Fri·Jan 1, 2021Friday·January 1, 2021

1. 01*

   Single Production of Vectorlike Y Quarks at the HL-LHC

   V. Cetinkaya🇹🇷 · A. Ozansoy🇹🇷 · V. Ari🇹🇷 · O. M. Ozsimsek🇹🇷 · O. Cakir🇹🇷

   We study single production of exotic vectorlike $Y$ quark with electric charge $|Q_Y|=4/3$ and its subsequent decay at the High Luminosity LHC (HL-LHC). Most of the vector like quark (VLQ) decays have the electroweak $W$ bosons in the intermediate state. Besides their direct productions singly or pairs, the $W$-bosons are involved in decay chains as a result of the decay of a top quark which contributes to the background. This is particularly the case since vectorlike $Y$ quark, which is estimated to be produced with a high cross-section, can only decay via a $W$ boson and a down type quark ($d,s,b$). We calculate the cross sections of signal (for different couplings and mass values) and relevant Standard Model (SM) backgrounds. After a fast simulation of signal and background events, estimations of the sensitivity to the parameters (mass range 1000-2500 GeV for coupling value ${\kappa }_Y=0.5$, and mass range 500-2000 GeV for coupling values ${\kappa }_Y=0.3$ and ${\kappa }_Y=0.15$) have been presented at the HL-LHC with center of mass energy $\sqrt{s}=14$ TeV and integrated luminosity projections of 300 fb${}^{-1}$, 1000 fb${}^{-1}$ and 3000 fb${}^{-1}$.

   hep-phNPB(2021)·8 citations
2. 02*

   Self-interacting Dark Matter with Scalar Dilepton Mediator

   Chung Kao · Yue-Lin Sming Tsai · Gwo-Guang Wong

   The cold dark matter (CDM) candidate with weakly interacting massive particles can successfully explain the observed dark matter relic density in cosmic scale and the large-scale structure of the Universe. However, a number of observations at the satellite galaxy scale seem to be inconsistent with CDM simulation. This is known as the small-scale problem of CDM. In recent years, it has been demonstrated that self-interacting dark matter (SIDM) with a light mediator offers a reasonable explanation for the small-scale problem. We adopt a simple model with SIDM and focus on the effects of Sommerfeld enhancement. In this model, the dark matter candidate is a leptonic scalar particle with a light mediator. We have found several regions of the parameter space with proper masses and coupling strength generating a relic density that is consistent with the observed CDM relic density. Furthermore, this model satisfies the constraints of recent direct searches and indirect detection for dark matter as well as the effective number of neutrinos and the observed small-scale structure of the Universe. In addition, this model with the favored parameters can resolve the discrepancies between astrophysical observations and $N$-body simulations.

   hep-phastro-ph.HEPRD(2021)·3 citations
3. 03*

   Hairy Magnetic and Dyonic Black Holes in the Standard Model

   Yang Bai🇺🇸 · Mrunal Korwar🇺🇸

   Spherically symmetric magnetic and dyonic black holes with a magnetic charge $Q=2$ are studied in the Standard Model and general relativity. A magnetically charged black hole with mass below $9.3\times 10^{35}$ GeV has a "hairy" cloud of electroweak gauge and Higgs fields outside the event horizon with $1/m_W$ in size. An extremal magnetic black hole has a hair mass of 3.6 TeV, while an extremal dyonic black hole has an additional mass of $q^2\times 1.6$ GeV for a small electric charge $q\ll 2\pi /e^2$. A hairy dyonic black hole with an integer charge is not stable and can decay into a magnetic one plus charged fermions. On the other hand, a hairy magnetic black hole can evolve via Hawking radiation into a nearly extremal one that is cosmologically stable and an interesting object to be searched for.

   hep-phhep-thJHEP(2021)·29 citations
4. 04*

   Interplay between chiral dynamics and repulsive interactions

   Michał Marczenko · Krzysztof Redlich · Chihiro Sasaki

   We investigate fluctuations of the net-baryon number density in hot hadronic matter. We discuss the interplay between chiral dynamics and repulsive interactions and their influence on the properties of these fluctuations near the chiral crossover. The chiral dynamics is modeled by the parity doublet Lagrangian that incorporates the attractive and repulsive interactions mediated via the exchange of scalar and vector mesons, respectively. The mean-field approximation is employed to account for chiral criticality. We focus on the properties and systematics of the cumulants of the net-baryon number density up to the sixth order. It is shown that the higher-order cumulants exhibit a substantial suppression in the vicinity of the chiral phase transition due to the presence of repulsive interactions. We find, however, that the characteristic properties of cumulants near the chiral crossover observed in lattice QCD results are entirely linked to the critical chiral dynamics and, in general, cannot be reproduced in phenomenological models, which account only for effective repulsive interactions via excluded-volume corrections or van-der-Waals type interactions. Consequently, a description of the higher-order cumulants of the net-baryon density in the chiral crossover requires a self-consistent treatment of the chiral in-medium effects and repulsive interactions.

   hep-phPhys. Rev. D 103, 054035 (2021)
5. 05*

   Study of charmonium-like and fully-charm tetraquark spectroscopy

   Zheng Zhao🇹🇭 · Kai Xu🇹🇭 · Attaphon Kaewsnod🇹🇭 · Xuyang Liu🇹🇭 · Ayut Limphirat🇹🇭 · Yupeng Yan🇹🇭

   The masses of tetraquark states of all $qc\bar{q}\bar{c}$ and $cc\bar{c}\bar{c}$ quark configurations are evaluated in a constituent quark model, where the Cornell-like potential and one-gluon exchange spin-spin coupling are employed. All model parameters are predetermined by comparing the theoretical and experimental masses of light, charmed and bottom mesons. The theoretical predictions of the charmoniumlike tetraquarks are compared with the observed $XYZ$ states, and one tentative assignment is suggested. The work suggests that the $X(6900)$ observed by LHCb is likely to be the first radial excited fully-charm tetraquark state with $J^{PC}=1^{+-}$ in the ${\bar{3}}_c\otimes 3_c$ configuration, and the ground and second radial excited states of fully-charm tetraquark are around $6494$ and $7253$ MeV respectively.

   hep-phPRD(2021)·72 citations
6. 06*

   EFT for Soft Drop Double Differential Cross Section

   Aditya Pathak🇬🇧 · Iain W. Stewart🇺🇸 · Varun Vaidya🇺🇸 · Lorenzo Zoppi🇳🇱

   We develop a factorization framework to compute the double differential cross section in soft drop groomed jet mass and groomed jet radius. We describe the effective theories in the large, intermediate, and small groomed jet radius regions defined by the interplay of the jet mass and the groomed jet radius measurement. As an application we present the NLL${}^{\prime }$ results for the perturbative moments that are related to the coefficients $C_1$ and $C_2$ that specify the leading hadronization corrections up to three universal parameters. We compare our results with Monte Carlo simulations and a calculation using the coherent branching method.

   hep-phJHEP(2021)·16 citations
7. 07*

   The Genuine Type-V Seesaw Model: Phenomenological Introduction

   Saiyad Ashanujjaman🇮🇳 · Kirtiman Ghosh🇮🇳

   We study a model which generates Majorana neutrino masses at tree-level via low-energy effective operator with mass-dimension-9. Introduction of such a higher dimensional operator brings down the lepton number violating mass scale to TeV making such model potentially testable at present or near future colliders. This model possesses several new $SU(2{)}_L$ fermionic multiplets, in particular, three generations of triplets, quadruplets and quintuplets, and thus a rich phenomenology at the LHC. As the lepton flavour violation arises very naturally in such setup, we put constraints on the Yukawa couplings and heavy fermion masses from the current experimental bounds on lepton flavour violating processes. We also obtain 95% CL lower bounds on the masses of the triplets, quadruplets and quintuplets using a recent CMS search for multilepton final states with 137 inverse femtobarn integrated luminosity data at 13 TeV center of mass energy. The possibility that the heavy fermions could be long-lived leaving disappearing charge track signatures or displaced vertex at the future colliders like LHeC, FCC-he, MATHUSLA, etc. is also discussed.

   hep-phJHEP(2021)·6 citations
8. 08*

   Search for Low-Mass Leptoquarks using the $llqq$ final states in Pb-Pb Ultra-Peripheral Collisions

   Li-Gang Xia🇨🇳

   After a review over past experiments and theoretical requirements from low-energy flavour physics, we argue that the possibility of low-mass leptoquarks (LQ) cannot be fully excluded due to the assumptions made in the measurements. Therefore we propose to search for the pair production of low-mass leptoquarks in Pb-Pb ultra-peripheral collisions with the least model dependence (assuming a small coupling constant $\lesssim 0.1$). There are a couple of advantages: 1) high photon flux provides high production rate for low mass LQs; 2) the background contamination is much lower than that in $p$-$p$ collisions. The analysis strategy permits a leptoquark to decay to all possible lepton-plus-quark modes. Taking the scalar LQ, $S_3$, with an electric charge $|q|=\frac{4}{3}e$, as example, the mass point of 100 GeV can be excluded at the 95~\% confidence level using a dataset of 4~pb${}^{-1}$ Pb-Pb ultra-peripheral collisions at $\sqrt{s}=5.02$ TeV and the performance of the ATLAS detector in Run~2. The proposed method also applies to searching for high-mass LQs in $p$-$p$ collisions as long as the LQ pair production mechanism dominates.

   hep-phhep-exJHEP(2021)·1 citation
9. 09*

   Higgs-mass predictions in the MSSM and beyond

   P. Slavich🇫🇷 · S. Heinemeyer🇪🇸 · E. Bagnaschi🇨🇭 · H. Bahl🇩🇪 · M. Goodsell🇫🇷 · H.E. Haber🇺🇸 · T. Hahn🇩🇪 · R. Harlander🇩🇪 · W. Hollik🇩🇪 · G. Lee🇺🇸 · M. Mühlleitner🇩🇪 · S. Paßehr🇩🇪 and 27 other authors

   Predictions for the Higgs masses are a distinctive feature of supersymmetric extensions of the Standard Model, where they play a crucial role in constraining the parameter space. The discovery of a Higgs boson and the remarkably precise measurement of its mass at the LHC have spurred new efforts aimed at improving the accuracy of the theoretical predictions for the Higgs masses in supersymmetric models. The "Precision SUSY Higgs Mass Calculation Initiative" (KUTS) was launched in 2014 to provide a forum for discussions between the different groups involved in these efforts. This report aims to present a comprehensive overview of the current status of Higgs-mass calculations in supersymmetric models, to document the many advances that were achieved in recent years and were discussed during the KUTS meetings, and to outline the prospects for future improvements in these calculations.

   hep-phEPJC(2021)·134 citations
10. 10*

    Hydrodynamic attractor and novel fixed points in superfluid Bjorken flow

    Toshali Mitra🇮🇳 · Ayan Mukhopadhyay🇮🇳 · Alexander Soloviev🇺🇸

    Extending the quantum effective approach of Son and Nicolis and incorporating dissipation, we develop a MIS formalism for describing a superfluid out of equilibrium by including the Goldstone boson and the condensate together with the hydrodynamic modes as the effective degrees of freedom. We find that the evolution of the superfluid undergoing Bjorken flow is governed by the conventional hydrodynamic attractor with unbroken symmetry and an even number of novel non-dissipative fixed points with broken symmetry. If the initial temperature is super-critical, then the condensate becomes exponentially small very rapidly and the system is trapped by the hydrodynamic attractor for a long intermediate time before it reheats rapidly and switches to one of the symmetry-breaking fixed points eventually. Finally, we show that the fixed points are unstable against inhomogeneous perturbations that should lead to spinodal decomposition. We conclude that these features should be generic beyond the MIS formalism.

    hep-phcond-mat.quant-gashep-thPRD(2021)·12 citations
11. 11*

    Rigorous treatment of the ${\mathcal{S}}^1/{\mathbb{Z}}_2$ orbifold model with brane-Higgs couplings

    Ruifeng Leng🇫🇷 · Grégory Moreau🇫🇷 · Florian Nortier🇫🇷

    We build rigorously the attractive five-dimensional model where bulk fermions propagate along the ${\mathcal{S}}^1/{\mathbb{Z}}_2$ orbifold and interact with a Higgs boson localised at a fixed point of the extra dimension. The analytical calculation of the fermion mass spectrum and effective Yukawa couplings is shown to require the introduction of either Essential Boundary Conditions (EBC) imposed by the model definition or certain Bilinear Brane Terms (BBT) in the action, instead of the usual brane-Higgs regularisations. The obtained fermion profiles along the extra dimension turn out to undergo some discontinuities, in particular at the Higgs brane, which can be mathematically consistent if the action is well written with improper integrals. We also show that the ${\mathbb{Z}}_2$ parity transformations in the bulk do not affect the fermion chiralities, masses and couplings, in contrast with the EBC and BBT, but when extended to the fixed points, they can generate the chiral nature of the theory and even select the Standard Model chirality set-up while fixing as well the fermion masses and couplings. Thanks to the strict analysis developed, the duality with the interval model is scrutinised.

    hep-phhep-thPRD(2021)·3 citations
12. 12*

    New method for renormalon subtraction using Fourier transform

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

    To improve accuracy in calculating QCD effects, we propose a method for renormalon subtraction in the context of the operator-product expansion. The method enables subtracting renormalons of various powers in ${\Lambda }_{\mathrm{QCD}}$ efficiently and simultaneously from single-scale observables. We apply it to different observables and examine consistency with theoretical expectations.

    hep-phPLB(2021)·7 citations
13. 13*

    Radiative corrections for the decay ${\Sigma }^0\to \Lambda e^{+}{e}^{-}$

    Tomáš Husek (Charles U.)🇨🇿

    Electromagnetic form factors serve to explore the intrinsic structure of nucleons and their strangeness partners. For the decay ${\Sigma }^0\to \Lambda e^{+}{e}^{-}$, due to limited phase space, the effects caused by the Sigma-to-Lambda transition form factors compete with the QED radiative corrections. These corrections are addressed in the present work, evaluated beyond the soft-photon approximation, i.e., over the whole range of the Dalitz plot and with no restrictions on the energy of the radiative photon.

    hep-phhep-exPoS(2021)·0 citations
14. 14*

    Lepton-flavour violation in hadronic tau decays and $\ell$-$\tau$ conversion in nuclei

    Tomáš Husek (Charles U.)🇨🇿 · Kevin Monsálvez-Pozo🇪🇸 · Jorge Portolés (IFIC, Valencia)🇪🇸

    Within the Standard Model Effective Field Theory framework, with operators up to dimension 6, we perform a model-independent analysis of the lepton-flavour-violating processes involving tau leptons. Namely, we study hadronic tau decays and $\ell$-$\tau$ conversion in nuclei ($\ell =e,\mu$). Based on available experimental limits, we establish constraints on the Wilson coefficients of the operators contributing to these processes. The related information from Belle II and foreseen future experiments can be easily incorporated into the resulting framework.

    hep-phhep-exPoS(2021)·2 citations
15. 15*

    Color-octet scalars in Dirac gaugino models with broken $R$ symmetry

    Linda M. Carpenter🇺🇸 · Taylor Murphy🇺🇸

    In this work we study the collider phenomenology of color-octet scalars (sgluons) in supersymmetric models with Dirac gaugino masses that feature an explicitly broken $R$ symmetry ($R$-broken models). We construct such models by augmenting minimal $R$-symmetric models with a fairly general set of supersymmetric and softly supersymmetry-breaking operators that explicitly break $R$ symmetry. We then compute the rates of all significant two-body decays and highlight new features that appear as a result of $R$ symmetry breaking, including enhancements to extant decay rates, novel tree- and loop-level decays, and improved cross sections of single sgluon production. We demonstrate in some detail how the familiar results from minimal $R$-symmetric models can be obtained by restoring $R$ symmetry. In parallel to this discussion, we explore constraints on these models from the Large Hadron Collider. We find that, in general, $R$ symmetry breaking quantitatively affects existing limits on color-octet scalars, perhaps closing loopholes for light CP-odd (pseudoscalar) sgluons while opening one for a light CP-even (scalar) particle. Qualitatively, however, we find that -- much as for minimal $R$-symmetric models, despite stark differences in phenomenology -- scenarios with broken $R$ symmetry and two sgluons below the TeV scale can be accommodated by existing searches.

    hep-phJHEP(2021)·13 citations
16. 16*

    Exploring charm decays with missing energy in leptoquark models

    Gaber Faisel🇹🇷 · Jhih-Ying Su🇹🇼 · Jusak Tandean🇹🇼

    We investigate the possibility that scalar leptoquarks generate consequential effects on the flavor-changing neutral-current decays of charmed hadrons into final states with missing energy ($/E$) carried away by either standard model or sterile neutrinos. We focus on scenarios involving the $R_2$, ${\tilde{R}}_2$, and ${\bar{S}}_1$ leptoquarks and take into account various pertinent constraints, learning that meson-mixing ones and those inferred from collider searches can be of significance. We find in particular that the branching fractions of charmed meson decays $D\to M/E$, $M=\pi ,\rho$, and $D_s\to K^{(\ast )}/E$ and singly charmed baryon decays ${\Lambda }_c^{+}\to p/E$ and ${\Xi }_c\to \Sigma /E$ are presently allowed to attain the $10^{-7}$-$10^{-6}$ levels if induced by $R_2$ and that the impact of ${\tilde{R}}_2$ is comparatively much less. In contrast, the contributions of ${\bar{S}}_1$, which couples to right-handed up-type quarks and the sterile neutrinos, could lead to branching fractions as high as order $10^{-3}$. This suggests that these charmed hadron decays might be within reach of the BESIII and Belle II experiments or future super charm-tau factories and could serve as potentially promising probes of leptoquark interactions with sterile neutrinos.

    hep-phhep-exJHEP(2021)·18 citations
17. 17*

    The ${ϵ}^{\prime }/ϵ$-Story: 1976-2021

    Andrzej J. Buras🇩🇪

    The ratio ${ϵ}^{\prime }/ϵ$ measures the size of the direct CP violation in $K_L\to \pi \pi$ decays $({ϵ}^{\prime })$ relative to the indirect one described by $ϵ$ and is very sensitive to new sources of CP violation. As such it played a prominent role in particle physics already for 45 years. Due to the smallness of ${ϵ}^{\prime }/ϵ$ its measurement required heroic efforts in the 1980s and the 1990s on both sides of the Atlantic with final results presented by NA48 and KTeV collaborations 20 years ago. Unfortunately, even 45 years after the first calculation of ${ϵ}^{\prime }/ϵ$ we do not know to which degree the Standard Model agrees with this data and how large is the room left for new physics contributions to this ratio. This is due to significant non-perturbative (hadronic) uncertainties accompanied by partial cancellation between the QCD penguin contributions and electroweak penguin contributions. While the significant control over the short distance perturbative effects has been achieved already in the early 1990s, with several improvements since then, different views on the non-perturbative contributions to ${ϵ}^{\prime }/ϵ$ have been expressed by different authors over last thirty years. In fact even today the uncertainty in the room left for NP contributions to ${ϵ}^{\prime }/ϵ$ is very significant. My own work on ${ϵ}^{\prime }/ϵ$ started in 1983 and involved both perturbative and non-perturbative calculations. This writing is a non-technical recollection of the steps which led to the present status of ${ϵ}^{\prime }/ϵ$ including several historical remarks not known to everybody. The present status of the $\Delta I=1/2$ rule is also summarized. This story is dedicated to Jean-Marc Gerard on the occasion of the 35th anniversary of our collaboration and his 64th birthday.

    hep-phhep-exhep-latActa Phys.Polon.B(2021)·21 citations
18. 18*

    $\text{RGE++}:$ A $\text{C++}$ library to solve renormalisation group equations in quantum field theory

    Thomas Deppisch🇩🇪 · Florian Herren🇩🇪

    In recent years three-, four- and five-loop beta functions have been computed for various phenomenologically interesting models. However, most of these results have not been implemented in easy to use software packages. $\text{RGE++}$ bridges this gap by providing a flexible, template-based, $\text{C++}$ library to solve renormalisation group equations. Furthermore, we implement the available beta functions for the Standard Model, the minimal supersymmetric extension of the Standard Model and two-Higgs-doublet models, as well as right-handed neutrino extensions of the former two.

    hep-phComput.Phys.Commun.(2022)·6 citations
19. 19*

    True Dynamical and Gauge Structures of the QCD Ground State and the Singular Gluon Fileds

    Vakhtang Gogokhia🇭🇺 · Gergely Gábor Barnaföldi🇭🇺

    We convincingly argue that the true dynamical and gauge structure of the QCD ground state is much more complicated than its Lagrangian exact gauge symmetry supposes to be. The dynamical source of these complications has been identified with the tadpole/seagull term, which renormalized version called, the mass gap. Its true dynamical role is hidden in the QCD ground state, but it is explicitly present in the full gluon self-energy. To disclose it the splintering between the transverse conditions for the full gluon self-energy and its subtracted counterpart has been derived. The equation of motion for the full gluon propagator on account of the mass gap was given, which allows to fix the dynamical and gauge structures by a newly-introduced generalized gauge. A novel non-perturbative analytical method, the mass gap approach was developed for QCD and its groud state as well. We have discovered a general, non-perturbative singular solution for the full gluon propagator valid in the whole gluon momentum range, while dominating at large distances over all the other possible solutions. It accommodates all the severe infrared singularities, which may appear in the QCD ground state due to the self-interaction of massless gluon modes. A corresponding non-pertubative multiplicative infrared renormalization program has been formulated. The resulting full gluon propagator prevents gluons to appear at large distances as physical states (confinement of color gluons). Our approach also explains the scale violation in the asymptotic freedom regime, and why the rising potential between heavy quarks is only linear one.

    ↳ hep-thhep-phnucl-th1 citation
20. 20*

    Self-consistent conversion of a one-component bulk viscous fluid to particles

    Denes Molnar ((1) Purdue University, (2) Wigner Research Center for Physics, Budapest)

    Comparison of heavy-ion experiments to fluid dynamics simulations requires the conversion of the fluid to particles. Extending the approach in Molnar & Wolff, PRC 95, 024903 (2017), this work presents self-consistent bulk viscous corrections from kinetic theory for a one-component system with isotropic $2\to 2$ interactions. The phase space corrections are contrasted to the Grad ansatz and also to corrections obtained from the relaxation time approximation. In addition, the bulk viscosity of the system is calculated and compared with the Grad result, as well as the $\zeta \propto (1-3c_s^2{)}^2\eta$ relation between shear and bulk viscosity near the conformal limit. The possible influence of various bulk correction choices on differential elliptic flow $v_2(p_T)$ in heavy-ion collisions is also estimated.

    ↳ nucl-thhep-ph0 citations
21. 21*

    Magnetic field and gravitational waves from the first-order Phase Transition

    Yuefeng Di🇨🇳 · Jialong Wang🇨🇳 · Ruiyu Zhou🇨🇳 · Ligong Bian🇨🇳 · Rong-Gen Cai🇨🇳 · Jing Liu🇨🇳

    We perform the three dimensional lattice simulation of the magnetic field and gravitational wave productions from bubble collisions during the first-order electroweak phase transition. Except that of the gravitational wave, the power-law spectrum of the magnetic field strength is numerically calculated for the first time, which is of a broken power-law spectrum: $B_{\xi }\propto f^{0.91}$ for low frequency region of $f<f_{\star }$ and $B_{\xi }\propto f^{-1.65}$ for high frequency region of $f>f_{\star }$ in the thin-wall limit, with the peak frequency being $f_{\star }\sim 5$ Hz at the phase transition temperature 100 GeV. When the hydrodynamics is taken into account, the generated magnetic field strength can reach $B_{\xi }\sim 10^{-7}$G at a correlation length $\xi \sim 10^{-7}$pc, which may seed the large scale magnetic fields. Our study shows that the measurements of cosmic magnetic field strength and gravitational waves are complementary to probe new physics admitting electroweak phase transition.

    ↳ astro-ph.COhep-lathep-phPRL(2021)·67 citations
22. 22*

    Massive One-loop Conformal Feynman Integrals and Quadratic Transformations of Multiple Hypergeometric Series

    B. Ananthanarayan🇮🇳 · Sumit Banik🇮🇳 · Samuel Friot🇫🇷 · Shayan Ghosh🇩🇪

    The computational technique of $N$-fold Mellin-Barnes (MB) integrals, presented in a companion paper by the same authors, is used to derive sets of series representations of the massive one-loop conformal 3-point Feynman integral in various configurations. This shows the great simplicity and efficiency of the method in nonresonant cases (generic propagator powers) as well as some of its subtleties in the resonant ones (for unit propagator powers). We confirm certain results in the physics and mathematics literature and provide many new results, some of them dealing with the more general massive one-loop conformal $n$-point case. In particular, we prove two recent conjectures that give the massive one-loop conformal $n$-point integral (for generic propagator powers) in terms of multiple hypergeometric series. We show how these conjectures, that were deduced from a Yangian bootstrap analysis, are related by a tower of new quadratic transformations in Hypergeometric Functions Theory. Finally, we also use our MB method to identify spurious contributions that can arise in the Yangian approach.

    ↳ hep-thhep-phmath-phmath.MPPRD(2021)·18 citations
23. 23*

    Holographic approach of the spinodal instability to criticality

    Maximilian Attems🇨🇭

    A smoking gun signature for a first-order phase transition with negative speed of sound squared $c_s^2$ is the occurrence of a spinodal instability. In the gauge/gravity duality it corresponds to a Gregory-Laflamme type instability, which can be numerically simulated as the evolution of unstable planar black branes. Making use of holography its dynamics is studied far from and near a critical point with the following results. Near a critical point the interface between cold and hot stable phases, given by its width and surface tension, is found to feature a wider phase separation and a smaller surface tension. Far away from a critical point the formation time of the spinodal instability is reduced. Across softer and harder phase transitions, it is demonstrated that mergers of equilibrated peaks and unstable plateaux lead to the preferred final single phase separated solution. Finally, a new atypical setup with dissipation of a peak into a plateau is discovered. In order to distinguish the inhomogeneous states I propose a new criterium based on the maximum of the transverse pressure at the interface which encodes phase-mixed peaks versus fully phase separated plateaux.

    ↳ hep-thgr-qchep-phJHEP(2021)·18 citations
24. 24*

    Studying the onset of deconfinement with multi-messenger astronomy of neutron stars

    David Blaschke🇵🇱 · Mateusz Cierniak🇵🇱

    With the first multi-messenger observation of a binary neutron star merger (GW170817) new constraints became available for masses and radii of neutron stars. We introduce a class of hybrid EoS that fulfils all these constraints and predicts a region in the mass-radius diagram that could be populated only by hybrid neutron stars with quark matter cores. A confirmation of this conjecture would be provided when the NICER radius measurement for the high-mass pulsar PSR J0740+6620 yields a radius less than 11 km. Would this radius measurement yield a result in excess of 12 km, this would allow for both, a purely hadronic and a hybrid nature of this star. In the latter case the maximum mass could reach $2.6M_{\odot }$ so that the lighter object in the asymmetric binary merger GW190814 could have been a hybrid star. We demonstrate that this high mass can be compatible with an early onset of deconfinement at star masses below $1M_{\odot }$ and the occurrence of low-mass twin stars. In such a case the remnant of GW170817 could be a long-lived hypermassive pulsar.

    ↳ astro-ph.HEhep-phnucl-thAstron.Nachr.(2021)·34 citations
25. 25*

    Constraints on quasinormal modes and bounds for critical points from pole-skipping

    Navid Abbasi🇨🇳 · Matthias Kaminski🇺🇸

    We consider a holographic thermal state and perturb it by a scalar operator whose associated real-time Green's function has only gapped poles. These gapped poles correspond to the non-hydrodynamic quasinormal modes of a massive scalar perturbation around a Schwarzschild black brane. Relations between pole-skipping points, critical points and quasinormal modes in general emerge when the mass of the scalar and hence the dual operator dimension is varied. First, this novel analysis reveals a relation between the location of a mode in the infinite tower of quasinormal modes and the number of pole-skipping points constraining its dispersion relation at imaginary momenta. Second, for the first time, we consider the radii of convergence of the derivative expansions about the gapped quasinormal modes. These convergence radii turn out to be bounded from above by the set of all pole-skipping points. Furthermore, a transition between two distinct classes of critical points occurs at a particular value for the conformal dimension, implying close relations between critical points and pole-skipping points in one of those two classes. We show numerically that all of our results are also true for gapped modes of vector and tensor operators.

    ↳ hep-thcond-mat.mes-hallcond-mat.str-elhep-ph+1JHEP(2021)·44 citations
26. 26*

    Backreaction of Schwinger pair creation in massive QED${}_2$

    Gregory Gold🇩🇰 · David A. McGady🇸🇪 · Subodh P. Patil🇩🇰 · Valeri Vardanyan🇯🇵

    Particle-antiparticle pairs can be produced by background electric fields via the Schwinger mechanism provided they are unconfined. If, as in QED in (3+1)-$d$ these particles are massive, the particle production rate is exponentially suppressed below a threshold field strength. Above this threshold, the energy for pair creation must come from the electric field itself which ought to eventually relax to the threshold strength. Calculating this relaxation in a self-consistent manner, however, is difficult. Chu and Vachaspati addressed this problem in the context of capacitor discharge in massless QED${}_2$ [1] by utilizing bosonization in two-dimensions. When the bare fermions are massless, the dual bosonized theory is free and capacitor discharge can be analyzed exactly [1], however, special care is required in its interpretation given that the theory exhibits confinement. In this paper we reinterpret the findings of [1], where the capacitors Schwinger-discharge via electrically neutral dipolar meson-production, and generalize this to the case where the fermions have bare masses. Crucially, we note that when the initial charge of the capacitor is large compared to the charge of the fermions, $Q\gg e$, the classical equation of motion for the bosonized model accurately characterizes the dynamics of discharge. For massless QED${}_2$, we find that the discharge is suppressed below a critical plate separation that is commensurate with the length scale associated with the meson dipole moment. For massive QED${}_2$, we find in addition, a mass threshold familiar from (3+1)-$d$, and show the electric field relaxes to a final steady state with a magnitude proportional to the initial charge. We discuss the wider implications of our findings and identify challenges in extending this treatment to higher dimensions.

    ↳ hep-thhep-phJHEP(2021)·12 citations
27. 27*

    The EFT-Hedron

    Nima Arkani-Hamed🇺🇸 · Tzu-Chen Huang🇺🇸 · Yu-tin Huang🇹🇼

    We re-examine the constraints imposed by causality and unitarity on the low-energy effective field theory expansion of four-particle scattering amplitudes, exposing a hidden "totally positive" structure strikingly similar to the positive geometries associated with grassmannians and amplituhedra. This forces the infinite tower of higher-dimension operators to lie inside a new geometry we call the "EFThedron". We initiate a systematic investigation of the boundary structure of the EFThedron, giving infinitely many linear and non-linear inequalities that must be satisfied by the EFT expansion in any theory. We illustrate the EFThedron geometry and constraints in a wide variety of examples, including new consistency conditions on the scattering amplitudes of photons and gravitons in the real world.

    ↳ hep-thhep-phJHEP(2021)·335 citations
28. 28*

    Ultra Unification

    Juven Wang🇺🇸

    Strong, electromagnetic, and weak forces were unified in the Standard Model (SM) with spontaneous gauge symmetry breaking. These forces were further conjectured to be unified in a simple Lie group gauge interaction in the Grand Unification (GUT). In this work, we propose a theory beyond the SM and GUT by adding new gapped Topological Phase Sectors consistent with the nonperturbative global anomaly cancellation and cobordism constraints (especially from the baryon minus lepton number $\mathbf{B}-\mathbf{L}$, the electroweak hypercharge $Y$, and the mixed gauge-gravitational anomaly). Gapped Topological Phase Sectors are constructed via symmetry extension, whose low energy contains unitary Lorentz invariant topological quantum field theories (TQFTs): either 3+1d non-invertible TQFT, or 4+1d invertible or non-invertible TQFT (short-range or long-range entangled gapped phase). Alternatively, there could also be right-handed "sterile" neutrinos, gapless unparticle physics, more general interacting conformal field theories, or gravity with topological cobordism constraints, or their combinations to altogether cancel the mixed gauge-gravitational anomaly. We propose that a new high-energy physics frontier beyond the conventional 0d particle physics relies on the new Topological Force and Topological Matter including gapped extended objects (gapped 1d line and 2d surface operators or defects, etc., whose open ends carry deconfined fractionalized particle or anyonic string excitations) or gapless conformal matter. Physical characterizations of these gapped extended objects require the mathematical theories of cohomology, cobordism, or category. Although weaker than the weak force, Topological Force is infinite-range or long-range which does not decay in the distance, and mediates between the linked worldvolume trajectories via fractional or categorical statistical interactions.

    ↳ hep-thcond-mat.str-elhep-phPRD(2021)·35 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.