Tue·Jun 8, 2021Tuesday·June 8, 2021

1. 01*

   Spacetime evolution of lepton number densities and wave packet-like effects for neutrino flavor and chiral oscillations in quantum field theory

   Apriadi Salim Adam🇮🇩 · Nicholas J. Benoit🇯🇵 · Yuta Kawamura🇯🇵 · Yamato Matsuo🇯🇵 · Takuya Morozumi🇯🇵 · Yusuke Shimizu🇯🇵 · Naoya Toyota🇯🇵

   We present a formulation of lepton family numbers, based on quantum field theory, for neutrino oscillation phenomenology that can be applied to nonrelativistic and relativistic energies for neutrinos. It is formulated for both types of neutrinos, Dirac and Majorana. The formulation is constructed as the time evolution of a lepton family number density operator. Then, the time evolution of the lepton family number density operator becomes dependent on the mass and new features appear. The expectation value of the density operator is evaluated for the initial state with a Gaussian distribution for the momentum amplitude. This enables us to study wave packet-like decoherence effects. We show in the nonrelativistic regime, the type of neutrino mass are distinguishable even under the presence of wave packet-like decoherence effects.

   hep-phPRD(2023)·5 citations
2. 02*

   Heavy flavor pentaquarks with four heavy quarks

   Hong-Tao An🇨🇳 · Kan Chen🇨🇳 · Zhan-Wei Liu🇨🇳 · Xiang Liu🇨🇳

   In this work, we carry out the study of heavy flavor pentatuarks with four heavy quarks, which have typical $QQQQ\bar{q}$ configuration. Within the Chromomagnetic Interaction model, the mass spectrum of these discussed $QQQQ\bar{q}$ pentaquarks is given. In addition to the mass spectrum analysis, we also illustrate their two-body strong decay behavior by estimating some ratios of decay channels. By these effort, we suggest that future experiment should pay attention to this kind of pentaquark.

   hep-phPRD(2021)·20 citations
3. 03*

   Probing heavy charged fermions at $e^{+}{e}^{-}$ collider using the Optimal Observable Technique

   Subhaditya Bhattacharya (IIT Guwahati)🇮🇳 · Sahabub Jahedi (IIT Guwahati)🇮🇳 · Jose Wudka (UC Riverside)🇺🇸

   In this work we study the production of color-neutral and singly-charged heavy leptons at the proposed International Linear Collider. We use the optimal observable technique to determine the statistical accuracy to which the coupling of such fermions to the $Z$ gauge boson (vector, axial or chiral) can be measured. We also consider a UV-complete model that contains these particles as well as a dark matter candidate, and consider some observable effects involving both; the correspondence to chargino production in supersymmetric models with heavy sleptons is briefly discussed.

   hep-phJHEP(2022)·31 citations
4. 04*

   Neutrino-Nucleus scattering in the SuSA model

   J.E. Amaro🇪🇸 · M.B. Barbaro🇮🇹 · J.A. Caballero🇪🇸 · T.W. Donnelly🇺🇸 · R. Gonzalez-Jimenez🇪🇸 · G.D. Megias🇪🇸 · I. Ruiz Simo🇪🇸

   The Super-Scaling Approach (SuSA) model, based on the analogies between electron and neutrino interactions with nuclei, is reviewed and its application to the description of neutrino-nucleus scattering is presented. The contribution of both one- and two-body relativistic currents is considered. A selection of results is presented where theoretical predictions are compared with cross section measurements from the main ongoing neutrino oscillation experiments.

   hep-phhep-exnucl-thEur.Phys.J.ST(2021)·29 citations
5. 05*

   The THDMa revisited

   Tania Robens🇭🇷

   The THDMa is a new physics model that extends the scalar sector of the Standard Model by an additional doublet as well as a pseudoscalar singlet and allows for mixing between all possible scalar states. In the gauge-eigenbasis, the additional pseudoscalar serves as a portal to the dark sector, with a priori any dark matter spins states. The option where dark matter is fermionic is currently one of the standard benchmarks for the experimental collaborations, and several searches at the LHC constrain the corresponding parameter space. However, most current studies constrain regions in parameter space by setting all but 2 of the 12 free parameters to fixed values. In this work, we perform a generic scan on this model, allowing all parameters to float. We apply all current theoretical and experimental constraints, including bounds from current searches, recent results from B-physics, in particular B_s -> X_s gamma, as well as bounds from astroparticle physics. We identify regions in the parameter space which are still allowed after these have been applied and which might be interesting for an investigation at current and future collider machines.

   hep-phSymmetry(2021)·35 citations
6. 06*

   Maximally Symmetric Three Higgs Doublet Model

   Neda Darvishi🇬🇧 · M.R. Masouminia🇬🇧 · Apostolos Pilaftsis🇬🇧

   We consider the general Three-Higgs Doublet Model (3HDM) and identify all limits that lead to exact SM alignment. After discussing the underlying symmetries that can naturally enforce such an alignment, we focus on the most economic setting, called here the Maximally Symmetric Three-Higgs Doublet Model (MS-3HDM). The potential of the MS-3HDM obeys an $\mathrm{Sp}(6)$ symmetry, softly broken by bilinear masses and explicitly by hypercharge and Yukawa couplings through renormalisation-group effects, whilst the theory allows for quartic coupling unification up to the Planck scale. Besides the two ratios of vacuum expectation values, $\tan {\beta }_{1,2}$, the MS-3HDM is predominantly governed by only three input parameters: the masses of the two charged Higgs bosons, $M_{h_{1,2}^{\pm }}$, and their mixing angle $\sigma$. Most remarkably, with these input parameters, we obtain definite predictions for the entire scalar mass spectrum of the theory, as well as for the SM-like Higgs-boson couplings to the gauge bosons and fermions. The predicted deviations of these couplings from their SM values might be probed at future precision high-energy colliders. The new phenomenological aspects of the MS-3HDM with respect to the earlier studied MS-2HDM are discussed.

   hep-phPRD(2021)·40 citations
7. 07*

   Matching N3LO QCD calculations to parton showers

   Stefan Prestel🇸🇪

   The search for new interactions and particles in high-energy collider physics relies on precise background predictions. This has led to many advances in combining precise fixed-order cross-section calculations with detailed event generator simulations. In recent years, fixed-order QCD calculations of inclusive cross sections at N3LO precision have emerged, followed by an impressive progress at producing differential results. Once differential results become publicly available, it would be prudent to embed these into event generators to allow the community to leverage these advances. This note offers some concrete thoughts on ME+PS matching at third order in QCD. As a method for testing these thoughts, a toy calculation of $e^{+}{e}^{-}\to u\bar{u}$ at $\mathcal{O}({\alpha }_s^3)$ is constructed, and combined with an event generator through unitary matching. The toy implementation may serve also as blueprint for high-precision QCD predictions at future lepton colliders. As a byproduct of the N3LO matching formula, a new NNLO+PS formula for processes with "additional" jets is obtained.

   hep-phJHEP(2021)·24 citations
8. 08*

   Affleck-Dine Leptogenesis from Higgs Inflation

   Neil D. Barrie🇰🇷 · Chengcheng Han🇨🇳 · Hitoshi Murayama🇺🇸

   We find that the triplet Higgs of the Type II seesaw mechanism can simultaneously generate the neutrino masses and observed baryon asymmetry, while playing a role in inflation. We survey the allowed parameter space and determine that this is possible for triplet masses as low as a TeV, with a preference for a small vacuum expectation value for the triplet $v_{\Delta }<10$ keV. This requires that the triplet Higgs must decay dominantly into the leptonic channel. Additionally, this model will be probed at the future 100 TeV collider, upcoming lepton flavor violation experiments such as Mu3e, and neutrinoless double beta decay experiments. Thus, this simple framework provides a unified solution to the three major unknowns of modern physics - inflation, the neutrino masses, and the observed baryon asymmetry - while simultaneously providing unique phenomenological predictions that will be probed terrestrially at upcoming experiments.

   hep-phastro-ph.COhep-exhep-thPRL(2022)·53 citations
9. 09*

   Vanishing or non-vanishing rainbow? Reduction formulas of electric dipole moment

   Motoko Fujiwara🇯🇵 · Junji Hisano🇯🇵 · Takashi Toma🇯🇵

   In this paper, we derive a simplified formula of electric dipole moments (EDMs) of a fermion. In the Standard Model, it is well-known that non-trivial cancellations between some rainbow-type diagrams induced by $W$ boson exchanges occur in the calculation of the neutron EDM at the two-loop level due to the gauge symmetry. The fermion self-energy and the vertex correction are related through the Ward-Takahashi identity, and this relation causes the exact cancellation of the EDM. We derive EDM formulas for a more general setup by introducing the form factors for the fermion self-energy and the vertex correction so that the derived formulas can be applicable to a larger class of models. We conclude that the non-zero EDM contributions are induced from rainbow-type diagrams with the chirality flipping effects for internal fermions. We also discuss the other possible generalization of the EDM calculation which is applicable to the other classes of models.

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

    Inverse Seesaw Model with a Modular $S_4^{}$ Symmetry: Lepton Flavor Mixing and Warm Dark Matter

    Xinyi Zhang🇨🇳 · Shun Zhou🇨🇳

    In this paper, we present a systematic investigation on simple inverse seesaw models for neutrino masses and flavor mixing based on the modular $S_4^{}$ symmetry. Two right-handed neutrinos and three extra fermion singlets are introduced to account for light neutrino masses through the inverse seesaw mechanism, and to provide a keV-mass sterile neutrino as the candidate for warm dark matter in our Universe. Considering all possible modular forms with weights no larger than four, we obtain twelve models, among which we find one is in excellent agreement with the observed lepton mass spectra and flavor mixing. Moreover, we explore the allowed range of the sterile neutrino mass and mixing angles, by taking into account the direct search of $X$-ray line and the Lyman-$\alpha$ observations. The model predictions for neutrino mixing parameters and the dark matter abundance will be readily testable in future neutrino oscillation experiments and cosmological observations.

    hep-phastro-ph.COJCAP(2021)·39 citations
11. 11*

    Possibility of multi-step electroweak phase transition in the two Higgs doublet models

    Mayumi Aoki🇯🇵 · Takatoshi Komatsu🇯🇵 · Hiroto Shibuya🇯🇵

    We discuss whether a multi-step electroweak phase transition (EWPT) occurs in two Higgs doublet models (2HDMs). The EWPT is related to interesting phenomena such as baryogenesis and a gravitational wave from it. We examine parameter regions in CP-conserving 2HDMs and find certain areas where the multi-step EWPTs occur. The parameter search shows the multi-step EWPT prefers the scalar potential with the approximate $Z_2$ symmetry and a mass hierarchy between the neutral CP-odd and CP-even extra scalar bosons $m_A<m_H$. By contrast, the multi-step EWPT whose first step is strongly first order favors a mass hierarchy $m_A>m_H$. In addition, we compute the Higgs trilinear coupling in the parameter region where the multi-step EWPTs occur, which can be observed at future colliders. We also discuss a multi-peaked gravitational wave from a multi-step EWPT.

    hep-phPTEP(2022)·50 citations
12. 12*

    Classifying near-threshold enhancement using deep neural network

    Denny Lane B. Sombillo🇵🇭 · Yoichi Ikeda🇯🇵 · Toru Sato🇯🇵 · Atsushi Hosaka🇯🇵

    One of the main issues in hadron spectroscopy is to identify the origin of threshold or near-threshold enhancement. Prior to our study, there is no straightforward way of distinguishing even the lowest channel threshold-enhancement of the nucleon-nucleon system using only the cross-sections. The difficulty lies in the proximity of either a bound or virtual state pole to the threshold which creates an almost identical structure in the scattering region. Identifying the nature of the pole causing the enhancement falls under the general classification problem and supervised machine learning using a feed-forward neural network is known to excel in this task. In this study, we discuss the basic idea behind deep neural network and how it can be used to identify the nature of the pole causing the enhancement. The applicability of the trained network can be explored by using an exact separable potential model to generate a validation dataset. We find that within some acceptable range of the cut-off parameter, the neural network gives high accuracy of inference. The result also reveals the important role played by the background singularities in the training dataset. Finally, we apply the method to nucleon-nucleon scattering data and show that the network was able to give the correct nature of pole, i.e. virtual pole for ${}^1{S}_0$ partial cross-section and bound state pole for ${}^3{S}_0$.

    hep-phhep-exnucl-thFew Body Syst.(2021)·16 citations
13. 13*

    BSM global fits with GAMBIT: a Dark Matter EFT fit

    Tomás E. Gonzalo🇩🇪

    In this conference paper I present the first full global fit of a dark matter effective field theory with the global fitting framework GAMBIT. I show the results of exhaustive parameter space explorations of the effective dark matter model, including a general set of operators up to dimension 7, and using the most up-to-date constraints from direct and indirect detection of dark matter, relic abundance requirements and collider searches for dark matter candidates.

    hep-phastro-ph.CO1 citation
14. 14*

    Renormalon subtraction in OPE using Fourier transform: Formulation and application to various observables

    Yuuki Hayashi🇯🇵 · Yukinari Sumino🇯🇵 · Hiromasa Takaura🇯🇵

    Properly separating and subtracting renormalons in the framework of the operator product expansion (OPE) is a way to realize high precision computation of QCD effects in high energy physics. We propose a new method (FTRS method), which enables to subtract multiple renormalons simultaneously from a general observable. It utilizes a property of Fourier transform, and the leading Wilson coefficient is written in a one-parameter integral form whose integrand has suppressed (or vanishing) renormalons. The renormalon subtraction scheme coincides with the usual principal-value prescription at large orders. We perform test analyses and subtract the $\mathcal{O}({\Lambda }_{\mathrm{QCD}}^4)$ renormalon from the Adler function, the $\mathcal{O}({\Lambda }_{\mathrm{QCD}}^2)$ renormalon from the $B\to X_{u}l\bar{\nu }$ decay width, and the $\mathcal{O}({\Lambda }_{\mathrm{QCD}})$ and $\mathcal{O}({\Lambda }_{\mathrm{QCD}}^2)$ renormalons from the $B,D$ meson masses. The analyses show good consistency with theoretical expectations, such as improved convergence and scale dependence. In particular we obtain ${\bar{\Lambda }}_{\mathrm{FTRS}}=0.495\pm 0.053\text{GeV}$ and$({\mu }_{\pi }^2{)}_{\mathrm{FTRS}}=-0.12\pm 0.23{\text{GeV}}^2$ for the non-perturbative parameters of HQET. We explain the formulation and analyses in detail.

    hep-phJHEP(2022)·11 citations
15. 15*

    Light dark matter, rare $B$ decays with missing energy in $L_{\mu }-L_{\tau }$ model with a scalar leptoquark

    Shivaramakrishna Singirala🇮🇳 · Suchismita Sahoo🇮🇳 · Rukmani Mohanta🇮🇳

    We investigate the phenomenology of light GeV-scale fermionic dark matter in $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge extension of the Standard Model. Heavy neutral fermions alongside with a $S_1(\overline{3}$,$1$,$1/3$) scalar leptoquark and an inert scalar doublet are added to address the flavor anomalies and light neutrino mass respectively. The light gauge boson associated with $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge group mediates dark to visible sector and helps to obtain the correct relic density. Aided with a colored scalar, we constrain the new model parameters by using the branching ratios of various $b\to sll$ and $b\to s\gamma$ decay processes as well as the lepton flavour non-universality observables $R_{K^{(\ast )}}$ and then show the implication on the branching ratios of some rare semileptonic $B\to (K^{(\ast )},\varphi )+$ missing energy, processes.

    hep-phPRD(2022)·23 citations
16. 16*

    A simple alternative to the Breit-Wigner distribution

    Francesco Giacosa🇵🇱 · Anna Okopińska🇵🇱 · Vanamali Shastry🇵🇱

    First, we discuss the conditions under which the non-relativistic and relativistic types of the Breit-Wigner energy distributions are obtained. Then, upon insisting on the correct normalization of the energy distribution, we introduce a Flatté-like relativistic distribution -- denominated as Sill distribution -- that (i) contains left-threshold effects, (ii) is properly normalized for any decay width, (iii) can be obtained as an appropriate limit in which the decay width is a constant, (iv) is easily generalized to the multi-channel case (v) as well as to a convoluted form in case of a decay chain and -- last but not least -- (vi) is simple to deal with. We compare the Sill distribution to spectral functions derived within specific QFT models and show that it fairs well in concrete examples that involve a fit to experimental data for the $\rho$, $a_1(1260)$, and $K^{\ast }(982)$ mesons as well as the $\Delta (1232)$ baryon. We also present a study of the $f_2(1270)$ which has more than one possible decay channels. Finally, we discuss the limitations of the Sill distribution using the $a_0(980)$-$a_0(1450)$ and the $K_0^{\ast }(700)$-$K_0^{\ast }(1430)$ resonances as examples.

    hep-phquant-phEPJA(2021)·38 citations
17. 17*

    Partonic collinear structure by quantum computing

    Tianyin Li🇨🇳 · Xingyu Guo🇨🇳 · Wai Kin Lai🇨🇳 · Xiaohui Liu🇨🇳 · Enke Wang🇨🇳 · Hongxi Xing🇨🇳 · Dan-Bo Zhang🇨🇳 · Shi-Liang Zhu🇨🇳

    We present a systematic quantum algorithm, which integrates both the hadronic state preparation and the evaluation of real-time light-front correlators, to study parton distribution functions (PDFs). As a proof of concept, we demonstrate the first direct simulation of the PDFs in the 1+1 dimensional Nambu-Jona-Lasinio model. We show the results obtained by exact diagonalization and by quantum computation using classical hardware. The agreement between these two distinct methods and the qualitative consistency with QCD PDFs validate the proposed quantum algorithm. Our work suggests the encouraging prospects of calculating QCD PDFs on current and near-term quantum devices. The presented quantum algorithm is expected to have many applications in high energy particle and nuclear physics.

    hep-phhep-exnucl-thquant-phPRD(2022)·76 citations
18. 18*

    Twin Pati-Salam theory of flavour with a TeV scale vector leptoquark

    Stephen F. King🇬🇧

    We propose a twin Pati-Salam (PS) theory of flavour broken to the $G_{4321}$ gauge group at high energies, then to the Standard Model at low energies, yielding a TeV scale vector leptoquark $U_1^{\mu }(3,1,2/3)$ which has been suggested to address the lepton universality anomalies $R_{K^{(\ast )}}$ and $R_{D^{(\ast )}}$ in $B$ decays. Quark and lepton masses are mediated by vector-like fermions, with personal Higgs doublets for the second and third families, which may be replaced by a two Higgs doublet model (2HDM). The twin PS theory of flavour successfully accounts for all quark and lepton (including neutrino) masses and mixings, and predicts a dominant coupling of $U_1^{\mu }(3,1,2/3)$ to the third family left-handed doublets. However the predicted mass matrices, assuming natural values of the parameters, are not consistent with the single vector leptoquark solution to the $R_{D^{(\ast )}}$ anomaly, given its current value.

    hep-phJHEP(2021)·26 citations
19. 19*

    Gamma-Ray Flashes from Dark Photons in Neutron Star Mergers

    Melissa D. Diamond🇺🇸 · Gustavo Marques-Tavares🇺🇸

    In this letter we begin the study of visible dark sector signals coming from binary neutron star mergers. We focus on dark photons emitted in the 10 ms - 1 s after the merger, and show how they can lead to bright transient gamma-ray signals. The signal will be approximately isotropic, and for much of the interesting parameter space will be close to thermal, with an apparent temperature of about $100$ keV. These features can be used to distinguish the dark photon signal from the expected short gamma-ray bursts produced in neutron star mergers, which are beamed in a small angle and non-thermal. We calculate the expected signal strength and show that for dark photon masses in the $1-100$ MeV range it can easily lead to total luminosities larger than $10^{46}$ ergs for much of the unconstrained parameter space. This signal can be used to probe a large fraction of the unconstrained parameter space motivated by freeze-in dark matter scenarios with interactions mediated by a dark photon in that mass range. We also comment on future improvements when proposed telescopes and mid-band gravitational detectors become operational.

    hep-phastro-ph.COastro-ph.HEPRL(2022)·43 citations
20. 20*

    Machine learning based approach to fluid dynamics

    Kirill Taradiy🇩🇪 · Kai Zhou🇩🇪 · Jan Steinheimer🇩🇪 · Roman V. Poberezhnyuk🇺🇦 · Volodymyr Vovchenko🇺🇸 · Horst Stoecker🇩🇪

    We study the applicability of a Deep Neural Network (DNN) approach to simulate one-dimensional non-relativistic fluid dynamics. Numerical fluid dynamical calculations are used to generate training data-sets corresponding to a broad range of profiles to perform supervised learning with DNN. The performance of the DNN approach is analyzed, with a focus on its interpolation and extrapolation capabilities. Issues such as inference speed, the networks capacities to interpolate and extrapolate solutions with limited training samples from both initial geometries and evolution duration aspects are studied in detail. The optimal DNN performance is achieved when its objective is set to learn the mapping between hydro profiles after a fixed value time step, which can then be applied successively to reach moments in time much beyond the duration contained in the training. The DNN has an advantage over the conventional numerical methods by not being restricted by the Courant criterion, and it shows a speedup over the conventional numerical methods by at least two orders of magnitude.

    ↳ physics.comp-phhep-phphysics.data-anphysics.flu-dyn3 citations
21. 21*

    High-energy gamma-ray emission from SNR G57.2+0.8 hosting SGR J1935+2154

    Rita C. dos Anjos🇧🇷 · Jaziel G. Coelho🇧🇷 · Jonas P. Pereira🇵🇱 · Fernando Catalani🇨🇳

    In recent years some efforts have been made to identify active sources capable of accelerating particles up to $10^{15}$ eV, known as PeVatrons. Measurements of TeV ($10^{12}$ eV) gamma-rays from supernova remnants (SNRs) have shown that efficient particle acceleration can occur in SNR diffusive shocks. In this paper, we obtain the contribution to the high energy and very-high-energy gamma-ray (VHE, $E>100$ GeV) emission due to cosmic-ray acceleration from SNR G57.2+0.8 hosting the Soft Gamma Repeater (SGR) J1935+2154 with the use of the GALPROP code. To do so, we take into account the SNR + SGR association as a single source close to the Galactic center. We propose that the above setting can provide a more comprehensive scenario for the generation of GeV-TeV gamma-rays. We also discuss the contribution from the SNR G57.2+0.8 and SGR J1935+2154 region to the diffusive TeV energy gamma-ray emission from the Galactic center.

    ↳ astro-ph.HEastro-ph.SRhep-phhep-thJCAP(2021)·13 citations
22. 22*

    Do supernovae indicate an accelerating universe?

    Roya Mohayaee (IAP Paris)🇫🇷 · Mohamed Rameez (TIFR Mumbai)🇮🇳 · Subir Sarkar (Oxford)🇬🇧

    In the late 1990's, observations of 93 Type Ia supernovae were analysed in the framework of the FLRW cosmology assuming these to be `standard(isable) candles'. It was thus inferred that the Hubble expansion rate is accelerating as if driven by a positive Cosmological Constant $\Lambda$. This is still the only direct evidence for the `dark energy' that is the dominant component of the standard $\Lambda$CDM cosmological model. Other data such as BAO, CMB anisotropies, stellar ages, the rate of structure growth, etc are all `concordant' with this model but do not provide independent evidence for accelerated expansion. Analysis of a larger sample of 740 SNe Ia shows that these are not quite standard candles, and highlights the "corrections" applied to analyse the data in the FLRW framework. The latter holds in the reference frame in which the CMB is isotropic, whereas observations are made in our heliocentric frame in which the CMB has a large dipole anisotropy. This is assumed to be of kinematic origin i.e. due to our non-Hubble motion driven by local inhomogeneity in the matter distribution. The $\Lambda$CDM model predicts how this peculiar velocity should fall off as the averaging scale is raised and the universe becomes sensibly homogeneous. However observations of the local `bulk flow' are inconsistent with this expectation and convergence to the CMB frame is not seen. Moreover the kinematic interpretation implies a corresponding dipole in the sky distribution of high redshift quasars, which is rejected by observations at 4.9$\sigma$. The acceleration of the Hubble expansion rate is also anisotropic at 3.9$\sigma$ and aligned with the bulk flow. Thus dark energy may be an artefact of analysing data assuming that we are idealised observers in an FLRW universe, when in fact the real universe is inhomogeneous and anisotropic out to distances large enough to impact on cosmological analyses.

    ↳ astro-ph.COgr-qchep-phEur.Phys.J.ST(2021)·40 citations
23. 23*

    Lattice QCD Equation of State for Nonvanishing Chemical Potential by Resumming Taylor Expansion

    Sourav Mondal🇮🇳 · Swagato Mukherjee🇺🇸 · Prasad Hegde🇮🇳

    Taylor expansion in powers of baryon chemical potential (${\mu }_B$) is an oft-used method in lattice QCD to compute QCD thermodynamics for ${\mu }_B>0$. Based only upon the few known lowest order Taylor coefficients, it is difficult to discern the range of ${\mu }_B$ where such an expansion around ${\mu }_B=0$ can be trusted. We introduce a resummation scheme for the Taylor expansion of the QCD equation of state in ${\mu }_B$ that is based on the $n$-point correlation functions of the conserved current ($D_n$). The method resums the contributions of the first $N$ correlation function $D_1,\dots ,D_N$ to the Taylor expansion of the QCD partition function to all orders in ${\mu }_B$. We show that the resummed partition function is an approximation to the reweighted partition function at ${\mu }_B\ne 0$. We apply the proposed approach to high-statistics lattice QCD calculations using 2+1 flavors of Highly Improved Staggered Quarks with physical quark masses on $32^3\times 8$ lattices and for temperatures $T\approx 145$-176 MeV. We demonstrate that, as opposed to the Taylor expansion, the resummed version not only leads to improved convergence but also reflects the zeros of the resummed partition function and severity of the sign problem, leading to its eventual breakdown. We also provide a generalization of our scheme to include resummation of powers of temperature and quark masses in addition to ${\mu }_B$, and show that the alternative expansion scheme of [S. Borsányi et al., Phys. Rev. Lett. 126, 232001 (2021).] is a special case of this generalized resummation.

    ↳ hep-lathep-phnucl-exnucl-thPRL(2022)·45 citations
24. 24*

    Spins of primordial black holes formed in different cosmological scenarios

    Marcos M. Flores🇺🇸 · Alexander Kusenko🇺🇸

    Primordial black holes (PBHs) could account for all or part of dark matter, as well as for some LIGO events. We discuss the spins of primordial black holes produced in different cosmological scenarios, with the emphasis on recently discovered possibilities. PBHs produced as a horizon-size collapse of density perturbations are known to have very small spins. In contrast, PBHs resulting from assembly of matterlike objects (particles, Q-balls, oscillons, etc.) can have large or small spins depending on their formation history and the efficiency of radiative cooling. We show that scalar radiation can remove the angular momentum very efficiently, leading to slowly rotating PBHs in those scenarios for which the radiative cooling is important. Gravitational waves astronomy offers an opportunity to determine the spins of black holes, opening a new window on the early Universe if, indeed, some black holes have primordial origin.

    ↳ astro-ph.COhep-phPRD(2021)·45 citations
25. 25*

    GeV muon beams with picometer-class emittance from electron-photon collisions

    C. Curatolo🇮🇹 · L. Serafini🇮🇹

    One of the challenge of future muon colliders is the production of muon beams carrying high phase space densities. In particular the muon beam normalised transverse emittance is a relevant figure of merit to meet luminosity requests. A typical issue impacting the achieved transverse emittance in muon collider schemes so far considered is the phase space dilution caused by coulomb interaction of primary particles propagating into the target where muons are generated. In this study we present a new scheme for muon beam generation occurring in vacuum by interactions of electron and photon beams. Setting the center of mass energy at about twice the threshold (i.e. around $350$ MeV) the normalised emittance of the muon beam generated via muon pair production reaction ($e^{-}+\gamma \to e^{-}+{\mu }^{+}/{\mu }^{-}$) is largely independent on the emittance of the colliding electron beam and is set basically by the excess of transverse momentum in the muon pair creation. In absence of any other mechanism for emittance dilution, the resulting muon beam, with energy in the range of few tens of GeV, is characterised by an ultra-low normalised transverse rms emittance of a few nm rad, corresponding to a geometrical emittance below $10$ pm rad. This opens the way to a new muon collider paradigm based on muon sources conceived with primary colliding beams delivered by $100$ GeV-class energy recovery linacs interacting with hard-X ray free electron lasers. The challenge is to achieve the requested luminosity of the muon collider adopting a strategy of low muon fluxes/currents combined to ultra-low emittances, so to largely reduce also the levels of muon beam-induced background.

    ↳ physics.acc-phhep-phAppl.Sciences(2022)·7 citations
26. 26*

    Double parton distributions in the nucleon from lattice QCD

    Gunnar S. Bali🇩🇪 · Markus Diehl🇩🇪 · Benjamin Gläßle🇩🇪 · Andreas Schäfer🇩🇪 · Christian Zimmermann🇩🇪

    We evaluate nucleon four-point functions in the framework of lattice QCD in order to extract the first Mellin moment of double parton distributions (DPDs) in the unpolarized proton. In this first study, we employ an nf = 2 + 1 ensemble with pseudoscalar masses of mpi = 355 MeV and mK = 441 MeV. The results are converted to the scale mu = 2 GeV. Our calculation includes all Wick contractions, and for almost all of them a good statistical signal is obtained. We analyze the dependence of the DPD Mellin moments on the quark flavor and the quark polarization. Furthermore, the validity of frequently used factorization assumptions is investigated.

    ↳ hep-lathep-phJHEP(2021)·23 citations
27. 27*

    Recent results on top quark mass and properties and rare/anomalous top quarks interactions in CMS

    Sebastian Wuchterl (for the CMS Collaboration)🇩🇪

    The amount of data collected by the CMS experiment at the CERN LHC in the second data taking period provides the possibility to study absolute and differential cross sections of top quark interaction processes with high precision. Utilizing these results, fundamental standard model parameters such as the top quark mass are extracted. Moreover, given standard model measurements are interpreted in the context of Beyond the standard model theories. Recent results on top quark properties and rare or anomalous top quark interactions by CMS are presented in these proceedings. Furthermore, the implications of experimental results to effective field theory are discussed.

    ↳ hep-exhep-phSciPost Phys.Proc.(2022)·0 citations
28. 28*

    Twisted kink dynamics in multiflavor chiral Gross-Neveu model

    Michael Thies🇩🇪

    The Gross-Neveu model with ${\mathrm{U}}_L(N_f)\times {\mathrm{U}}_R(N_f)$ chiral symmetry is reconsidered in the large $N_c$ limit. The known analytical solution for the time dependent interaction of any number of twisted kinks and breathers is cast into a more revealing form. The ($x,t$)-dependent factors are isolated from constant coefficients and twist matrices. These latter generalize the twist phases of the single flavor model. The crucial tool is an identity for the inverse of a sum of two square matrices, derived from the known formula for the determinant of such a sum.

    ↳ hep-thcond-mat.str-elhep-phJ.Phys.A(2022)·4 citations
29. 29*

    Squeezing the Axion

    Jondalar L. J. Kuß🇩🇪 · David J. E. Marsh🇬🇧

    We apply the squeezed state formalism to scalar field dark matter (e.g. axion) perturbations generated during inflation. As for the inflationary perturbations, the scalar field state becomes highly squeezed as modes exit the horizon. For as long as $H>m_{\varphi }$ (with $H$ the Hubble rate and $m_{\varphi }$ the scalar mass) the scalar field field does not interact during reheating, and we follow its evolution exactly as modes re-enter the horizon. We find that the quantum state remains squeezed after horizon re-entry during the hot big bang. This demonstrates a fact well-known in the theory of inflation: cosmological observables for scalar dark matter are accurately modelled by a classical stochastic field with a fixed phase. Our calculation covers all modes smaller than the present-day cosmic de Broglie wavelength. Larger scale modes mix gravitationally with the environment when $H<m_{\varphi }$, and are thus expected to decohere.

    ↳ astro-ph.COhep-phquant-phOpen J.Astrophys.·13 citations
30. 30*

    Probing Dark Matter and Fundamental Physics with the Cherenkov Telescope Array

    F. Iocco · M. Meyer · M. Doro · W. Hofmann · J. Pérez-Romero · G. Zaharijas · A. Aguirre-Santaella · E. Amato · E.O. Anguner · L.A. Antonelli · Y. Ascasibar · C. Balázs and 62 other authors

    Astrophysical observations provide strong evidence that more than 80% of all matter in the Universe is in the form of dark matter (DM). Two leading candidates of particles beyond the Standard Model that could constitute all or a fraction of the DM content are the so-called Weakly Interacting Massive Particles (WIMPs) and Axion-Like Particles (ALPs). The upcoming Cherenkov Telescope Array, which will observe gamma rays between 20 GeV and 300 TeV with unprecedented sensitivity, will have unique capabilities to search for these DM candidates. A particularly promising target for WIMP searches is the Galactic Center. WIMPs with annihilation cross sections correctly producing the DM relic density will be detectable with CTA, assuming an Einasto-like density profile and WIMP masses between 200 GeV and 10 TeV. Regarding new physics beyond DM, CTA observations will also enable tests of fundamental symmetries of nature such as Lorentz invariance.

    ↳ astro-ph.HEhep-ph3 citations
31. 31*

    Crust-core transition of a neutron star: effect of the temperature under strong magnetic fields

    Márcio Ferreira🇵🇹 · Aziz Rabhi🇵🇹 · Constança Providência🇵🇹

    The effect of temperature on the crust-core transition of a magnetar is studied. The thermodynamical spinodals are used to calculate the transition region within a relativistic mean-field approach for the equation of state. Magnetic fields with intensities $5\times 10^{16}$ G and $5\times 10^{17}$ G are considered. It is shown that the effect on the extension of the crust-core transition is washed away for temperatures above $10^9$ K for magnetic field intensities $\lesssim 5\times 10^{16}$ G but may still persist if a magnetic field as high as $5\times 10^{17}$G is considered. For temperatures below that value, the effect of the magnetic field on crust-core transition is noticeable and grows as the temperature decreases and, in particular, it is interesting to identify the existence of disconnected non-homogeneous matter above the $B=0$ crust core transition density. Models with different symmetry energy slopes at saturation show quite different behaviors. In particular, a model with a large slope, as suggested by the recent results of PREX-2, predicts the existence of up to four disconnected regions of non-homogeneous matter above the zero magnetic field crust-core transition density.

    ↳ nucl-thastro-ph.HEhep-phEPJA(2021)·7 citations
32. 32*

    A study of potential non-relativistic QED pairs in the Keldysh-Schwinger formalism

    Tobias Binder🇯🇵

    Potential non-relativistic Quantum Electrodynamics and the Keldysh-Schwinger formalism is used to derive Kadanoff-Baym-like equations for two-body field correlators. These cover the out-off-equilibrium dynamics and spectrum of heavy particle-antiparticle pairs under ultra-soft transitions inside a plasma background, whose temperature is much smaller compared to the typical relative pair momentum. It is shown that the dynamical equation for the pair phase-space distribution function, containing recombination and dissociation via the electric dipole interactions, is consistent with the previous open quantum system treatment of bound states in the Coulomb limit of the two-body spectral function.

    ↳ hep-thcond-mat.quant-gascond-mat.str-elhep-ph1 citation
33. 33*

    Bayesian-Wilson coefficients in lattice QCD computations of valence PDFs and GPDs

    Nikhil Karthik🇺🇸 · Raza Sabbir Sufian🇺🇸

    We propose an analysis method for the leading-twist operator product expansion based lattice QCD determinations of the valence parton distribution function (PDF). In the first step, we determine the confidence-intervals of the leading-twist $\overline{\mathrm{MS}}$ Wilson coefficients, $C_n({\mu }^2{z}^2)$, of the equal-time bilocal quark bilinear, given the lattice QCD matrix element of Ioffe-time distribution for a particular hadron $H$ as well as the prior knowledge of the valence PDF, $f(x,\mu )$ of the hadron $H$ determined via global fit from the experimental data. In the next step, we apply the numerically estimated $C_n$ in the lattice QCD determinations of the valence PDFs of other hadrons, and for the zero-skewness generalized parton distribution (GPD) of the same hadron $H$ at non-zero momentum transfers. Our proposal still assumes the dominance of leading-twist terms, but it offers a pragmatic alternative to the usage of perturbative Wilson coefficients and their associated higher-loop uncertainties such as the effect of all-order logarithms at larger sub-Fermi quark-antiquark separations $z$.

    ↳ hep-lathep-phnucl-thPRD(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.