierarchies among internal and external scales are well-defined. Additionally, the UV behaviour of the individual contributions to the asymptotic expansion emerges only in the first terms of the expansion and is renormalized locally in four space-time dimensions. These two properties represent an advantage over the method of Expansion by Regions (EbR). We explore different approaches in different kinematical limits, and derive general guidelines with several benchmark examples.

   hep-phEPJC(2021)·37 citations
9. 09*

   Comment on the Comment on the paper "Can oscillating neutrino states be formulated universally?''

   Anca Tureanu🇫🇮

   Recently, our work regarding the definition of oscillating neutrino states in Eur. Phys. J. C 80: 68 (2020), arxiv:1902.01232 [hep-ph] has been commented upon in arXiv:2004.04739 [hep-ph]. In this note we show that, contrary to the claim in the comment, our above-mentioned work cannot be reproduced in the scheme of the so-called flavour Fock space approach described in the comment. Moreover, we prove explicitly that a flavour Fock space cannot exist in a model with massive mixed neutrinos. If the flavour Fock space scheme were viable, it would necessarily lead, as a consequence of Coleman's theorem, to the flavour number invariance of the Hamiltonian of mixed neutrino fields, while the Hamiltonian is by construction flavour number violating. Quod est absurdum.

   hep-ph5 citations
10. 10*

    Testing triplet fermions at the electron-positron and electron-proton colliders using fat jet signatures

    Arindam Das🇯🇵 · Sanjoy Mandal🇪🇸 · Tanmoy Modak🇹🇼

    The addition of $SU(2{)}_L$ triplet fermions of zero hypercharge with the Standard Model (SM) helps to explain the origin of the neutrino mass by the so-called seesaw mechanism. Such a scenario is commonly know as the type-III seesaw model. After the electroweak symmetry breaking the mixings between the light and heavy mass eigenstates of the neutral leptons are developed which play important roles in the study of the charged and neutral multiplets of the triplet fermions at the colliders. In this article we study such interactions to produce these multiplets of the triplet fermion at the electron-positron and electron-proton colliders at different center of mass energies. We focus on the heavy triplets, for example, having mass in the TeV scale so that their decay products including the SM the gauge bosons or Higgs boson can be sufficiently boosted, leading to a fat jet. Hence we probe the mixing between light-heavy mass eigenstates of the neutrinos and compare the results with the bounds obtained by the electroweak precision study.

    hep-phhep-exPRD(2020)·34 citations
11. 11*

    Systematic study on the quark-hadron mixed phase in compact stars

    Cheng-Jun Xia🇨🇳 · Toshiki Maruyama🇯🇵 · Nobutoshi Yasutake🇯🇵 · Toshitaka Tatsumi🇯🇵 · Hong Shen🇨🇳 · Hajime Togashi🇯🇵

    We investigate systematically the quark-hadron mixed phase in dense stellar matter, and its influence on compact star structures. The properties of quark matter and hadronic matter are fixed based on various model predictions. Beside adopting constant values, the surface tension $\Sigma$ for the quark-hadron interface is estimated with the multiple reflection expansion method and equivparticle model. To fix the structures of quark-hadron pasta phases, a continuous dimensionality of the structure is adopted as proposed by Ravenhall, Pethick, and Wilson. The corresponding properties of hybrid stars are then obtained and confronted with pulsar observations. It is found that the correlation between radius and tidal deformability in traditional neutron stars preserves in hybrid stars. For those permitted by pulsar observations, in almost all cases the quark phase persists inside the most massive compact stars. The quark-hadron interface plays an important role on hybrid star structures once quark matter emerges. The surface tension $\Sigma$ estimated with various methods increases with density, which predicts stiffer EOSs for the quark-hadron mixed phase and increases the maximum mass of hybrid stars. The EOSs of hybrid star matter are well constrained at densities $n\lesssim 0.8$ fm${}^{-3}$, while larger uncertainty is expected at higher densities.

    hep-phnucl-thPRD(2020)·36 citations
12. 12*

    Transverse-momentum-dependent gluon distribution functions in a spectator model

    Alessandro Bacchetta🇮🇹 · Francesco Giovanni Celiberto🇮🇹 · Marco Radici🇮🇹 · Pieter Taels🇫🇷

    We present a model calculation of transverse-momentum-dependent distributions (TMDs) of gluons in the nucleon. The model is based on the assumption that a nucleon can emit a gluon, and what remains after the emission is treated as a single spectator particle. This spectator particle is considered to be on-shell, but its mass is allowed to take a continuous range of values, described by a spectral function. The nucleon-gluon-spectator coupling is described by an effective vertex containing two form factors. We fix the model parameters to obtain the best agreement with collinear gluon distributions extracted from global fits. We study the tomography in momentum space of gluons inside nucleons for various combinations of their polarizations. These can be used to make predictions of observables relevant for gluon TMD studies at current and future collider facilities.

    hep-phEPJC(2020)·135 citations
13. 13*

    Dark Matter with Light and Ultralight Stückelberg Axions

    Claudio Corianò🇮🇹 · Matteo Maria Maglio🇮🇹 · Alessandro Tatullo🇮🇹 · Dimosthenis Theofilopoulos🇮🇹

    Scenarios with axion-like particles of variable masses, from the milli-eV range to ultralight, can be generated in a natural way in the context of effective field theory models with anomalous $U(1)$ gauge symmetries. They include dimension-5 operators which define a coupling of the axion to the gauge anomaly. They provide a realization, in the domain of ordinary gauge theories, of models for such particles, which evade the usual mass/coupling constraint of ordinary (Peccei-Quinn) axions and are natural dark matter candidates. As an illustration of these models, we present an overview of two of these scenarios. One of them is built around the next-to-minimal MSSM (NMSSM), a model called the USSM-A, which illustrates how the Stückelberg supermultiplet can be used to generate two dark matter candidates, a neutralino containing an axino component coming from the Stückelberg sector, plus the axion ($\text{Im}b$). The real component of the complex Stückelberg field carries dilaton-like ($\text{Re}bFF$) interactions. In a second model, non-supersymmetric, the Stückelberg scale is raised up to the GUT epoch. In this case the axion mass can be ultralight ($\sim 10^{-20}$ eV). The periodic potential generated at the GUT phase transition and the corresponding oscillations are related to a particle whose De Broglie wavelength can be sub-galactic. A similar analysis is also possible for the supersymmetric scenario.

    hep-phPoS(2020)·1 citation
14. 14*

    Model studies of fluctuations in the background for jets in heavy ion collisions

    Charles Hughes🇺🇸 · Antonio Carlos Oliveira Da Silva🇺🇸 · Christine Nattrass🇺🇸

    Jets produced in high energy heavy ion collisions are quenched by the quark gluon plasma. Measurements of these jets are influenced by the methods used to suppress and subtract the large, fluctuating background and the assumptions inherent in these methods. We compare the measurements of the background in Pb+Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV by the ALICE Collaboration $\underline{(B.Abelev\text{et al.},J.HighEnergyPhys.2012,053)}$ to calculations in TennGen (a data-driven random background generator) and PYTHIA Angantyr. A detailed understanding of the width of these fluctuations is important for reducing uncertainties due to unfolding and extending measurements to lower momenta and larger resolution parameters. The standard deviation of the energy in random cones in TennGen is approximately in agreement with the form predicted in the ALICE paper, with deviations of 1--6%. The standard deviation of energy in random cones in Angantyr exceeds the same predictions by approximately 13%. Deviations in both models can be explained by the assumption that the single-particle $d^{2}N/dy$ $d{p}_T$ is a gamma distribution in the derivation of the prediction, whereas the model uses a different distribution. This indicates that model comparisons are potentially sensitive to the treatment of the background. We demonstrate that unfolding methods used to remove background fluctuations from jets can affect the comparisons between models and data, $\text{even in the absence of detector effects}$. Our findings suggest the need to more carefully consider methods for comparing simulations and data.

    hep-phPRC(2022)·5 citations
15. 15*

    Rare decays of the top quark mediated by Z' gauge bosons and flavor violation

    J. I. Aranda🇲🇽 · D. Espinosa-Gomez🇲🇽 · J. Montano🇲🇽 · F. Ramirez-Zavaleta🇲🇽 · E. S. Tututi🇲🇽

    The rare top quark decays mediated by a new neutral massive gauge boson that is predicted in models with extended gauge symmetries are studied. We focus on the processes $t\to cV,uV$ induced at the one loop level, where $V=\gamma ,g$, by considering different extended models. It is found that, within a broad range of mass of the new neutral gauge boson, the models predict branching ratios for the decays in study that are competitive with respect to the corresponding branching ratios in the standard model. In order to establish bound on our branching ratios, we consider the recent experimental bounds as $m_{Z^{\prime }}\ge$ 3.8-4.5 TeV, depending on the model, which also impose restrictions on our calculation. Even in this case, the resulting branching ratios are of the same order of magnitude as that predicted by the standard model. It should be noted that for the case of two models studied here, since no experimental bound exists to compare with, the results could be important, as they are, in the best of cases, two orders of magnitude larger than the predicted by the standard model.

    hep-phMod.Phys.Lett.A(2020)·3 citations
16. 16*

    Observing Left-Right Symmetry in the Cosmic Microwave Background

    Debasish Borah🇮🇳 · Arnab Dasgupta🇰🇷 · Chayan Majumdar🇮🇳 · Dibyendu Nanda🇮🇳

    We consider the possibility of probing left-right symmetric model (LRSM) via cosmic microwave background (CMB). We adopt the minimal LRSM with Higgs doublets, also known as the doublet left-right model (DLRM), where all fermions including the neutrinos acquire masses only via their couplings to the Higgs bidoublet. Due to the Dirac nature of light neutrinos, there exist additional relativistic degrees of freedom which can thermalise in the early universe by virtue of their gauge interactions corresponding to the right sector. We constrain the model from Planck 2018 bound on the effective relativistic degrees of freedom and also estimate the prospects for planned CMB Stage IV experiments to constrain the model further. We find that $W_R$ boson mass below 4.06 TeV can be ruled out from Planck 2018 bound at $2\sigma$ CL in the exact left-right symmetric limit which is equally competitive as the LHC bounds from dijet resonance searches. On the other hand Planck 2018 bound at $1\sigma$ CL can rule out a much larger parameter space out of reach of present direct search experiments, even in the presence of additional relativistic degrees of freedom around the TeV corner. We also study the consequence of these constraints on dark matter in DLRM by considering a right handed real fermion quintuplet to be the dominant dark matter component in the universe.

    hep-phastro-ph.COPRD(2020)·27 citations
17. 17*

    Dark Higgs Dark Matter

    Cristina Mondino🇺🇸 · Maxim Pospelov🇺🇸 · Joshua T. Ruderman🇺🇸 · Oren Slone🇺🇸

    A new $U(1)$ dark gauge group coupled to the Standard Model (SM) via the kinetic mixing portal provides a natural dark matter candidate in the form of the Higgs field, $h_d$, responsible for generating the mass of the dark photon, ${\gamma }_d$. We show that the condition $m_{h_d}\le m_{{\gamma }_d}$, together with smallness of the kinetic mixing parameter, $ϵ$, and/or dark gauge coupling, $g_d$, leads the dark Higgs to be sufficiently metastable to constitute dark matter. We analyze the Universe's thermal history and show that both freeze-in, $\mathrm{SM}\to \{{\gamma }_d,h_d\}$, and freeze-out, $\{{\gamma }_d,h_d\}\to \mathrm{SM}$, processes can lead to viable dark Higgs dark matter with a sub-GeV mass and a kinetic mixing parameter in the range $10^{-13}\lesssim ϵ\lesssim 10^{-6}$. Observable signals in astrophysics and cosmology include modifications to primordial elemental abundances, altered energetics of supernovae explosions, dark Higgs decays in the late Universe, and dark matter self-interactions.

    hep-phastro-ph.COPRD(2021)·31 citations
18. 18*

    Polarized jet fragmentation functions

    Zhong-Bo Kang🇺🇸 · Kyle Lee🇺🇸 · Fanyi Zhao🇺🇸

    We develop the theoretical framework needed to study the distribution of hadrons with general polarization inside jets, with and without transverse momentum measured with respect to the standard jet axis. The key development in this paper, referred to as "polarized jet fragmentation functions", opens up new opportunities to study both collinear and transverse momentum dependent (TMD) fragmentation functions. As two examples of the developed framework, we study longitudinally polarized collinear $\Lambda$ and transversely polarized TMD $\Lambda$ production inside jets in both $pp$ and $ep$ collisions. We find that both observables have high potential in constraining spin-dependent fragmentation functions with sizeable asymmetries predicted, in particular, at the future Electron-Ion Collider.

    hep-phhep-exnucl-exnucl-thPLB(2020)·67 citations
19. 19*

    Merger of Dark Matter Axion Clumps and Resonant Photon Emission

    Mark P. Hertzberg🇺🇸 · Yao Li🇨🇳 · Enrico D. Schiappacasse🇫🇮

    A portion of light scalar dark matter, especially axions, may organize into gravitationally bound clumps (stars) and be present in large number in the galaxy today. It is therefore of utmost interest to determine if there are novel observational signatures of this scenario. Work has shown that for moderately large axion-photon couplings, such clumps can undergo parametric resonance into photons, for clumps above a critical mass $M_c^{\star }$ determined precisely by some of us in Ref. [1]. In order to obtain a clump above the critical mass in the galaxy today would require mergers. In this work we perform full 3-dimensional simulations of pairs of axion clumps and determine the conditions under which mergers take place through the emission of scalar waves, including analyzing head-on and non-head-on collisions, phase dependence, and relative velocities. Consistent with other work in the literature, we find that the final mass from the merger $M_{\text{final}}^{\star }\approx 0.7(M_1^{\star }+M_2^{\star })$ is larger than each of the original clump masses (for $M_1^{\star }\sim M_2^{\star }$). Hence, it is possible for sub-critical mass clumps to merge and become super-critical and therefore undergo parametric resonance into photons. We find that mergers are expected to be kinematically allowed in the galaxy today for high Peccei-Quinn scales, which is strongly suggested by unification ideas, although the collision rate is small. While mergers can happen for axions with lower Peccei-Quinn scales due to statistical fluctuations in relative velocities, as they have a high collision rate. We estimate the collision and merger rates within the Milky Way galaxy today. We find that a merger leads to a flux of energy on earth that can be appreciable and we mention observational search strategies.

    hep-phastro-ph.COastro-ph.HEgr-qc+1JCAP(2020)·75 citations
20. 20*

    Heavy quark diffusion in an overoccupied gluon plasma

    K. Boguslavski🇦🇹 · A. Kurkela🇨🇭 · T. Lappi🇫🇮 · J. Peuron🇮🇹

    We extract the heavy-quark diffusion coefficient \kappa and the resulting momentum broadening <p^2> in a far-from-equilibrium non-Abelian plasma. We find several features in the time dependence of the momentum broadening: a short initial rapid growth of <p^2>, followed by linear growth with time due to Langevin-type dynamics and damped oscillations around this growth at the plasmon frequency. We show that these novel oscillations are not easily explained using perturbative techniques but result from an excess of gluons at low momenta. These oscillation are therefore a gauge invariant confirmation of the infrared enhancement we had previously observed in gauge-fixed correlation functions. We argue that the kinetic theory description of such systems becomes less reliable in the presence of this IR enhancement.

    hep-phhep-latnucl-thJHEP(2020)·65 citations
21. 21*

    Charmonium properties from lattice QCD + QED: hyperfine splitting, $J/\psi$ leptonic width, charm quark mass and $a_{\mu }^c$

    D. Hatton🇬🇧 · C. T. H. Davies🇬🇧 · B. Galloway🇬🇧 · J. Koponen🇯🇵 · G. P. Lepage🇺🇸 · A. T. Lytle🇮🇹

    We have performed the first $n_f=2+1+1$ lattice QCD computations of the properties (masses and decay constants) of ground-state charmonium mesons. Our calculation uses the HISQ action to generate quark-line connected two-point correlation functions on MILC gluon field configurations that include $u/d$ quark masses going down to the physical point, tuning the $c$ quark mass from $M_{J/\psi }$ and including the effect of the $c$ quark's electric charge through quenched QED. We obtain $M_{J/\psi }-M_{{\eta }_c}$ (connected) = 120.3(1.1) MeV and interpret the difference with experiment as the impact on $M_{{\eta }_c}$ of its decay to gluons, missing from the lattice calculation. This allows us to determine $\Delta M_{{\eta }_c}^{\mathrm{annihiln}}$ =+7.3(1.2) MeV, giving its value for the first time. Our result of $f_{J/\psi }=$ 0.4104(17) GeV, gives $\Gamma (J/\psi \to e^{+}{e}^{-})$=5.637(49) keV, in agreement with, but now more accurate than experiment. At the same time we have improved the determination of the $c$ quark mass, including the impact of quenched QED to give ${\overline{m}}_c(3\mathrm{GeV})$ = 0.9841(51) GeV. We have also used the time-moments of the vector charmonium current-current correlators to improve the lattice QCD result for the $c$ quark HVP contribution to the anomalous magnetic moment of the muon. We obtain $a_{\mu }^c=14.638(47)\times 10^{-10}$, which is 2.5$\sigma$ higher than the value derived using moments extracted from some sets of experimental data on $R(e^{+}{e}^{-}\to \mathrm{hadrons})$. This value for $a_{\mu }^c$ includes our determination of the effect of QED on this quantity, $\delta a_{\mu }^c=0.0313(28)\times 10^{-10}$.

    ↳ hep-lathep-phPRD(2020)·118 citations
22. 22*

    Search for a Dark Leptophilic Scalar at BABAR

    The BABAR Collaboration

    Many scenarios of physics beyond the Standard Model predict the existence of new gauge singlets, which might be substantially lighter than the weak scale. The experimental constraints on additional scalars with masses in the MeV to GeV range could be significantly weakened if they interact predominantly with leptons rather than quarks. At an $e^{+}{e}^{-}$ collider, such a leptophilic scalar (${\varphi }_L$) would be produced predominantly through radiation from a $\tau$ lepton. We report herein a search for $e^{+}{e}^{-}\to {\tau }^{+}{\tau }^{-}{\varphi }_L$, ${\varphi }_L\to {\ell }^{+}{\ell }^{-}$ ($\ell =e,\mu$) using data collected by the BABAR experiment at SLAC. No significant signal is observed, and we set limits on the ${\varphi }_L$ coupling to leptons in the range 0.04 < m${}_{{\varphi }_L}$ < 7.0 GeV. These bounds significantly improve upon the current constraints, excluding almost entirely the parameter space favored by the observed discrepancy in the muon anomalous magnetic moment below 4 GeV at 90\% confidence level.

    ↳ hep-exhep-phPRL(2020)·49 citations
23. 23*

    Soft gamma rays from low accreting supermassive black holes and connection to energetic neutrinos

    Shigeo S. Kimura🇯🇵 · Kohta Murase🇺🇸 · Peter Mészáros🇺🇸

    The Universe is filled with a diffuse background of MeV gamma-rays and PeV neutrinos, whose origins are unknown. Here, we propose a scenario that can account for both backgrounds simultaneously. Low-luminosity active galactic nuclei have hot accretion flows where thermal electrons naturally emit soft gamma rays via Comptonization of their synchrotron photons. Protons there can be accelerated via turbulence or reconnection, producing high-energy neutrinos via hadronic interactions. We demonstrate that our model can reproduce the gamma-ray and neutrino data. Combined with a contribution by hot coronae in luminous active galactic nuclei, these accretion flows can explain the keV -- MeV photon and TeV -- PeV neutrino backgrounds. This scenario can account for the MeV background without non-thermal electrons, suggesting a higher transition energy from the thermal to non-thermal Universe than expected. Our model is consistent with X-ray data of nearby objects, and testable by future MeV gamma-ray and high-energy neutrino detectors.

    ↳ astro-ph.HEhep-phNature Commun.(2021)·46 citations
24. 24*

    Finite-volume formalism in the $2\stackrel{H_I+H_I}{\to }2$ transition: an application to the lattice QCD calculation of double beta decays

    Xu Feng🇨🇳 · Lu-Chang Jin🇺🇸 · Zi-Yu Wang🇨🇳 · Zheng Zhang🇨🇳

    We present the formalism for connecting a second-order electroweak $2\stackrel{H_I+H_I}{\to }2$ transition amplitudes in the finite volume (with two hadrons in the initial and final states) to the physical amplitudes in the infinite volume. Our study mainly focus on the case where the low-lying intermediate state consists of two scattering hadrons. As a side product we also reproduce the finite-volume formula for $2\stackrel{H_I}{\to }2$ transition, originally obtained by Briceño and Hansen. With the available finite-volume formalism, we further discuss how to treat with the finite-volume problem in the double beta decays $nn\to ppee\bar{\nu }\bar{\nu }$ and $nn\to ppee$.

    ↳ hep-lathep-phnucl-thPRD(2021)·29 citations
25. 25*

    Quantum criticality of magnetic catalysis in two-dimensional correlated Dirac fermions

    Yasuhiro Tada🇯🇵

    We study quantum criticality of the magnetic field induced charge density wave (CDW) order in correlated spinless Dirac fermions on the $\pi$-flux square lattice at zero temperature as a prototypical example of the magnetic catalysis, by using the infinite density matrix renormalization group. It is found that the CDW order parameter $M(B)$ exhibits an anomalous magnetic field $(B)$ scaling behavior characteristic of the $(2+1)$-dimensional chiral Ising universality class near the quantum critical point, which leads to a strong enhancement of $M(B)$ compared with a mean field result. We also establish a global phase diagram in the interaction-magnetic field plane for the fermionic quantum criticality.

    ↳ cond-mat.str-elhep-phPRResearch(2020)·9 citations
26. 26*

    Flavor non-singlet parton distribution functions from lattice QCD at physical quark masses via the pseudo-distribution approach

    Manjunath Bhat🇵🇱 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Aurora Scapellato🇵🇱

    One of the great challenges of QCD is to determine the partonic structure of the nucleon from first principles. In this work, we provide such a determination of the flavor non-singlet ($u-d$) unpolarized parton distribution function (PDF), utilizing the non-perturbative formulation of QCD on the lattice. We apply Radyushkin's pseudo-distribution approach to lattice results obtained using simulations with the light quark mass fixed to its physical value; this is the first ever attempt for this approach directly at the physical point. The extracted coordinate-space matrix elements are used to find the relevant physical Ioffe time distributions from a matching procedure. The full Bjorken-$x$ dependence of PDFs is resolved using several reconstruction methods to tackle the ill-conditioned inverse problem encountered when using discrete lattice data. We consider both the valence distribution $q_v$ and the combination with antiquarks $q_v+2\bar{q}$, related to, respectively, the real and imaginary part of extracted matrix elements. Good agreement is found with PDFs from global fits already within statistical uncertainties and it is further improved by quantifying several systematic effects. The results presented here are the first ever \emph{ab initio} determinations of PDFs fully consistent with global fits in the whole $x$-range. Thus, they pave the way to investigating a wider class of partonic distributions, such as e.g.\ singlet PDFs and generalized parton distributions. Therefore, essential and yet missing first-principle insights can be achieved, complementing the rich experimental programs dedicated to the structure of the nucleon.

    ↳ hep-lathep-exhep-phnucl-thPRD(2021)·88 citations
27. 27*

    Impact of ion mobility on nonlinear Compton scattering of an ultra-intense laser pulse in a plasma

    F. Mackenroth🇩🇪

    We demonstrate that the nontrivial dispersion of a plasma driven by a high-intensity laser pulse qualitatively affects fundamental nonperturbative QED processes triggered by the laser pulse even in the case that no electrons remain in the interaction volume, e.g., due to ponderomotive expulsion. In the electron-free case this plasma effect is mediated by the response current of the residual ions as a dispersive effect on the laser propagation. The residual ions hence act as an effective background to the propagating electromagnetic laser field. We demonstrate that this has an impact on the fundamental nonlinear QED process of photon emission by an electron upon absorption of a large number of laser photons, called nonlinear Compton scattering. In two exemplary cases we find the ion plasma to suppress and enhance the photon emission rate by approximately $10\%$ for an intermediate and high laser intensity, respectively. The latter enhancement has no classical analog.

    ↳ physics.plasm-phhep-ph1 citation
28. 28*

    On the propagation of neutrinos through the Earth

    M. de Jong🇳🇱

    The Earth is commonly used as a natural filter for the operation of deep-underground and deep-sea neutrino telescopes. By selecting events pointing in upward directions, the background of muons produced by interactions of cosmic rays in the Earth' atmosphere above the detector can effectively be suppressed. The surviving neutrinos traversed a large part of the Earth before being detected. It is commonly assumed that the detected neutrinos go in a straight line through the Earth without loosing energy. A first study has been made of the propagation of neutrinos through the Earth which includes the effects of the charged-current as well as neutral-current interactions. It is found that this leads to an increase of the detectable flux of neutrinos.

    ↳ astro-ph.HEastro-ph.IMhep-ph0 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.