Fri·Dec 11, 2020Friday·December 11, 2020

1. 01*

   Off-shell Higgs Couplings in $H^{\ast }\to ZZ\to \ell \ell \nu \nu$

   Dorival Gonçalves🇺🇸 · Tao Han🇺🇸 · Sze Ching Iris Leung🇺🇸 · Han Qin🇺🇸

   We explore the new physics reach for the off-shell Higgs boson measurement in the $pp\to H^{\ast }\to Z({\ell }^{+}{\ell }^{-})Z(\nu \bar{\nu })$ channel at the high-luminosity LHC. The new physics sensitivity is parametrized in terms of the Higgs boson width, effective field theory framework, and a non-local Higgs-top coupling form factor. Adopting Machine-learning techniques, we demonstrate that the combination of a large signal rate and a precise phenomenological probe for the process energy scale, due to the transverse $ZZ$ mass, leads to significant sensitivities beyond the existing results in the literature for the new physics scenarios considered.

   hep-phhep-exPLB(2021)·22 citations
2. 02*

   Neutrino lines from DM decay induced by high-scale seesaw interactions

   Rupert Coy🇧🇪 · Thomas Hambye🇧🇪

   If the stability of the dark matter (DM) particle is due to an accidental symmetry, nothing prevents UV physics from destabilising it by inducing DM decays suppressed by powers of the UV scale. The seesaw physics, presumably at the origin of neutrino mass, could induce such a decay. We show that if the seesaw scale lies around the usual Weinberg operator scale, the induced DM decay could generically lead to neutrino lines whose intensity is of the order of the present sensitivity of neutrino telescopes. We illustrate this possibility with models in which the DM is made of the gauge boson(s) of an abelian or non-abelian gauge symmetry.

   hep-phJHEP(2021)·15 citations
3. 03*

   The neutron star inner crust: an empirical essay

   Luiz L. Lopes🇧🇷

   In this work we study how the small contribution of the inner crust to the total equation of state (EoS) of a neutron star affects its mass-radius relation, focusing on the canonical mass of 1.4$M_{\odot }$. We build empirical EoS of the kind - $p=K{ϵ}^{\gamma }+b$ - in the range of 0.003 fm${}^{-3}<n<$0.08 fm${}^{-3}$ and also calculate the speed of sound in this region. We see that different behaviours of the speed of sound can affect the radius of the canonical star by more than 1.1 km. This result can help us understand extreme results as GW170817, where some studies indicate that the radius of the canonical star cannot exceed 11.9 km.

   hep-phastro-ph.HEnucl-thEPL(2021)·14 citations
4. 04*

   CP violation in mixing and oscillations for leptogenesis with quasi-degenerate neutrinos

   J. Racker🇦🇷

   We study the sources of CP violation for baryogenesis models with quasi-degenerate neutrinos. Our approach is to use the renormalized propagator in a quantum field theory model of neutrino oscillations, paying close attention to unitarity requirements. From the probabilities of lepton number violating processes obtained in this way, we derive a source term for the time evolution of the lepton asymmetry. The source term has contributions that can be identified with CP violation from mixing, oscillations and interference between both. Given that this source term does not involve processes with unstable particles in the initial or final states, neither does it require to calculate number densities of neutrinos, no subtraction of real intermediate states must be performed. In equilibrium the source term is null, as demanded by unitarity and CPT invariance, due to a cancellation between the terms coming from CP violation in mixing and oscillations. The calculations are done in a simple scalar toy model, and the resummed propagator is diagonalized at first order in the decay widths over the mass difference. We also comment on the effect of the interference term, which is mild at the order we work, but seems to become more important with increasing degeneracy.

   hep-phJHEP(2021)·7 citations
5. 05*

   Probing secret interactions of eV-scale sterile neutrinos with the diffuse supernova neutrino background

   Mary Hall Reno🇺🇸 · Yu Seon Jeong🇨🇭 · Sergio Palomares-Ruiz🇪🇸 · Ina Sarcevic🇺🇸

   While three flavors of "active" neutrinos are consistent with mixing angle results within error bars, there are anomalies may be hints of physics beyond the standard model that can accommodate a fourth mostly "sterile" neutrino species with an eV-scale mass and a mixing angle with active neutrinos of order ${\theta }_0\simeq 0.1$. We describe a scenario with eV-scale sterile neutrinos that have self-interactions via a new gauge vector boson, a "secret" mediator $\varphi$. We show that their production in the early Universe via mixing with active neutrinos is consistent with Big Bang Nucleosynthesis and free-streaming constraints in the Cosmic Microwave Background epoch. For $M_{\varphi }=4-8$ keV and sterile neutrino coupling $g_s=10^{-4}$, we find that resonant interactions of diffuse supernova neutrinos with relic sterile neutrinos in transit to the Earth would cause spectral dips in the neutrino flux. We illustrate the corresponding (anti-)neutrino event distributions as a function of energy in the DUNE (Hyper-Kamiokande) detector.

   hep-phastro-ph.HEPoS(2021)·1 citation
6. 06*

   Role of nuclear gluon distribution on particle production in heavy ion collisions

   L. S. Moriggi🇧🇷 · G. M. Peccini🇧🇷 · M. V. T. Machado🇧🇷

   The transverse momentum spectra of hadrons is calculated from the unintegrated gluon distribution (UGD) within the $k_T$-factorization framework at small $x$. Starting from $pp$ collisions, the modification caused by the nuclear medium is incorporated in the UGD at high energies, which is related to the nuclear shadowing phenomenon. Moreover, we consider that particle production from minijet decaying is not enough to explain the $p_T$ spectra in $AA$ collisions due to collective phenomena that take place after the hard collision. The Boltzmann-Gibbs Blast Wave (BGBW) distribution is utilized in order to evaluate the distribution of particle production in equilibrium. Data from ALICE collaboration for $PbPb$ collisions at $\sqrt{s}=2.76$ TeV are analyzed and the nuclear modification factor for pion production is computed.

   hep-phPRD(2021)·15 citations
7. 07*

   $SU(4)$ Flavorful Portal Matter

   George N. Wojcik🇺🇸 · Thomas G. Rizzo🇺🇸

   In this paper, we present a model which attempts to unify a new dark sector force with a local $SU(3)$ flavor symmetry. Dark Matter (DM) and its potential interactions with the Standard Model (SM) continue to present a rich framework for model building. In the case of thermal DM of a mass between a few MeV and a few GeV, a compelling and much-explored framework is that of a dark photon/vector portal, which posits a new $U(1)$ "dark photon" which only couples to the SM via small kinetic mixing (KM) with the SM hypercharge. This mixing can be mediated at the one-loop level by portal matter (PM) fields which are charged under both the dark $U(1)$ and the SM gauge group. In earlier work, one of the authors has noted that models with appropriate portal matter content to produce finite and calculable kinetic mixing can arise from non-minimal dark sectors, in which the dark $U(1)$ is a subgroup of a larger gauge symmetry under which SM particles might have non-trivial representations. We expand on this idea here by constructing a model in which in which the dark $U(1)$ is unified with another popular extension to the SM gauge group, a local $SU(3)$ flavor symmetry. The full dark/flavor symmetry group is $SU(4{)}_F\times U(1{)}_F$, incorporating the local $SU(3)$ flavor symmetry with PM appearing as a vector-like "fourth generation" to supplement the three generations of the SM. To ensure finite contributions to KM, the SM gauge group is arranged into Pati-Salam multiplets. The new extended dark gauge group presents a variety of interesting experimental signatures, including non-trivial consequences of the flavor symmetry being unified with the dark sector.

   hep-phPRD(2022)·22 citations
8. 08*

   Cooling of young neutron stars and dark gauge bosons

   Deog Ki Hong🇰🇷 · Chang Sub Shin🇰🇷 · Seokhoon Yun🇮🇹

   The standard cooling scenario in the presence of nucleon superfluidity fits rather well to the observation of the neutron stars. It implies that the stellar cooling arguments could place a stringent constraint on the properties of novel particles. We study in particular the cooling rate induced by dark gauge bosons for very young neutron stars: remnants of Cassiopeia A and SN1987A. The cooling is dominantly contributed either by the nucleon pair breaking and formation in the core or by the electron bremsstrahlung in the crust, depending on the age of the stars and the form of the couplings. We compute how much the cooling curve of the young neutron stars could be modified by the extra dark gauge boson emission and obtain the bound for the dark gauge boson when its mass is lower than $\mathcal{O}(0.1)\mathrm{MeV}$; for the dark photon we find the mixing parameter times its mass $\epsilon m_{{\gamma }^{\prime }}<1.5\times 10^{-8}\mathrm{MeV}$ and for the $\mathrm{U}(1{)}_{B-L}$ gauge boson its coupling to nucleons and electrons $e^{\prime }<10^{-13}$. We also discuss the possibility that the rapid cooling of Cas A might provide a hint for the existence of the $\mathrm{U}(1{)}_{B-L}$ gauge boson.

   hep-phastro-ph.HEPRD(2021)·38 citations
9. 09*

   A generalized approach to study low as well as high $p_T$ regime of transverse momentum spectra

   Rohit Gupta🇮🇳 · Satyajit Jena🇮🇳

   A good understanding of the transverse momentum $(p_T)$ spectra is pivotal in the study of QCD matter created during the heavy-ion collision. Considering the difference in the underlying particle production mechanism, $p_T$ spectra can be divided into two distinct regions. Low-$p_T$ region corresponds to particle produced in soft-processes whereas particles produced in hard processes dominate the high-$p_T$ regime of the spectra. We will discuss a unified formalism to explain both low as well as high-$p_T$ region of the transverse momentum spectra in a consistent manner. This unified formalism is based on the generalisation of non-extensive statistical mechanics using the Pearson distribution. This generalised formalism also gives a strong insight into the study of elliptic flow in heavy-ion collision.

   hep-phPoS(2021)·0 citations
10. 10*

    Scalar Field Condensate Baryogenesis Model in Different Inflationary Scenarios

    Daniela Kirilova🇧🇬 · Mariana Panayotova🇧🇬

    We calculate the baryon asymmetry value generated in the Scalar Field Condensate (SCF) baryogenesis model obtained in several inflationary scenarios and different reheating models. We provide analysis of the baryon asymmetry value obtained for more than 70 sets of parameters of the SCF model and the following inflationary scenarios, namely: new inflation, chaotic inflation, Starobinsky inflation, MSSM inflation, quintessential inflation. We considered both cases of efficient thermalization after inflation and also delayed thermalization. We have found that SFC baryogenesis model produces baryon asymmetry by orders of magnitude bigger than the observed one for the following inflationary models: new inflation, new inflation model by Shafi and Vilenkin, MSSM inflation, chaotic inflation with high reheating temperature and the simplest Shafi-Vilenkin chaotic inflationary model. For these models strong diluting mechanisms are needed to reduce the resultant baryon excess at low energies to its observational value today. We have found that a successful generation of the observed baryon asymmetry is possible by SCF baryogenesis model in Modified Starobinsky inflation, chaotic inflation with low reheating temperature, chaotic inflation in SUGRA and Quintessential inflation.

    hep-phastro-ph.CO1 citation
11. 11*

    Using dipole processes to constrain the flavour of four-fermion effective interactions

    L. Vale Silva🇪🇸 · S. Jäger🇬🇧 · K. Leslie🇬🇧

    Dipole interactions encode a rich variety of phenomena, such as radiative decays and electric dipole moments in both quark and lepton sectors, which probe physics beyond the Standard Model up to very high energy scales; due to renormalization, non-dipole operators mix into dipole ones, thus possibly generating observable effects that can be investigated by those same phenomena. I consider four-fermion contact interactions for which the leading order mixing into dipoles happens at two-loops (i.e., when one-loop effects vanish) and for which this mixing can avoid small Yukawa couplings, and then explore the phenomenological consequences for flavour and $\mathbf{CP}$ violation coming from New Physics.

    hep-phPoS(2021)·6 citations
12. 12*

    Quantum fluctuations of energy in subsystems of a hot relativistic gas

    Arpan Das🇵🇱 · Wojciech Florkowski🇵🇱 · Radoslaw Ryblewski🇵🇱 · Rajeev Singh🇵🇱

    We derive a formula that defines quantum fluctuations of energy in subsystems of a hot relativistic gas. For small subsystem sizes we find substantial increase of fluctuations compared to those known from standard thermodynamic considerations. However, if the size of the subsystem is sufficiently large, we reproduce the result for energy fluctuations in the canonical ensemble. Our results are subsequently used in the context of relativistic heavy-ion collisions to introduce limitations of the concepts such as classical energy density or fluid element. In the straightforward way, our formula can be applied in other fields of physics, wherever one deals with hot and relativistic matter.

    hep-phhep-thnucl-thActa Phys.Polon.B(2021)·10 citations
13. 13*

    Finite Size Effects on the Chiral Phase Transition of Quantum Chromodynamics

    Shen-Song Wan🇨🇳 · Daize Li🇨🇳 · Bonan Zhang🇨🇳 · Marco Ruggieri🇨🇳

    We study the effect of periodic boundary conditions on chiral symmetry breaking and its restoration in Quantum Chromodynamics. As an effective model of the effective potential for the quark condensate, we use the quark-meson model, while the theory is quantized in a cubic box of size $L$. After specifying a renormalization prescription for the vacuum quark loop, we study the condensate at finite temperature, $T$, and quark chemical potential, $\mu$. We find that lowering $L$ leads to a catalysis of chiral symmetry breaking. The excitation of the zero mode leads to a jump in the condensate at low temperature and high density, that we suggest to interpret as a gas-liquid phase transition that takes place between the chiral symmetry broken phase (hadron gas) and chiral symmetry restored phase (quark matter). We characterize this intermediate phase in terms of the increase of the baryon density, and of the correlation length of the fluctuations of the order parameter: for small enough $L$ the correlation domains occupy a substantial portion of the volume of the system, and the fluctuations are comparable to those in the critical region. For these reasons, we dub this phase as the {\it subcritical liquid}. The qualitative picture that we draw is in agreement with previous studies based on similar effective models. We also clarify the discrepancy on the behavior of the critical temperature versus $L$ found in different models.

    hep-phhep-latnucl-th7 citations
14. 14*

    Probing Top Changing Neutral Higgs Couplings at Colliders

    Wei-Shu Hou🇹🇼 · Tanmoy Modak🇩🇪

    The $h(125)$ boson, discovered only in 2012, is lower than the top quark in mass, hence $t\to ch$ search commenced immediately thereafter, with current limits at the per mille level and improving. As the $t\to ch$ rate vanishes with the $h$-$H$ mixing angle $\cos \gamma \to 0$, we briefly review the collider probes of the top changing $tcH/tcA$ coupling ${\rho }_{tc}$ of the exotic $CP$-even/odd Higgs bosons $H/A$. Together with an extra top conserving $ttH/ttA$ coupling ${\rho }_{tt}$, one has an enhanced $cb{H}^{+}$ coupling alongside the familiar $tb{H}^{+}$ coupling, where $H^{+}$ is the charged Higgs boson. The main processes we advocate are $cg\to tH/A\to tt\bar{c},tt\bar{t}$ (same-sign top and triple-top), and $cg\to b{H}^{+}\to bt\bar{b}$. We also discuss some related processes such as $cg\to thh$, $tZH$ that depend on $\cos \gamma$ being nonzero, comment briefly on $gg\to H/A\to t\bar{t},t\bar{c}$ resonant production, and touch upon the ${\rho }_{tu}$ coupling.

    hep-phhep-exhep-latMod.Phys.Lett.A(2021)·36 citations
15. 15*

    Leptoquarks and Real Singlets: A Richer Scalar Sector Behind the Origin of Dark Matter

    Francesco D'Eramo🇮🇹 · Nejc Košnik🇸🇮 · Federico Pobbe🇮🇹 · Aleks Smolkovič🇸🇮 · Olcyr Sumensari🇨🇭

    We investigate scenarios with $\mathcal{O}(1\mathrm{TeV})$ scalar leptoquarks that act as portals between the Standard Model and Dark Matter. We assume that Dark Matter is a scalar singlet $S$ which couples to a scalar leptoquark $\Delta$ and the Higgs boson via the terms in the scalar potential. In addition, the leptoquark is endowed with Yukawa couplings to quarks and leptons that may address the anomalies in $B$ meson decays. We consider the $SS$ annihilation cross sections to estimate the Dark Matter relic abundance and explore the interplay between astrophysical, collider and flavour physics bounds on such models. In the heavy Dark Matter window, $m_S>m_{\Delta }$, the leptoquark portal becomes the dominant mechanism to explain the Dark Matter abundance. We find that the leptoquark Yukawa couplings, relevant for quark and lepton flavour physics, are decoupled from the dark matter phenomenology. By focussing on a scenario with a single leptoquark state, we find that relic density can only be explained when both $\Delta$ and $S$ masses are lighter than $\mathcal{O}(10\mathrm{TeV})$.

    hep-phastro-ph.COPRD(2021)·15 citations
16. 16*

    Heavy Neutrino-Antineutrino Oscillations in Quantum Field Theory

    Stefan Antusch🇨🇭 · Johannes Rosskopp🇨🇭

    It has been proposed that the coherent propagation of long-lived heavy neutrino mass eigenstates can lead to an oscillating rate of lepton number conserving (LNC) and violating (LNV) events, as a function of the distance between the production and displaced decay vertices. We discuss this phenomenon, which we refer to as heavy neutrino-antineutrino oscillations, in the framework of quantum field theory (QFT), using the formalism of external wave packets. General formulae for the oscillation probabilities and the number of expected events are derived and the coherence and localisation conditions that have to be satisfied in order for neutrino-antineutrino oscillations to be observable are discussed. The formulae are then applied to a low scale seesaw scenario, which features two nearly mass degenerate heavy neutrinos that can be sufficiently long lived to produce a displaced vertex when their masses are below the $W$ boson mass. The leading and next-to-leading order oscillation formulae for this scenario are derived. For an example parameter point used in previous studies, the kinematics of the considered LNC/LNV processes are simulated, to check that the coherence and localisation conditions are satisfied. Our results show that the phenomenon of heavy neutrino-antineutrino oscillations can indeed occur in low scale seesaw scenarios and that the previously used leading order formulae, derived with a plane wave approach, provide a good approximation for the considered example parameter point.

    hep-phJHEP(2021)·26 citations
17. 17*

    Plane-wave model of neutrino oscillations revisited

    Winfried A. Mitaroff🇦🇹

    The phenomenology of massive neutrinos -- flavour mixing in the lepton sector causing oscillations between different neutrino-types along their propagation over macroscopic distances in vacuum -- aims at relating observable quantities (oscillation frequency or, equivalently, oscillation length) to the neutrino properties: mixing angles ${\theta }_{ij}$ and mass-squared differences $\Delta m_{ij}^2$. Calculation of the probabilities for a given neutrino-type either to survive or to mutate into another type, as functions of momentum $p$ and travelling distance $L$, are properly based on wave-packet models of varying complexity. Approximations neglecting subtle effects like decoherence result in the standard oscillation formulae with terms proportional to ${\sin }^2(\Delta m_{ij}^{2}L/4p)$. The same result may also be derived by a simple plane-wave model as shown in most textbooks. However, those approaches rely on unphysical a-priory assumptions: either "equal energy" or "equal velocity" or "equal momentum" in the phases of different mass eigenstates -- which are refuted elsewhere. In addition, some assume tacitly that interference occurs at time $t=L$. This study re-examines the plane-wave model. No unphysical assumption is necessary for deriving the standard formulae: a heuristic approach relies only on carefully defining interference at time $t=L/\beta$, and is justified by coherence arguments based in a qualitative way on wave-packets.

    hep-ph0 citations
18. 18*

    Vacuum Stability Constraints on Flavor Mixing Parameters and Their Effect on Gluino Decays

    S. Ajmal🇵🇰 · M. Rehman🇵🇰 · F. Tahir🇵🇰

    In this article, we study the two body gluino decays $\tilde{g}\to {\tilde{u}}_i{\bar{u}}_g$, $\tilde{g}\to {\tilde{d}}_i{\bar{d}}_g$ with $i=1,2,...6$ and $g=1,2,3$ in the Minimal Supersymmetric Standard Model (MSSM) with quark flavour violation (QFV). At the outset, constraints on QFV parameters ${\delta }_{ij}^{U/D(LR)}$ and ${\delta }_{ij}^{U/D(RL)}$ with $i,j=1,2,3$ and $(i\ne j)$ are calculated for a specific set of MSSM parameters using charge and color breaking minima (CCB) and unbounded from below minima (UFB) conditions. These constraints are more stringent compared to the constraints coming from B-physics observables (BPO), that are already available in literature. In the second step, we re-calculate the partial decay widths of $\tilde{g}\to {\tilde{u}}_i{\bar{u}}_g$, $\tilde{g}\to {\tilde{d}}_i{\bar{d}}_g$ for the allowed range of QFV parameters. The partial decay widths can reach upto 120 GeV in the RR sector of the squarks mass matrices while in the LL sector it can be $\approx 90$ GeV. The QFV in the LR/RL sector is usually ignored due to stringent CCB andd UFB constraints, however, our analysis reveals that this mixing can contribute upto $\approx 12$ GeV for some parameter points and should not be ignored. We hope that these results will prove helpful for the experimental searches of gluinos at the current and future colliders.

    hep-ph0 citations
19. 19*

    Cosmic antihelium-3 nuclei sensitivity of the GAPS experiment

    N. Saffold🇺🇸 · T. Aramaki🇺🇸 · R. Bird🇺🇸 · M. Boezio🇮🇹 · S. E. Boggs🇺🇸 · V. Bonvicini🇮🇹 · D. Campana🇮🇹 · W. W. Craig🇺🇸 · P. von Doetinchem🇺🇸 · E. Everson🇺🇸 · L. Fabris🇺🇸 · H. Fuke🇯🇵 and 43 other authors

    The General Antiparticle Spectrometer (GAPS) is an Antarctic balloon experiment designed for low-energy (0.1$-$0.3 GeV/$n$) cosmic antinuclei as signatures of dark matter annihilation or decay. GAPS is optimized to detect low-energy antideuterons, as well as to provide unprecedented sensitivity to low-energy antiprotons and antihelium nuclei. The novel GAPS antiparticle detection technique, based on the formation, decay, and annihilation of exotic atoms, provides greater identification power for these low-energy antinuclei than previous magnetic spectrometer experiments. This work reports the sensitivity of GAPS to detect antihelium-3 nuclei, based on full instrument simulation, event reconstruction, and realistic atmospheric influence simulations. The report of antihelium nuclei candidate events by AMS-02 has generated considerable interest in antihelium nuclei as probes of dark matter and other beyond the Standard Model theories. GAPS is in a unique position to detect or set upper limits on the cosmic antihelium nuclei flux in an energy range that is essentially free of astrophysical background. In three 35-day long-duration balloon flights, GAPS will be sensitive to an antihelium flux on the level of $1.3_{-1.2}^{+4.5}\cdot 10^{-6}{\mathrm{m}}^{-2}\mathrm{s}{\mathrm{r}}^{-1}{\mathrm{s}}^{-1}(\mathrm{GeV}/n{)}^{-1}$ (95% confidence level) in the energy range of 0.11$-$0.3 GeV/$n$, opening a new window on rare cosmic physics.

    hep-phastro-ph.HEhep-exAstropart.Phys.(2021)·46 citations
20. 20*

    Domain walls and CP violation with left right supersymmetry:implications for leptogenesis and electron EDM

    Piyali Banerjee🇮🇳 · Urjit Yajnik🇮🇳

    Low scale leptogenesis scenarios are difficult to verify due to our inability to relate the parameters involved in the early universe processes with the low energy or collider observables. Here we show that one can in principle relate the parameters giving rise to the transient $CP$ violating phase involved in leptogenesis with those that can be deduced from the observation of electric dipole moment (EDM) of the electron. We work out the details of this in the context of the left right symmetric supersymmetric model (LRSUSY) which provides a strong connection between such parameters. In particular, we show that baryon asymmetry requirements imply the scale $M_{B-L}$ of $U(1{)}_{B-L}$ symmetry breaking to be larger than $10^{4.5}\mathrm{GeV}$. Moreover the scale $M_R$ of $SU(2{)}_R$ symmetry breaking is tightly constrained to lie in a narrow band significantly below $M_{B-L}^2/M_{EW}$. These are the most stringent constraints on the parameter space of LRSUSY model being considered.

    hep-phJHEP(2021)·7 citations
21. 21*

    The fate of $V_1$ vector leptoquarks: the impact of future flavour data

    C. Hati🇩🇪 · J. Kriewald🇫🇷 · J. Orloff🇫🇷 · A. M. Teixeira🇫🇷

    Motivated by the recent experimental progress on the $B$-meson decay anomalies (in particular the angular observables in $B\to K^{\ast }\mu \mu$), we rely on a simplified-model approach to study the prospects of vector leptoquarks in what concerns numerous flavour observables, identifying several promising decay modes which would allow to (indirectly) probe such an extension. Our findings suggest that the confirmation of the $B$-meson decay anomalies, in parallel with positive signals (at Belle II or LHCb) for $\tau \to \varphi \mu$, $B_{(s)}$-meson decays to ${\tau }^{+}{\tau }^{-}$ and ${\tau }^{+}{\mu }^{-}$ (${\tau }^{+}{e}^{-}$) final states, as well as an observation of certain charged lepton flavour violation decays (at COMET or Mu2e), would contribute to strengthen the case for this scenario. We also illustrate how the evolution of the experimental determination of $R_{D^{(\ast )}}$ could be instrumental in falsifying an explanation of the anomalous $B$-meson decay data via a vector $V_1$ leptoquark.

    hep-phhep-exEPJC(2021)·26 citations
22. 22*

    GeV Scale Inelastic Dark Matter with Dark Photon Mediator via Direct Detection and Cosmological/Laboratory Constraints

    Hong-Jian He🇨🇳 · Yu-Chen Wang🇨🇳 · Jiaming Zheng🇨🇳

    We propose a new candidate of GeV scale inelastic dark matter (DM). Our construction has an anomaly-free $U(1{)}_X^{}$ gauge group with dark photon mediator, and can realize either scalar or fermionic inelastic DM. It is highly predictive and testable. We study the scattering rate of light inelastic DM with electrons in the XENON1T experiment and with nuclei in the XENON1T, CRESST-III, CDEX-1B and DarkSide-50 experiments. We resolve the recent XENON1T anomaly via electron recoil detection. Combining the XENON1T constraints from both electron recoils and nuclear recoils (including Migdal effect), we predict the inelastic DM mass $\lesssim 1.5$GeV. We further analyze the bounds by the DM relic abundance, the lifetime of the heavier DM component, and laboratory constraints, from which we identify the viable parameter space for the future probe. This provides an important benchmark for the theories and experimental tests of GeV scale inelastic DM.

    hep-phastro-ph.COhep-exPRD(2021)·25 citations
23. 23*

    Mixed EW-QCD two-loop amplitudes for $q\bar{q}\to {\ell }^{+}{\ell }^{-}$ and ${\gamma }_5$ scheme independence of multi-loop corrections

    Matthias Heller🇩🇪 · Andreas von Manteuffel🇺🇸 · Robert M. Schabinger🇺🇸 · Hubert Spiesberger🇩🇪

    We perform a dedicated study of the $q\bar{q}$-initiated two-loop electroweak-QCD Drell-Yan scattering amplitude in dimensional regularization schemes for vanishing light quark and lepton masses. For the relative order $\alpha$ and ${\alpha }_s$ one-loop Standard Model corrections, details of our comparison to the original literature are given. The infrared pole terms of the mixed two-loop amplitude are governed by a known generalization of the dipole formula and we show explicitly that exactly the same two-loop polarized hard scattering functions are obtained in both the standard 't Hooft-Veltman-Breitenlohner-Maison ${\gamma }_5$ scheme and Kreimer's anticommuting ${\gamma }_5$ scheme.

    hep-phJHEP(2021)·47 citations
24. 24*

    Pulse envelope effect on nonlinear Compton scattering in electron-laser collisions

    B. King🇬🇧

    Nonlinear Compton scattering is calculated for the collision of an electron with a plane wave pulse. A mid infra-red (IR) peak arises in the photon spectrum due to long-range interference associated with the pulse envelope. The case of a flat-top pulse is studied as a toy model for pulse envelope effects and reduced to two final-state momentum integrations; the case of a sine-squared pulse is studied numerically. A perturbative expansion in charge-field coupling reveals that already at intermediate intensities, many orders are required to correctly capture the structure of the mid-IR peak. By regularising the classical result, it is shown that the mid-IR peak is due to plane-wave ponderomotive effects on the pulse envelope. Finally, it is shown that the mid-IR peak can be isolated using energy, angle and polarisation filters.

    hep-phPRD(2021)·27 citations
25. 25*

    Pion crystals hosting topologically stable baryons

    Fabrizio Canfora🇨🇱 · Stefano Carignano🇪🇸 · Marcela Lagos🇨🇱 · Massimo Mannarelli🇮🇹 · Aldo Vera🇨🇱

    We construct analytic (3+1)-dimensional inhomogeneous and topologically non-trivial pion systems using chiral perturbation theory. We discuss the effect of isospin asymmetry with vanishing electromagnetic interactions as well as some particular configurations with non-vanishing electromagnetic interactions. The inhomogeneous configurations of the pion fields are characterized by a non-vanishing topological charge that can be identified with baryons surrounded by a cloud of pions. This system supports a topologically protected persistent superflow. When the electromagnetic field is turned on the superflow corresponds to an electromagnetic supercurrent.

    hep-phcond-mat.quant-gasnucl-thPRD(2021)·36 citations
26. 26*

    Partial decay widths of baryons in the spin-momentum operator expansion method

    A.V. Sarantsev🇩🇪

    The covariant operator expansion method used by the Bonn-Gatchina group for the analysis of the meson photoproduction data is extended on the case of meson electro-production reactions. The angular dependence of the partial waves is deduced and the obtained amplitudes are compared with those used in other analyses of the electro-production reactions

    ↳ nucl-thhep-ph0 citations
27. 27*

    RI/MOM renormalization of the quasi-PDF in lattice regularization

    Kuan Zhang🇨🇳 · Yuan-Yuan Li🇨🇳 · Yi-Kai Huo🇨🇳 · Andreas Schäfer🇩🇪 · Peng Sun🇨🇳 · Yi-Bo Yang🇨🇳

    We analyze the lattice spacing dependence for the pion unpolarized matrix element of a quark bilinear operator with Wilson link (quasi-PDF operator) in the rest frame, using 13 lattice spacings ranging from 0.032 fm to 0.121 fm. We compare results for three different fermion actions with or without good chiral symmetry on dynamical gauge ensembles from three collaborations. This investigation is motivated by the fact that the gauge link generates an $1/a$ divergence, the cancelation of which in many ratios can be numerically tricky. Indeed, our results show that this cancelation deteriorates with decreasing lattice spacing, and that the RI/MOM method leaves a linearly divergent residue for quasi-PDFs. We also show that in the Landau gauge the interaction between the Wilson link and the external state results in a linear divergence which depends on the discretized fermion action.

    ↳ hep-lathep-phPRD(2021)·37 citations
28. 28*

    Vortex particles in axially symmetric fields and applications of the quantum Busch theorem

    Dmitry Karlovets🇷🇺

    The possibilities to accelerate vortex electrons with orbital angular momentum (OAM) to relativistic energies and to produce vortex ions, protons, and other charged particles crucially depend on whether the OAM is conserved during the acceleration and on how phase space of the wave packet evolves. We show that both the OAM and a mean emittance of the packet, the latter obeying the Schrödinger uncertainty relation, are conserved in axially symmetric fields of electric and magnetic lenses, typical for accelerators and electron microscopes, as well as in Penning traps, while a linear approximation of weakly inhomogeneous fields works much better for single packets than for classical beams. We analyze quantum dynamics of the packet's rms radius $⟨{\rho }^2⟩$, relate this dynamics to a generalized form of the van Cittert-Zernike theorem, applicable at arbitrary distances from a source and for non-Gaussian packets, and adapt the Courant-Snyder formalism to describe the evolution of the wave packet's phase space. The vortex particles can therefore be accelerated, focused, steered, trapped, and even stored in azimuthally symmetric fields and traps, somewhat analogously to the classical angular-momentum-dominated beams. Moreover, we give a quantum version of the Busch theorem, which states how one can produce vortex electrons with a magnetized cathode during either field- or photoemission, as well as vortex ions and protons by using a magnetized stripping foil employed to change a charge state of ions. Spatial coherence of the packets plays a crucial role in these applications and we provide the necessary estimates for particles of different masses.

    ↳ quant-phhep-phphysics.acc-phNew J.Phys.(2021)·38 citations
29. 29*

    Energy Loss in Holographic Anisotropic Model for Heavy Quarks in External Magnetic Field

    Irina Ya. Aref'eva🇷🇺 · Kristina Rannu🇷🇺 · Pavel Slepov🇷🇺

    Energy loss in anisotropic hot dense QGP in external magnetic field is studied within holographic approach. Energy loss is calculated by estimation of behaviour of the spatial Wilson loops using the effective potential technique. We examine the dependence of the effective potential on the spatial Wilson loops orientation in fully anisotropic background. For this purpose we obtain general formulas for the effective potential and study appearance of the effective potential dynamical wall. We consider particular fully anisotropic model [arXiv:2011.07023] supported by Einstein-Dilaton-three-Maxwell action. The effective potential strongly depends on the parameters of anisotropy and magnetic field, therefore the energy loss depends on physical parameters $-$ $T$, $\mu$, $c_B$ and orientation. Orientation is determined by angles between the moving heavy quark velocity, the axis of heavy ions collision and their impact parameter vector.

    ↳ hep-thhep-ph31 citations
30. 30*

    Three-body capture, ejection, and the demographics of bound objects in binary systems

    Benjamin V. Lehmann🇺🇸 · Olivia G. Ross🇺🇸 · Ava Webber🇺🇸 · Stefano Profumo🇺🇸

    We study the capture of light objects of arbitrary velocity by binary systems. Extending results for the capture of comets in the solar system, we develop a simple geometric characterization of the capture cross section, leading directly to the distribution of orbital parameters of captured objects. We use the same framework to study the lifetimes of these bound orbits prior to ejection, and find that a simplified version of the Öpik--Arnold approach readily yields a closed-form estimate for the ejection rate that agrees well with numerical experiments. Without any detailed-balance assumptions, our results make manifest the characteristics of close encounters leading to capture and ejection. As an application of our results, we demonstrate the estimation of the equilibrium population of captured dark matter particles in a binary system.

    ↳ astro-ph.SRastro-ph.EPhep-phMNRAS(2021)·9 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.