Mon·Mar 29, 2021Monday·March 29, 2021

1. 01*

   R-parity from string compactification

   Jihn E. Kim🇰🇷

   The strategy for assigning $Z_{4R}$ parity in the string compactification is presented. For the visible sector, an anti-SU(5) (flipped-SU(5)) grand unification (GUT) model with three families is used to reduce the number of representations compared to the number in the minimal supersymmetric standard models (MSSMs). The SO(32) heterotic string is used to allow a large nonabelian gauge group SU($N$), $N\ge 9$, for the hidden sector such that the number of extra U(1) factors is small. A discrete subgroup of the gauge U(1)'s is defined as the $Z_{4R}$ parity. Spontaneous symmetry breaking of anti-SU(5) GUT is achieved by the vacuum expectation values of two index antisymmetric tensor Higgs fields ${10}_{+1}$ and ${\overline{10}}_{-1}$ that led to our word `anti-SU(5)'. In the illustrated example, the multiplicity 3 in one twisted sector allows the permutation symmetry $S_3$ that leads us to select the third family members and one MSSM pair of the Higgs quintets.

   hep-phhep-thPRD(2021)·3 citations
2. 02*

   Radiative lepton mass and muon $g-2$ with suppressed lepton flavor and CP violations

   Wen Yin🇯🇵

   The recent experimental status, including the confirmation of the muon $g-2$ anomaly at Fermilab, indicates a Beyond Standard Model (BSM) satisfying the following properties: 1) it enhances the $g-2$ 2) suppresses flavor violations, such as $\mu \to e\gamma$, 3) suppresses CP violations, such as the electron electric dipole moment (EDM). In this letter, I show that if the masses of heavy leptons are generated radiatively, the eigenbasis of the mass matrix and higher dimensional photon operators can be automatically aligned. As a result, the muon $g-2$ is enhanced but the EDM of the electron and $\mu \to e\gamma$ rate are suppressed. Phenomenology and applications of the mechanism to the B-physics anomalies are argued.

   hep-phJHEP(2021)·40 citations
3. 03*

   One-loop $W$ boson contributions to the decay $H\to Z\gamma$ in the general $R_{\xi }$ gauge

   Dzung Tri Tran🇻🇳 · Le Tho Hue🇻🇳 · Khiem Hong Phan🇻🇳

   One-loop $W$ boson contributions to the decay $H\to Z\gamma$ in the general $R_{\xi }$ gauge are presented. The analytical results are expressed in terms of well-known Passarino-Veltman functions which their numerical evaluations can be generated using {\tt LoopTools}. In the limit $d\to 4$, we have shown that these analytical results are independent of the unphysical parameter $\xi$ and consistent with previous results. The gauge parameter independence are also checked numerically for consistence. Our results are also well stable with different values of $\xi =0,1,100,$ and $\xi \to \infty$.

   hep-phPTEP(2021)·6 citations
4. 04*

   1-loop matching of a thermal Lorentz force

   M. Laine🇨🇭

   Studying the diffusion and kinetic equilibration of heavy quarks within a hot QCD medium profits from the knowledge of a coloured Lorentz force that acts on them. Starting from the spatial components of the vector current, and carrying out two matching computations, one for the heavy quark mass scale ($M$) and another for thermal scales ($\sqrt{MT}$, $T$), we determine 1-loop matching coefficients for the electric and magnetic parts of a Lorentz force. The magnetic part has a non-zero anomalous dimension, which agrees with that extracted from two other considerations, one thermal and the other in vacuum. The matching coefficient could enable a lattice study of a colour-magnetic 2-point correlator.

   hep-phhep-latJHEP(2021)·17 citations
5. 05*

   Spatiotemporal linear instability analysis of collective neutrino flavor conversion in 4-dimensional spacetime

   Taiki Morinaga🇯🇵

   In an environment with high-density neutrinos formed in a core-collapse supernova (CCSN), the neutrinos exhibit nonlinear and complex oscillation behaviors due to their self-interactions. The onset of this nonlinear oscillation can be investigated by linearizing the evolution equation for small perturbations around the flavor eigenstates. While the condition under which the flavor eigenstates are unstable has been investigated in many studies, how the perturbations evolve in spacetime has yet to be elucidated. In this paper, we analytically and correctly derive the asymptotic behaviors of the linear perturbations in 4-dimensional spacetime in the linear regime for a 2-beam neutrino model using the recently proposed Lefschetz thimble formulation. The result suggests that the perturbations grow in the directions between the two neutrino beams. We also briefly discuss the possible effects of neutrino flavor conversion on the explosion mechanism of a CCSN. In particular, the result implies that the flavor instability in the preshock region may propagate into the postshock region, contrary to the previous study focusing on the group velocity in 1-dimensional space. How to treat the case of a more realistic continuous spectrum is also discussed.

   hep-phastro-ph.HEPRD(2021)·5 citations
6. 06*

   Radiative and meson decays of $Y(4230)$ in flavor SU(3)

   Luciano Maiani🇮🇹 · Antonio D. Polosa🇮🇹 · Verónica Riquer🇮🇹

   The charmonium-like exotic states $Y(4230)$ and the less known $Y(4320)$, produced in $e^{+}{e}^{-}$ collisions, are sources of positive parity exotic hadrons in association with photons or pseudoscalar mesons. We analyze the radiative and pion decay channels in the compact tetraquark scheme, with a method that proves to work equally well in the most studied $D^{\ast }\to \gamma /\pi +D$ decays. The decay of the vector $Y$ into a pion and a $Z_c$ state requires a flip of charge conjugation and isospin that is described appropriately in the formalism used. Rates however are found to depend on the fifth power of pion momentum which would make the final states $\pi Z_c(4020)$ strongly suppressed with respect to $\pi Z_c(3900)$. The agreement with BES III data would be improved considering the $\pi Z_c(4020)$ events to be fed by the tail of the $Y(4320)$ resonance under the $Y(4230)$. These results should renovate the interest in further clarifying the emerging experimental picture in this mass region.

   hep-phSymmetry(2021)·5 citations
7. 07*

   Three loop correction in the formation of QGP droplet

   M. Jena · K. K. Gupta · S. Somorendro Singh

   Quark-gluon plasma (QGP) droplet formation is re-considered with the addition of three loop correction to the earlier loop factors in the mean field potential. The correction of the three loop factor increases stability in the droplet formations of QGP at different parametrization factors of the QGP fluid and it is in better agreement in comparison to the lattice results of pressure, energy density and other thermodynamic relations. This implies that the contribution of the three loop enhances in showing the characteristic features of the QGP fluid. It shows that increasing the loop increased the strength of parametrization value which we defined earlier as a number parameter of fluid dynamics. It indicates that the model with the loop correction boosts in explaining about the formation of QGP droplet in the expansion of early universe

   hep-phnucl-thIndian J.Phys.(2023)·0 citations
8. 08*

   Effect of magnetic field on jet transport coefficient $\hat{q}$

   Debjani Banerjee🇮🇳 · Prottoy Das🇮🇳 · Souvik Paul🇮🇳 · Abhi Modak🇮🇳 · Ankita Budhraja🇮🇳 · Sabyasachi Ghosh🇮🇳 · Sidharth K. Prasad🇮🇳

   We report the estimation of jet transport coefficient, $\hat{q}$ for quark- and gluon-initiated jets using a simple quasi-particle model in absence and presence of magnetic field. This model introduces a temperature and magnetic field-dependent degeneracy factor of partons, which is tuned by fitting the entropy density of lattice quantum chromodynamics data. At a finite magnetic field, $\hat{q}$ for quark jets splits into parallel and perpendicular components whose magnetic field dependence comes from two sources: the field-dependent degeneracy factor and the phase space part guided from the shear viscosity to entropy density ratio. Due to the electrically neutral nature of gluons, the estimation of $\hat{q}$ for gluon jets is affected only by the field-dependent degeneracy factor. In presence of a finite magnetic field, we find a significant enhancement in $\hat{q}$ for both quark- and gluon-initiated jets at low temperature, which gradually decreases towards high temperature. We compare the obtained results with the earlier calculations based on the anti-de Sitter/conformal field theory correspondence, and a qualitatively similar trend is observed. The change in $\hat{q}$ in presence of magnetic field is, however, quantitatively different for quark- and gluon-initiated jets. This is an interesting observation which can be explored experimentally to verify the effect of magnetic field on $\hat{q}$.

   hep-phhep-exnucl-exnucl-thPramana(2023)·7 citations
9. 09*

   Schwinger pair production of magnetic monopoles: momentum distribution for heavy-ion collisions

   Oliver Gould🇬🇧 · David L.-J. Ho🇬🇧 · Arttu Rajantie🇬🇧

   Magnetic monopoles may be produced by the dual Schwinger effect in strong magnetic fields. Today, the strongest known magnetic fields in the universe are produced fleetingly in heavy-ion collisions. We use the complex worldline instanton method to calculate the momentum distribution of magnetic monopoles produced in heavy-ion collisions, in an approximation that includes the effect of the magnetic field to all orders but neglects monopole self-interactions. The result saturates the preparation time-energy uncertainty principle, and yields a necessary ingredient for experimental monopole searches in heavy-ion collisions.

   hep-phPRD(2021)·37 citations
10. 10*

    Low-$x$ improved TMD approach to the lepto- and hadroproduction of a heavy-quark pair

    Tolga Altinoluk🇵🇱 · Cyrille Marquet🇫🇷 · Pieter Taels🇫🇷

    We study lepto- and hadroproduction of a heavy-quark pair in the ITMD factorization framework for dilute-dense collisions. Due to the presence of a nonzero quark mass and/or nonzero photon virtuality, new contributions appear compared to the cases of photo- and hadroproduction of dijets, for which the ITMD framework was originally derived. The extra terms are sensitive to gluons that are not fully linearly polarized. At small $x$ those gluons emerge only when saturation effects are taken into account, and in a proper way. As a result, in linear small-$x$ frameworks where gluon are fully linearly polarized, such contributions are absent. We show however that they are not always negligible, even for large gluon transverse momentum, due to the behavior of the off-shell hard factors.

    hep-phJHEP(2021)·38 citations
11. 11*

    A unified formalism to study the pseudorapidity spectra in heavy-ion collision

    Rohit Gupta🇮🇳 · Aman Singh Katariya🇮🇳 · Satyajit Jena🇮🇳

    The pseudorapidity distribution of charged hadron over a wide $\eta$ range gives us crucial information about the dynamics of particle production. Constraint on the detector acceptance, particularly at forward rapidities, demands a proper distribution function to extrapolate the pseudorapidity distribution to large $\eta$. In this work, we have proposed a phenomenological model based on Pearson statistical framework to study the pseudorapidity distribution. We have analyzed and fit data of charged hadrons produced in $Pb-Pb$ collision at $2.76$ TeV and $Xe-Xe$ collision at $5.44$ TeV using the proposed model.

    hep-phEPJA(2021)·3 citations
12. 12*

    Massive quarks in NLO dipole factorization for DIS: Longitudinal photon

    G. Beuf🇵🇱 · T. Lappi🇫🇮 · R. Paatelainen🇫🇮

    In this work, we will present the first complete calculation of the one-loop longitudinal photon-to-quark-antiquark light cone wave function, with massive quarks. The quark masses are renormalized in the pole mass scheme. The result is used to calculate the next-to-leading order correction to the high energy Deep Inelastic Scattering longitudinal structure function on a dense target in the dipole factorization framework. For massless quarks the next-to-leading order correction was already known to be sizeable, and our result makes it possible to evaluate it also for massive quarks.

    hep-phnucl-thPRD(2021)·61 citations
13. 13*

    Chiral Anomaly in SU(2)${}_R$-Axion Inflation and the New Prediction for Particle Cosmology

    Azadeh Maleknejad🇨🇭

    Upon embedding the axion-inflation in the minimal left-right symmetric gauge extension of the SM with gauge group $SU(2{)}_L\times SU(2{)}_R\times U(1{)}_{B-L}$, [arXiv:2012.11516] proposed a new particle physics model for inflation. In this work, we present a more detailed analysis. As a compelling consequence, this setup provides a new mechanism for simultaneous baryogenesis and right-handed neutrino creation by the chiral anomaly of $W_R$ in inflation. The lightest right-handed neutrino is the dark matter candidate. This setup has two unknown fundamental scales, i.e., the scale of inflation and left-right symmetry breaking $SU(2{)}_R\times U(1{)}_{B-L}\to U(1{)}_Y$. Sufficient matter creation demands the left-right symmetry breaking scale happens shortly after the end of inflation. Interestingly, it prefers left-right symmetry breaking scales above $10^{10}GeV$, which is in the range suggested by the non-supersymmetric SO(10) Grand Unified Theory with an intermediate left-right symmetry scale. Although $W_R$ gauge field generates equal amounts of right-handed baryons and leptons in inflation, i.e. $B-L=0$, in the Standard Model sub-sector $B-L_{SM}\ne 0$. A key aspect of this setup is that $SU(2{)}_R$ sphalerons are never in equilibrium, and the primordial $B-L_{SM}$ is conserved by the Standard Model interactions. This setup yields a deep connection between CP violation in physics of inflation and matter creation (visible and dark); hence it can naturally explain the observed coincidences among cosmological parameters, i.e., ${\eta }_B\simeq 0.3P_{\zeta }$ and ${\Omega }_{DM}\simeq 5{\Omega }_B$. The $SU(2{)}_R$-axion inflation comes with a cosmological smoking gun; chiral, non-Gaussian, and blue-tilted gravitational wave background, which can be probed by future CMB missions and laser interferometer detectors.

    hep-phastro-ph.COgr-qchep-thJHEP(2020)·29 citations
14. 14*

    First-order strong-field QED processes including the damping of particles states

    T. Podszus🇩🇪 · A. Di Piazza🇩🇪

    Volkov states are exact solutions of the Dirac equation in the presence of an arbitrary plane wave. Volkov states, as well as free photon states, are not stable in the presence of the background plane-wave field but "decay" as electrons/positrons can emit photons and photons can transform into electron-positron pairs. By using the solutions of the corresponding Schwinger-Dyson equations within the locally-constant field approximation, we compute the probabilities of nonlinear single Compton scattering and nonlinear Breit-Wheeler pair production by including the effects of the decay of electron, positron, and photon states. As a result, we find that the probabilities of these processes can be expressed as the integral over the light-cone time of the known probabilities valid for stable states per unit of light-cone time times a light-cone time-dependent exponential damping function for each interacting particle. The exponential function for an incoming (outgoing) either electron/positron or photon at each light-cone time corresponds to the total probability that either the electron/positron emits a photon via nonlinear Compton scattering or the photon transforms into an electron-positron pair via nonlinear Breit-Wheeler pair production until that light-cone time (from that light-cone time on). It is interesting that the exponential damping terms depend not only on the particles momentum but also on their spin (for electrons/positrons) and polarization (for photons). This additional dependence on the discrete quantum numbers prevents the application of the electron/positron spin and photon polarization sum-rules, which significantly simplify the computations in the perturbative regime.

    hep-phPRD(2021)·27 citations
15. 15*

    From hydro to jet quenching, coalescence and hadron cascade: a coupled approach to solving the $R_{AA}\otimes v_2$ puzzle

    Wenbin Zhao🇨🇳 · Weiyao Ke🇺🇸 · Wei Chen🇨🇳 · Tan Luo🇪🇸 · Xin-Nian Wang🇨🇳

    Hydrodynamics and jet quenching are responsible for the elliptic flow $v_2$ and suppression of large transverse momentum ($p_T$) hadrons, respectively, two of the most important phenomena leading to the discovery of a strongly coupled quark-gluon plasma (QGP) in high-energy heavy-ion collisions. A consistent description of the hadron suppression factor $R_{AA}$ and $v_2$, especially at intermediate $p_T$, however, remains a challenge. We solve this long-standing $R_{AA}\otimes v_2$ puzzle by including quark coalescence for hadronization and final state hadron cascade in the coupled linear Boltzmann transport-hydro model that combines concurrent jet transport and hydrodynamic evolution of the bulk medium. We illustrate that quark coalescence and hadron cascade, two keys to solving the puzzle, also lead to a splitting of $v_2$ for pions, kaons and protons in the intermediate $p_T$ region. We demonstrate for the first time that experimental data on $R_{AA}$, $v_2$ and their hadron flavor dependence from low to intermediate and high $p_T$ in high-energy heavy-ion collisions can be understood within this coupled framework.

    hep-phnucl-thPRL(2022)·88 citations
16. 16*

    Circular polarisation of gamma rays as a probe of dark matter interactions with cosmic ray electrons

    Marina Cermeño🇧🇪 · Céline Degrande🇧🇪 · Luca Mantani🇧🇪

    Conventional indirect dark matter (DM) searches look for an excess in the electromagnetic emission from the sky that cannot be attributed to known astrophysical sources. Here, we argue that the photon polarisation is an important feature to understand new physics interactions and can be exploited to improve our sensitivity to DM. In particular, circular polarisation can be generated from Beyond the Standard Model interactions if they violate parity and there is an asymmetry in the number of particles which participate in the interaction. In this work, we consider a simplified model for fermionic (Majorana) DM and study the circularly polarised gamma rays below 10 GeV from the scattering of cosmic ray electrons on DM. We calculate the differential flux of positive and negative polarised photons from the Galactic Center and show that the degree of circular polarization can reach up to 90%. Finally, once collider and DM constraints have been taken into account, we estimate the required sensitivity from future experiments to detect this signal finding that, although a distinctive peak will be present in the photon flux spectrum, a near future observation is unlikely. However, different sources or models not considered in this work could provide higher intensity fluxes, leading to a possible detection by e-ASTROGAM. In the event of a discovery, we argue that the polarisation fraction is a valuable characterisation feature of the new sector.

    hep-phastro-ph.HEPhys.Dark Univ.(2021)·5 citations
17. 17*

    Intermediate Mass Black Hole Seeds from Cosmic String Loops

    Robert Brandenberger🇨🇦 · Bryce Cyr🇨🇦 · Hao Jiao (McGill University)🇨🇦

    We demonstrate that cosmic string loops may provide a joint resolution of two mysteries surrounding recently observed black holes. For a string tension in an appropriate range, large radius string loops have the potential to provide the nonlinearities in the early universe which seed supermassive black holes. The more numerous smaller radius string loops can then seed intermediate mass black holes, including those with a mass in the region between 65 and 135 solar masses in which standard black hole formation scenarios predict no black holes are able to form, but which have recently been detected by the LIGO/VIRGO collaboration. We find that there could be as many as $10^6$ of intermediate mass black holes per galaxy, providing a tantalizing target for gravitational wave observatories to look for.

    ↳ astro-ph.COastro-ph.GAgr-qchep-ph+1PRD(2021)·37 citations
18. 18*

    Effective holographic models for QCD: Thermodynamics and viscosity coefficients

    Alfonso Ballon-Bayona🇧🇷 · Luis A. H. Mamani🇧🇷 · Alex S. Miranda🇧🇷 · Vilson T. Zanchin🇧🇷

    A finite temperature extension of the effective holographic models for QCD (EHQCD), proposed in Ref.[1], is investigated in the present work. EHQCD models are characterized by two parameters, the conformal dimension of the relevant operator that deforms the CFT and the associated coupling. We find that black hole solutions appear at temperatures higher than some temperature $T_{min}$ and can be categorized in two classes: large and small black holes. A large black hole is thermally stable and it is therefore interpreted as the gravity dual of a non-conformal plasma. A small black hole, on the other hand, is thermally unstable. We show that thermodynamic quantities such as the entropy density $s$, specific heat $C_V$, and speed of sound $c_s$ are sensitive to the model parameters. We investigate perturbations of the black hole solutions and calculate the viscosity coefficients of the corresponding dual non-conformal plasma. For the shear viscosity, we confirm that the ratio $\eta /s$ is given by the universal result $1/4\pi$. For the bulk viscosity, the ratio $\zeta /s$ varies with the temperature, displaying a rapid growth close to $T_{min}$, and it is sensitive to the model parameters. We compare our results for the thermodynamic quantities with the lattice $SU(N_C)$ results and find that they are compatible as long as the coupling is fixed appropriately as a function of the conformal dimension. We also compare our results for the viscosity coefficients against the JETSCAPE results that are obtained from the analysis of experimental data on heavy ion collisions.

    ↳ hep-thgr-qchep-lathep-phPRD(2021)·22 citations
19. 19*

    Axion-mediated electron-electron interaction in ytterbium monohydroxide molecule

    D.E. Maison🇷🇺 · L.V. Skripnikov🇷🇺 · A.V. Oleynichenko🇷🇺 · A.V. Zaitsevskii🇷🇺

    The YbOH triatomic molecule can be efficiently used to measure the electron electric dipole moment, which violates time-reversal (T) and spatial parity (P) symmetries of fundamental interactions [I. Kozyryev, N.R. Hutzler, Phys. Rev. Lett. 119, 133002 (2017)]. We study another mechanism of the T,P-violation in the YbOH molecule - the electron-electron interaction mediated by the low-mass axiolike particle. For this, we calculate the molecular constant that characterizes this interaction and use it to estimate the expected magnitude of the effect to be measured. It is shown that this molecular constant has the same order of magnitude as the corresponding molecular constant corresponding to the axion-mediated electron-nucleus interaction. According to our estimation, an experiment on YbOH will allow one to set updated laboratory constraints on the CP-violating electron-axion coupling constants.

    ↳ physics.atom-phhep-phphysics.chem-phJ.Chem.Phys.(2021)·14 citations
20. 20*

    Comment on "High Energy Symmetry of String Theory"

    Sheng-Hong Lai🇹🇼 · Jen-Chi Lee🇹🇼 · Yi Yang🇹🇼

    Following the recent discovery of the Lauricella string scattering amplitudes (LSSA) and their associated exact SL(K+3,C) symmetry, we give a brief comment on Gross conjecture regarding "High energy symmetry of string theory".

    ↳ hep-thhep-ph0 citations
21. 21*

    Elvet -- a neural network-based differential equation and variational problem solver

    Jack Y. Araz🇬🇧 · Juan Carlos Criado🇬🇧 · Michael Spannowsky🇬🇧

    We present Elvet, a Python package for solving differential equations and variational problems using machine learning methods. Elvet can deal with any system of coupled ordinary or partial differential equations with arbitrary initial and boundary conditions. It can also minimize any functional that depends on a collection of functions of several variables while imposing constraints on them. The solution to any of these problems is represented as a neural network trained to produce the desired function.

    ↳ cs.LGhep-lathep-phhep-th+113 citations
22. 22*

    Local polarization and isothermal local equilibrium in relativistic heavy ion collisions

    F. Becattini (U. Florence)🇮🇹 · M. Buzzegoli (U. Florence)🇮🇹 · G. Inghirami (GSI, Darmstadt)🇩🇪 · I. Karpenko (U. Prague)🇨🇿 · A. Palermo (U. Florence)🇮🇹

    We show that the inclusion of a recently found additional term of the spin polarization vector at local equilibrium which is linear in the symmetrized gradients of the velocity field, and the assumption of hadron production at constant temperature restore the quantitative agreement between hydrodynamic model predictions and local polarization measurements in relativistic heavy ion collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV. The longitudinal component of the spin polarization vector turns out to be very sensitive to the temperature value, with a good fit around 155 MeV. The implications of this finding are discussed.

    ↳ nucl-thhep-phPRL(2021)·239 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.