Fri·Oct 30, 2020Friday·October 30, 2020

1. 01*

   An Evaluation of The Proton Structure Functions $F_2$ and $F_L$ at Small $x$

   G.R.Boroun🇮🇷 · B.Rezaei🇮🇷

   We describe the determination of the DIS structure functions $F_2$ and $F_L$ by using the singlet Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) and Altarelli-Martinelli equations at small values of $x$. The determination of the longitudinal structure function is presented as a parameterization of $F_2(x,Q^2)$ and its derivative. Analytical expressions for ${\sigma }_r(x,Q^2)$ in terms of the effective parameters of the parameterization of $F_2(x,Q^2)$ and $F_L(x,Q^2)$ are presented. This analysis is enriched by including the higher-twist effects in calculation of the reduced cross sections which is important at low-$x$ and low-$Q^2$ regions. Numerical calculations and comparison with H1 data demonstrate that the suggested method provides reliable $F_L(x,Q^2)$ and ${\sigma }_r(x,Q^2)$ at low $x$ in a wide range of the low absolute four-momentum transfers squared ($1.5{\mathrm{GeV}}^2<Q^2<120{\mathrm{GeV}}^2$) at moderate and high inelasticity. Expanding the method to low and ultra low values of $x$ can be considered in the process analysis of new colliders. We compare the obtained longitudinal structure function with respect to the LHeC simulated uncertainties [CERN-ACC-Note-2020-0002, arXiv:2007.14491 [hep-ex] (2020)] with the results from CT18 [Phys.Rev.D{\bf103}, 014013(2021)] parametrization model.

   hep-phPLB(2021)·20 citations
2. 02*

   Flavored multiscalar ${\mathbf{S}}_3$ model with normal hierarchy neutrino mass

   J. D. García-Aguilar🇲🇽 · Juan Carlos Gómez-Izquierdo🇲🇽

   We construct a multiscalar and non-renormalizable model where the ${\mathbf{S}}_3$ flavor symmetry drives mainly the Yukawa couplings. In the quark sector, the Nearest Neighbor Interaction (NNI) textures are behind the CKM mixing matrix so that this is fitted in good agreement with the last available results. In the lepton sector, an almost diagonal charged lepton mass matrix and extended Fritzsch mass textures in the effective neutrino mass matrix, that comes from the type II see-saw mechanism, provide consistent values for the mixing angles where the normal hierarchy is favored. The model predicts a CP-violating phase consistent with the experimental data and the BR for the lepton flavor violation process, $\mu \to e\gamma$, is well below the current bound.

   hep-ph3 citations
3. 03*

   Can $\Omega (2012)$ be explained as a molecular state?

   Xuejie Liu🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳 · Dianyong Chen🇨🇳

   We conduct a dynamical calculation of pentaquark systems with quark contents $sssu\bar{u}$ in the framework of two quark models: the chiral quark model(ChQM) and quark delocalization color screening model(QDCSM). The effective potentials between baryon and meson clusters are given, and the possible bound states are also investigated. Besides, the study of the scattering process of the open channels is also performed to look for any resonance state. The results show that the $\Omega (2012)$ is not suitable for the interpretation as a ${\Xi }^{\ast }\bar{K}$ molecular state in present quark models. Two resonance states: the ${\Xi }^{\ast }{\bar{K}}^{\ast }$ with $I{J}^P=0{\frac{3}{2}}^{-}$ ($M=2328\sim 2374$ MeV, $\Gamma =57\sim 65.5$ MeV) and $I{J}^P=1{\frac{3}{2}}^{-}$ ($M=2341\sim 2386$ MeV, $\Gamma =31.5\sim 100$ MeV) are obtained in both QDCSM and ChQM, which indicates that both of these two states are more possible to be existed and worthy of being searched by future experiments.

   hep-phPRC(2021)·27 citations
4. 04*

   No-go limitations on UV completions of the Neutrino Option

   Ilaria Brivio🇩🇪 · Jim Talbert🇩🇰 · Michael Trott🇩🇰

   We discuss the possible origin of the Majorana mass scale(s) required for the "Neutrino Option" where the electroweak scale is generated simultaneously with light neutrino masses in a type-I seesaw model, by common dimension four interactions. We establish no-go constraints on the perturbative generation of the Majorana masses required due to global symmetries of the seesaw Lagrangian.

   hep-phPRD(2021)·5 citations
5. 05*

   Total cross sections of $e\gamma \to eX\bar{X}$ processes with $X=\mu ,\gamma ,e$ via multiloop methods

   Roman N. Lee🇷🇺 · Alexey A. Lyubyakin🇷🇺 · Vyacheslav A. Stotsky🇷🇺

   Using modern multiloop calculation methods, we derive the analytical expressions for the total cross sections of the processes $e^{-}\gamma \to e^{-}X\bar{X}$ with $X=\mu ,\gamma$ or $e$ at arbitrary energies. For the first two processes our results are expressed via classical polylogarithms. The cross section of $e^{-}\gamma \to e^{-}{e}^{-}{e}^{+}$ is represented as a one-fold integral of complete elliptic integral $\mathrm{K}$ and logarithms. Using our results, we calculate the threshold and high-energy asymptotics and compare them with available results.

   hep-phJHEP(2021)·10 citations
6. 06*

   Analysis of the $\mathbf{\gamma \gamma }\to \mathbf{D}\bar{\mathbf{D}}$ reaction and the $D\bar{D}$ bound state

   En Wang🇨🇳 · Hong-Shen Li🇨🇳 · Wei-Hong Liang🇨🇳 · Eulogio Oset🇪🇸

   In this work, we investigate the reaction of $\gamma \gamma \to D\bar{D}$, taking into account the s-wave $D\bar{D}$ final state interaction. By fitting to the $D\bar{D}$ invariant mass distributions measured by the Belle and BaBar Collaborations, we obtain a good reproduction of the data by means of a $D\bar{D}$ amplitude that produces a bound $D\bar{D}$ state with $I=0$ close to threshold. The error bands of the fits indicate, however, that more precise data on this reaction are needed to be more assertive about the position and width of such state.

   hep-phPRD(2021)·41 citations
7. 07*

   Nuclear scattering configurations of onia in different frames

   Anh Dung Le🇫🇷 · Alfred H. Mueller🇺🇸 · Stéphane Munier🇫🇷

   In the scattering of a small onium off a large nucleus at high center-of-mass energies, when the parameters are set in such a way that the cross section at fixed impact parameter is small, events are triggered by rare partonic fluctuations of the onium, which are very deformed with respect to typical configurations. Using the color dipole picture of high-energy interactions in quantum chromodynamics, in which the quantum states of the onium are represented by sets of dipoles generated by a branching process, we describe the typical scattering configurations as seen from different reference frames, from the restframe of the nucleus to frames in which the rapidity is shared between the projectile onium and the nucleus. We show that taking advantage of the freedom to select a frame in the latter class makes possible to derive complete asymptotic expressions for some boost-invariant quantities, beyond the total cross section, from a procedure which leverages the limited available knowledge on the properties of the solutions to the Balitsky-Kovchegov equation that governs the rapidity-dependence of total cross sections. We obtain in this way an analytic expression for the rapidity-distribution of the first branching of the slowest parent dipole of the set of those which scatter. This distribution provides an estimator of the correlations of the interacting dipoles, and is also known to be related to the rapidity-gap distribution in diffractive dissociation, an observable measurable at a future electron-ion collider. Furthermore, our result may be formulated as a more general conjecture, that we expect to hold true for any one-dimensional branching random walk model, on the branching time of the most recent common ancestor of all the particles that end up to the right of a given position.

   hep-phcond-mat.stat-mechPRD(2021)·4 citations
8. 08*

   MUMUG: a fast Monte Carlo generator for radiative muon pair production (a pedagogical tutorial)

   Z.K. Silagadze🇷🇺

   A fast leading-order Monte Carlo generator for the process $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}\gamma$ is described. In fact, using the $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}\gamma$ process as an example, we provide a pedagogical demonstration of how a Monte Carlo generator can be created from scratch. The $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}\gamma$ process was chosen, since in this case we are not faced with either too trivial or too difficult a task. Matrix elements are calculated using the helicity amplitude method. Monte Carlo algorithm uses the acceptance-rejection method with an appropriately chosen simplified distribution that can be generated using an efficient algorithm. We provide a detailed pedagogical exposition of both the helicity amplitude method and the Monte Carlo technique, which we hope will be useful for high energy physics students.

   hep-phhep-exEur.Phys.J.Plus(2021)·0 citations
9. 09*

   Superselection of the weak hypercharge and the algebra of the Standard Model

   Ivan Todorov🇧🇬

   Restricting the ${\mathbb{Z}}_2$-graded tensor product of Clifford algebras $C{\ell }_4\hat{\otimes }C{\ell }_6$ to the particle subspace allows a natural definition of the Higgs field $\Phi$, the scalar part of Quillen's superconnection, as an element of $C{\ell }_4^1$. We emphasize the role of the exactly conserved weak hypercharge Y, promoted here to a superselection rule for both observables and gauge transformations. This yields a change of the definition of the particle subspace adopted in recent work with Michel Dubois-Violette \cite{DT20}; here we exclude the zero eigensubspace of Y consisting of the sterile (anti)neutrinos which are allowed to mix. One thus modifies the Lie superalgebra generated by the Higgs field. Equating the normalizations of $\Phi$ in the lepton and the quark subalgebras we obtain a relation between the masses of the W boson and the Higgs that fits the experimental values within one percent accuracy.

   hep-phhep-thJHEP(2021)·9 citations
10. 10*

    Efficient computation of two-loop amplitudes for Higgs boson pair production

    Guoxing Wang🇨🇳 · Yuxuan Wang🇨🇳 · Xiaofeng Xu🇨🇭 · Yongqi Xu🇨🇳 · Li Lin Yang🇨🇳

    We present a precise and efficient computation of the two-loop amplitudes entering the Higgs boson pair production process via gluon fusion. Our approach is based on the small-Higgs-mass expansion while keeping the full dependence on the top quark mass and other kinematic invariants. We compare our results to the up-to-date predictions based on a combination of sector decomposition and high-energy expansion. We find that our method provides precision numeric predictions in the entire phase space, while at the same time is highly efficient as the computation can be easily performed on a normal desktop or laptop computer. Our method is valuable for practical phenomenological studies of the Higgs boson pair production process, and can also be applied to other similar processes.

    hep-phPRD(2021)·29 citations
11. 11*

    Shear viscosity in QCD and why it's hard to calculate

    Guy D. Moore🇩🇪

    Shear viscosity is a dynamical property of fluid systems close to equilibrium, describing resistance to sheared flow. After reviewing the physics of viscosity and the reason it is usually difficult to compute, I discuss its importance within the theory of QCD and the obstacles to carrying out such a computation. A diagrammatic analysis requires extensive resummations and even then convergence is poor at physically relevant couplings. Lattice approaches require a poorly controlled analytical continuation of data from the Euclidean to the Minkowski domain. At present our best results for QCD shear viscosity come from the hydrodynamical interpretations of experiments, with first-principles calculations trailing behind.

    hep-phActa Phys.Polon.Supp.(2021)·21 citations
12. 12*

    Vacuum structure and electroweak phase transition in singlet scalar dark matter

    Parsa Ghorbani🇮🇹

    In the presence of a real singlet scalar field with ${\mathbb{Z}}_2$ symmetry in addition to the Higgs field in the Standard Model, we analytically investigate all possible one-step and two-step electroweak phase transitions (EWPT) in the high-temperature expansion limit. In particular, we examine the possibility of a first-order phase transition in an intermediate temperature interval of the universe for two-step scenarios. In all scenarios, we provide with necessary conditions on the parameters of the model to address a first- or second-order phase transition if ever possible in the high-temperature approximation. We show that among all possible EWPT channels in this model, only the two-step phase transition $(0,0)\to (0,w)\to (v,0)$ can be of first-order type, either in the first or second step. The conditions obtained for EWPT is confronted with the dark matter (DM) and collider constraints. It is shown that the second-order one-step $(0,0)\to (v,0)$ scenario can evade the DM constraints, but it is not accessible to future colliders. The two-step first-order EWPT scenario $(0,0)\to (0,w)\to (v,0)$, except for small DM masses, is excluded by direct detection experiments XENON1T/LUX, but it is accessible in future colliders ILC/TLEP.

    hep-phPhys.Dark Univ.(2021)·23 citations
13. 13*

    Axionlike particles searches in reactor experiments

    D. Aristizabal Sierra🇨🇱 · V. De Romeri🇪🇸 · L. J. Flores🇲🇽 · D.K. Papoulias🇬🇷

    Reactor neutrino experiments provide a rich environment for the study of axionlike particles (ALPs). Using the intense photon flux produced in the nuclear reactor core, these experiments have the potential to probe ALPs with masses below 10 MeV. We explore the feasibility of these searches by considering ALPs produced through Primakoff and Compton-like processes as well as nuclear transitions. These particles can subsequently interact with the material of a nearby detector via inverse Primakoff and inverse Compton-like scatterings, via axio-electric absorption, or they can decay into photon or electron-positron pairs. We demonstrate that reactor-based neutrino experiments have a high potential to test ALP-photon couplings and masses, currently probed only by cosmological and astrophysical observations, thus providing complementary laboratory-based searches. We furthermore show how reactor facilities will be able to test previously unexplored regions in the $\sim$MeV ALP mass range and ALP-electron couplings of the order of $g_{aee}\sim 10^{-8}$ as well as ALP-nucleon couplings of the order of $g_{ann}^{(1)}\sim 10^{-9}$, testing regions beyond TEXONO and Borexino limits.

    hep-phhep-exnucl-exJHEP(2021)·57 citations
14. 14*

    Non-Hermitian Yukawa interactions of fermions with axions: potential microscopic origin and dynamical mass generation

    Nick E. Mavromatos (King's College London)🇬🇧

    In this mini review, we discuss some recent developments regarding properties of (quantum) field-theory models containing anti-Hermitian Yukawa interactions between pseudoscalar fields (axions) and Dirac (or Majorana) fermions. Specifically, after motivating physically such interactions, in the context of string-inspired low-energy effective field theories, involving right-handed neutrinos and axion fields, we proceed to discuss their formal consistency within the so-called Parity-Time-reversal(PT)-symmetry framework, as well as dynamical mass generation, induced by the Yukawa interactions, for both fermions and axions. The Yukawa couplings are assumed weak, given that they are conjectured to have been generated by non-perturbative effects in the underlying microscopic string theory. The models under discussion contain, in addition to the Yukawa terms, also anti-Hermitian anomalous derivative couplings of the pseudoscalar fields to axial fermion currents, as well as interactions of the fermions with non-Hermitian axial backgrounds. We discuss the role of such additional couplings on the Yukawa-induced dynamically-generated masses. For the case where the fermions are right-handed neutrinos, we compare such masses with the radiative ones induced by both, the anti-Hermitian anomalous terms and the anti-Hermitian Yukawa interactions in phenomenologically relevant models.

    hep-phhep-thJ.Phys.Conf.Ser.·9 citations
15. 15*

    Renormalization Group Improvement of the Effective Potential: an EFT Approach

    Aneesh V. Manohar🇺🇸 · Emily Nardoni🇺🇸

    We apply effective field theory (EFT) methods to compute the renormalization group improved effective potential for theories with a large mass hierarchy. Our method allows one to compute the effective potential in a systematic expansion in powers of the mass ratio, as well as to sum large logarithms of mass ratios using renormalization group evolution. The effective potential is the sum of one-particle irreducible diagrams (1PI) but information about which diagrams are 1PI is lost after matching to the EFT, since heavy lines get shrunk to a point. We therefore introduce a tadpole condition in place of the 1PI condition, and use the renormalization group improved value of the tadpole in computing the effective potential. We explain why the effective potential computed using an EFT is not the same as the effective potential of the EFT. We illustrate our method using the $O(N)$ model, a theory of two scalars in the unbroken and broken phases, and the Higgs-Yukawa model. Our leading-log result, obtained by integrating the one-loop $\beta$-functions, correctly reproduces the log-squared term in explicit two-loop calculations. Our method does not have a Goldstone boson infrared divergence problem.

    hep-phhep-thJHEP(2021)·28 citations
16. 16*

    Leading-Color Two-Loop QCD Corrections for Three-Photon Production at Hadron Colliders

    S. Abreu🇨🇭 · B. Page🇫🇷 · E. Pascual🇩🇪 · V. Sotnikov🇩🇪

    We compute the two-loop helicity amplitudes for the production of three photons at hadron colliders in QCD at leading-color. Using the two-loop numerical unitarity method coupled with analytic reconstruction techniques, we obtain the decomposition of the two-loop amplitudes in terms of master integrals in analytic form. These expressions are valid to all orders in the dimensional regulator. We use them to compute the two-loop finite remainders, which are given in a form that can be efficiently evaluated across the whole physical phase space. We further package these results in a public code which assembles the helicity-summed squared two-loop remainders, whose numerical stability across phase-space is demonstrated. This is the first time that a five-point two-loop process is publicly available for immediate phenomenological applications.

    hep-phJHEP(2021)·73 citations
17. 17*

    Radio-frequency Dark Photon Dark Matter across the Sun

    Haipeng An🇨🇳 · Fa Peng Huang🇺🇸 · Jia Liu🇨🇳 · Wei Xue🇺🇸

    Dark photon as an ultralight dark matter candidate can interact with the Standard Model particles via kinetic mixing. We propose to search for the ultralight dark photon dark matter using radio telescopes with solar observations. The dark photon dark matter can efficiently convert into photons in the outermost region of the solar atmosphere, the solar corona, where the plasma mass of photons is close to the dark photon rest mass. Due to the strong resonant conversion and benefiting from the short distance between the Sun and the Earth, the radio telescopes can lead the dark photon search sensitivity in the mass range of $4\times 10^{-8}-4\times 10^{-6}\mathrm{eV}$, corresponding to the frequency $10-1000\mathrm{MHz}$. As a promising example, the operating radio telescope LOFAR can reach the kinetic mixing $ϵ\sim 10^{-13}$ ($10^{-14}$) within 1 (100) hour solar observations. The future experiment SKA phase 1 can reach $ϵ\sim 10^{-16}-10^{-14}$ with $1$ hour solar observations.

    hep-phastro-ph.SRPRL(2021)·46 citations
18. 18*

    Selective enhancement of the QCD axion couplings

    Luc Darmé🇮🇹 · Luca Di Luzio🇩🇪 · Maurizio Giannotti🇺🇸 · Enrico Nardi🇮🇹

    We present a mechanism wherein the QCD axion coupling to nucleons, photons, or electrons, can be enhanced selectively without increasing the axion mass. We focus in particular on the axion-nucleon couplings, that are generally considered to be largely model-independent, and we show how nucleophilic axion models can be constructed. We discuss the implications of a nucleophilic axion for astrophysics, cosmology and laboratory searches. We present a model with enhanced axion couplings to nucleons and photons that can provide an excellent fit to the anomalous emission of hard X-rays recently observed from a group of nearby neutron stars, and we argue that such a scenario can be thoroughly tested in forthcoming axion-search experiments.

    hep-phastro-ph.COastro-ph.GAastro-ph.HE+1PRD(2021)·36 citations
19. 19*

    Axion string signatures II: A cosmological plasma collider

    Prateek Agrawal🇬🇧 · Anson Hook🇺🇸 · Junwu Huang🇨🇦 · Gustavo Marques-Tavares🇺🇸

    We study early and late time signatures of both QCD axion strings and hyperlight axion strings (axiverse strings). We focus on charge deposition onto axion strings from electromagnetic fields and subsequent novel neutralizing mechanisms due to bound state formation. While early universe signatures appear unlikely, there are a plethora of late time signatures. Axion strings passing through galaxies obtain a huge charge density, which is neutralized by a dense plasma of bound state Standard Model particles forming a one dimensional "atom". The charged wave packets on the string, as well as the dense plasma outside, travel at nearly the speed of light along the string. These packets of high energy plasma collide with a center of mass energy of up to $10^9$ GeV. These collisions can have luminosities up to seven orders of magnitude larger than the solar luminosity, and last for thousands of years, making them visible at radio telescopes even when they occur cosmologically far away. The new observables are complementary to the CMB observables for hyperlight axion strings that have been recently proposed, and are sensitive to a similar motivated parameter range.

    hep-phastro-ph.COastro-ph.HEhep-thJHEP(2022)·36 citations
20. 20*

    The Feynman rules for the SMEFT in the background field gauge

    T. Corbett🇩🇰

    We present a package for FeynRules which derives the Feynman rules for the Standard Model Effective Field Theory up to dimension-six using the background field method for gauge fixing. The package includes operators which shift the kinetic and mass terms of the Lagrangian up to dimension-eight and including dimension-six squared effects consistently. To the best of the author's knowledge this is the first publicly available package to include dimension-six squared effects consistently. The package is validated in a partner publication by analyzing the Ward Identities at dimension-six and one-loop order. We also extend the partner work in this article by including the dimension-six squared effects further demonstrating the consistency of their implementation. In doing so we find that failure to consistently include field shifts to dimension-six squared causes a breakdown in the Ward identities implying concerns about many calculations in the literature which do not properly incorporate these effects. The FeynRules files, as well as Mathematica notebooks performing the relevant calculations, can be downloaded from the FeynRules website and are included as ancillary files to this publication.

    hep-phJHEP(2021)·28 citations
21. 21*

    Constraining primordial black holes as dark matter at JUNO

    Sai Wang🇨🇳 · Dong-Mei Xia🇨🇳 · Xukun Zhang🇨🇳 · Shun Zhou🇨🇳 · Zhe Chang🇨🇳

    As an attractive candidate for dark matter, the primordial black holes (PBHs) in the mass range ($10^{15}\sim 10^{16}$)$\mathrm{g}$ could be detected via their Hawking radiation, including neutrinos and antineutrinos of three flavors. In this paper, we investigate the possibility to constrain the PBH as dark matter by measuring (anti)neutrino signals at the large liquid-scintillator detector of Jiangmen Underground Neutrino Observatory (JUNO). Among six available detection channels, the inverse beta decay ${\overline{\nu }}_e^{}+p\to e^{+}+n$ is shown to be most sensitive to the fraction $f_{\mathrm{PBH}}^{}$ of PBHs contributing to the dark matter abundance. Given the PBH mass $M_{\mathrm{PBH}}^{}=10^{15}\mathrm{g}$, we find that JUNO will be able to place an upper bound $f_{\mathrm{PBH}}^{}\lesssim 3\times 10^{-5}$, which is 20 times better than the current best limit $f_{\mathrm{PBH}}^{}\lesssim 6\times 10^{-4}$ from Super-Kamiokande. For heavier PBHs with a lower Hawking temperature, the (anti)neutrinos become less energetic, leading to a relatively weaker bound.

    hep-phastro-ph.COgr-qchep-thPRD(2021)·61 citations
22. 22*

    Fluctuation and dissipation within a deformed holographic model with backreaction

    Nathan G. Caldeira🇧🇷 · Eduardo Folco Capossoli🇧🇷 · Carlos A. D. Zarro🇧🇷 · Henrique Boschi-Filho🇧🇷

    In this work we study the fluctuation and dissipation of a string attached to a brane in a deformed and backreated AdS-Schwarzschild spacetime. This space is a solution of Einstein-dilaton equations and contains a conformal exponential factor $\exp (k/r^2)$ in the metric. We consider the backreaction contributions coming only from the exponential warp factor on the AdS-Schwarzschild black hole, where the string and brane are in the probe approximation. Within this Lorentz invariant holographic model we have computed the admittance, the diffusion coefficient, the two-point functions and the regularized mean square displacement $s_{reg}^2$. From this quantity we obtain the diffuse and ballistic regimes characteristic of the Brownian motion. From the two-point functions and the admittance, we also have checked the well know fluctuation-dissipation theorem in this set up.

    ↳ hep-thhep-phPLB(2021)·10 citations
23. 23*

    Search for lepton-number- and baryon-number-violating tau decays at Belle

    D. Sahoo🇮🇳 · G. B. Mohanty🇮🇳 · K. Trabelsi🇫🇷 · I. Adachi🇯🇵 · K. Adamczyk🇵🇱 · H. Aihara🇯🇵 · S. Al Said🇸🇦 · D. M. Asner🇺🇸 · T. Aushev🇷🇺 · R. Ayad🇸🇦 · T. Aziz🇮🇳 · V. Babu🇩🇪 and 213 other authors

    We search for lepton-number- and baryon-number-violating decays ${\tau }^{-}\to \overline{p}{e}^{+}{e}^{-}$, $p{e}^{-}{e}^{-}$, $\overline{p}{e}^{+}{\mu }^{-}$, $\overline{p}{e}^{-}{\mu }^{+}$, $\overline{p}{\mu }^{+}{\mu }^{-}$, and $p{\mu }^{-}{\mu }^{-}$ using 921 fb${}^{-1}$ of data, equivalent to $(841\pm 12)\times 10^6$ ${\tau }^{+}{\tau }^{-}$ events, recorded with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. In the absence of a signal, $90\%$ confidence-level upper limits are set on the branching fractions of these decays in the range $(1.8$-$4.0)\times 10^{-8}$. We set the world's first limits on the first four channels and improve the existing limits by an order of magnitude for the last two channels.

    ↳ hep-exhep-phPRD(2020)·19 citations
24. 24*

    Higher order cumulants of electric charge and strangeness fluctuations on the crossover line

    D. Bollweg🇩🇪 · J. Goswami🇩🇪 · F. Karsch🇩🇪 · S. Mukherjee🇺🇸 · C. Schmidt🇩🇪

    We present lattice QCD calculations of higher order cumulants of electric charge distributions for small baryon chemical potentials ${\mu }_B$ by using up to NNNLO Taylor expansions. Ratios of these cumulants are evaluated on the pseudo-critical line, $T_{pc}({\mu }_B)$, of the chiral transition and compared to corresponding measurements in heavy ion collision experiments by the STAR and PHENIX Collaborations. We demonstrate that these comparisons give strong constraints on freeze-out parameters. Furthermore, we use strangeness fluctuation observables to compute the ratio ${\mu }_S/{\mu }_B$ on the crossover line and compare it to ${\mu }_S/{\mu }_B$ at freeze-out stemming from fits to strange baryon yields measured by the STAR Collaboration.

    ↳ hep-lathep-phnucl-thActa Phys.Polon.B(2021)·3 citations
25. 25*

    Overview of the QCD phase diagram -- Recent progress from the lattice

    Jana N. Guenther🇫🇷

    In recent years there has been much progress on the investigation of the QCD phase diagram with lattice QCD simulations. In this review I focus on the developments in the last two years. Especially the addition of external influences or new parameter ranges yield an increasing number of interesting results. I discuss the progress for small, finite densities from both analytical continuation and Complex Langevin simulations, for heavy quark bound states (quarkonium), the dependence on the quark masses (Columbia plot) and the influence of a magnetic field. Many of these conditions are relevant for the understanding of both the QCD transition in the early universe and heavy ion collision experiments which are conducted for example at the LHC and RHIC.

    ↳ hep-lathep-phEPJA(2021)·170 citations
26. 26*

    How do I introduce Schrödinger equation during the quantum mechanics course?

    T. Mart🇮🇩

    In this paper I explain how I usually introduce the Schrödinger equation during the quantum mechanics course. My preferred method is the chronological one. Since the Schrödinger equation belongs to a special case of wave equations I start the course with introducing the wave equation. The Schrödinger equation is derived with the help of the two quantum concepts introduced by Max Planck, Einstein, and de Broglie, i.e., the energy of a photon $E=\hslash \omega$ and the wavelength of the de Broglie wave $\lambda =h/p$. Finally, the difference between the classical wave equation and the quantum Schrödinger one is explained in order to help the students to grasp the meaning of quantum wavefunction $\Psi (\mathbf{r},t)$. A comparison of the present method to the approaches given by the authors of quantum mechanics textbooks as well as that of the original Nuffield A level is presented. It is found that the present approach is different from those given by these authors, except by Weinberg or Dicke and Wittke. However, the approach is in line with the original Nuffield A level one.

    ↳ physics.ed-phhep-phnucl-thquant-phPhys.Educ.(2021)·1 citation
27. 27*

    Universal scaling properties of QCD close to the chiral limit

    Olaf Kaczmarek🇩🇪 · Frithjof Karsch🇩🇪 · Anirban Lahiri🇩🇪 · Christian Schmidt🇩🇪

    We present a lattice QCD based determination of the chiral phase transition temperature in QCD with two massless (up and down) and one strange quark having its physical mass. We propose and calculate two novel estimators for the chiral transition temperature for several values of the light quark masses, corresponding to Goldstone pion masses in the range of $58\mathrm{MeV}\lesssim m_{\pi }\lesssim 163\mathrm{MeV}$. The chiral phase transition temperature is determined by extrapolating to vanishing pion mass using universal scaling relations. After thermodynamic, continuum and chiral extrapolations we find the chiral phase transition temperature $T_c^0=132_{-6}^{+3}$ MeV. We also show some preliminary calculations that use the conventional estimator for the pseudo-critical temperature and compare with the new estimators for $T_c^0$. Furthermore, we show results for the ratio of the chiral order parameter and its susceptibility and argue that this ratio can be used to differentiate between $O(N)$ and $Z_2$ universality classes in a non-parametric manner.

    ↳ hep-lathep-phnucl-thActa Phys.Polon.Supp.(2021)·9 citations
28. 28*

    Gouy phase of type-I SPDC-generated biphotons

    F. C. V. de Brito🇧🇷 · I. G. da Paz🇧🇷 · Brigitte Hiller🇵🇹 · Jonas B. Araujo🇧🇷 · Marcos Sampaio🇧🇷

    We consider a double Gaussian approximation to describe the wavefunction of twin photons (also called a biphoton) created in a nonlinear crystal via a type-I spontaneous parametric downconversion (SPDC) process. We find that the wavefunction develops a Gouy phase while it propagates, being dependent of the two-photon correlation through the Rayleigh length. We evaluate the covariance matrix and show that the logarithmic negativity, useful in quantifying entanglement in Gaussian states, although Rayleigh-dependent, does not depend on the propagation distance. In addition, we show that the two-photon entanglement can be connected to the biphoton Gouy phase as these quantities are Rayleigh-length-related. Then, we focus the double Gaussian biphoton wavefunction using a thin lens and calculate a Gouy phase that is in reasonable agreement with the experimental data of D. Kawase et al. published in Ref. [1].

    ↳ quant-phhep-phPLA(2021)·7 citations
29. 29*

    Inflation inside non-topological defects and scalar black holes

    Y. Brihaye🇧🇪 · F. Cônsole🇧🇷 · B. Hartmann🇧🇷

    In this paper, we demonstrate that a phenomenon described as "topological inflation" during which inflation occurs inside the core of topological defects, has a non-topological counterpart. This appears in a simple set-up containing Einstein gravity coupled minimally to an electromagnetic field as well as a self-interacting, complex valued scalar field. The U(1) symmetry of the model is unbroken and leads to the existence of globally regular solutions, so-called boson stars, that develop a horizon for sufficiently strong gravitational coupling. We also find that the same phenomenon exists for black holes with scalar hair.

    ↳ gr-qchep-phhep-thSymmetry(2020)·10 citations
30. 30*

    Glueballs and Strings in $Sp(2N)$ Yang-Mills theories

    Ed Bennett🇬🇧 · Jack Holligan🇬🇧 · Deog Ki Hong🇰🇷 · Jong-Wan Lee🇰🇷 · C.-J. David Lin🇹🇼 · Biagio Lucini🇬🇧 · Maurizio Piai🇬🇧 · Davide Vadacchino🇮🇹

    Motivated in part by the pseudo-Nambu Goldstone Boson mechanism of electroweak symmetry breaking in Composite Higgs Models, in part by dark matter scenarios with strongly coupled origin, as well as by general theoretical considerations related to the large-N extrapolation, we perform lattice studies of the Yang-Mills theories with $Sp(2N)$ gauge groups. We measure the string tension and the mass spectrum of glueballs, extracted from appropriate 2-point correlation functions of operators organised as irreducible representations of the octahedral symmetry group. We perform the continuum extrapolation and study the magnitude of finite-size effects, showing that they are negligible in our calculation. We present new numerical results for $N=1$, $2$, $3$, $4$, combine them with data previously obtained for $N=2$, and extrapolate towards $N\to \infty$. We confirm explicitly the expectation that, as already known for $N=1,2$ also for $N=3,4$ a confining potential rising linearly with the distance binds a static quark to its antiquark. We compare our results to the existing literature on other gauge groups, with particular attention devoted to the large-$N$ limit. We find agreement with the known values of the mass of the $0^{++}$, $0^{++\ast }$ and $2^{++}$ glueballs obtained taking the large-$N$ limit in the $SU(N)$ groups. In addition, we determine for the first time the mass of some heavier glueball states at finite $N$ in $Sp(2N)$ and extrapolate the results towards $N\to +\infty$ taking the limit in the latter groups. Since the large-$N$ limit of $Sp(2N)$ is the same as in $SU(N)$, our results are relevant also for the study of QCD-like theories.

    ↳ hep-lathep-phhep-thPRD(2021)·55 citations
31. 31*

    Quintessential $\alpha$-attractor inflation: forecasts for Stage IV galaxy surveys

    Yashar Akrami🇫🇷 · Santiago Casas🇫🇷 · Senwen Deng🇫🇷 · Valeri Vardanyan🇯🇵

    Single-field models of $\alpha$-attractor quintessential inflation provide a unified picture of the two periods of early- and late-time cosmic acceleration, where both inflation and dark energy are described by a single scalar degree of freedom rolling down a runaway potential. These theoretically well-motivated models have distinct observational predictions that are in agreement with existing cosmological data. We show that the next generation of large-scale structure surveys, even when no other cosmological data sets are considered, will strongly constrain the parameter space of these models, and test them against the standard cosmological model and more conventional non-quintessential inflation. In particular, we expect $\mathcal{O}(10^{-5}-10^{-4})$ constraints on the present values of the dark energy equation of state and its time derivative, $w_0$ and $w_a$. We also forecast more than one order of magnitude tighter constraints on the spectral index of primordial curvature perturbations $n_s$ compared to the expectations for the standard model. This demonstrates the powerful synergy between the upcoming large-scale structure probes of inflation and those aiming to measure the tensor-to-scalar ratio $r$ through the observation of $B$-mode polarization of the cosmic microwave background.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2021)·35 citations
32. 32*

    Sensitivity of the Polyakov loop to chiral symmetry restoration

    David Anthony Clarke🇩🇪 · Olaf Kaczmarek🇩🇪 · Anirban Lahiri🇩🇪 · Mugdha Sarkar🇩🇪

    In the heavy, static quark mass regime of QCD, the Polyakov loop is well known to be an order parameter of the deconfinement phase transition; however, the sensitivity of the Polyakov loop to the deconfinement of light, dynamical quarks is less clear. On the other hand, from the perspective of an effective Lagrangian written in the vicinity of the chiral transition, the Polyakov loop is an energy-like operator and should hence scale as any energy-like operator would. We show here that the Polyakov loop and heavy-quark free energy are sensitive to the chiral transition, i.e. their scaling is consistent with energy-like observables in 3-$d$ $O(N)$ universality classes.

    ↳ hep-lathep-phnucl-thActa Phys.Polon.Supp.(2021)·5 citations
33. 33*

    GroupMath: A Mathematica package for group theory calculations

    Renato M. Fonseca🇨🇿

    GroupMath is a Mathematica package which performs several calculations related to semi-simple Lie algebras and the permutation groups, both of which are important in particle physics as well as in other areas of research.

    ↳ hep-thhep-phComput.Phys.Commun.(2021)·84 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.