Nuclear Theory·nucl-th

Friday·October 25, 2024

8 papers—2 primary·6 cross-listed

03
$2 + 1$ dimensional Floquet systems and lattice fermions: Exact bulk spectral equivalence
Thomas Iadecola🇺🇸 · Srimoyee Sen🇺🇸 · Lars Sivertsen🇺🇸
A connection has recently been proposed between periodically driven systems known as Floquet insulators in continuous time and static fermion theories in discrete time. This connection has been established in a $(1 + 1)$ -dimensional free theory, where an explicit mapping between the spectra of a Floquet insulator and a discrete-time Dirac fermion theory has been formulated. Here we investigate the potential of static discrete-time theories to capture Floquet physics in higher dimensions, where so-called anomalous Floquet topological insulators can emerge that feature chiral edge states despite having bulk bands with zero Chern number. Starting from a particular model of an anomalous Floquet system, we provide an example of a static discrete-time theory whose bulk spectrum is an exact analytic match for the Floquet spectrum. The spectra with open boundary conditions in a particular strip geometry also match up to finite-size corrections. However, the models differ in several important respects. The discrete-time theory is spatially anisotropic, so that the spectra do not agree for all lattice terminations, e.g. other strip geometries or on half spaces. This difference can be attributed to the fact that the static discrete-time model is quasi-one-dimensional in nature and therefore has a different bulk-boundary correspondence than the Floquet model.
↳ quant-phhep-lathep-thnucl-thSciPost Phys.Core(2025)·1 citation
04
XTE J1814-338: A potential hybrid star candidate
P. Laskos-Patkos · Ch.C. Moustakidis
A recent analysis on the properties of the XTE J1814-338 pulsar yielded a small radius value around ~ 7 km. Notably, this estimation is significantly lower compared to the currently inferred values for the radius of neutron stars (as they are derived from both theoretical calculations and corresponding observations). In this paper, we focus on the construction of hybrid equations of state (EOSs) for the possible reconciliation of the exotic XTE J1814-338 properties. Our analysis indicates that an equation of state involving a sufficiently strong phase transition could potentially lead to the explanation of the size and mass of such a compact object. By examining the sign of the $d M / d P_{c}$ slope, we found that stellar configurations compatible to XTE J1814-338 are only stable for a "stiff" low density phase. For a "soft" hadronic EOS selection the stability of the resulting configurations may not be satisfied in terms of the turning point criterion. However, a complementary analysis, for the radial oscillations of the aforementioned configurations, indicated their stability when a slow phase conversion is considered.
↳ astro-ph.HEastro-ph.SRgr-qcnucl-thPRD(2025)·30 citations
05
Far-from-equilibrium attractors in kinetic theory with two different relaxation times
Ferdinando Frascà🇮🇹 · Andrea Beraudo🇮🇹 · Michael Strickland
We solve a Boltzmann equation for massless quark and gluon fluids in a transversally homogeneous, longitudinally boost-invariant expansion. Quarks can be out of chemical equilibrium and the relaxation times of the two species are assumed to be connected by Casimir scaling. We numerically calculate moments of the distribution functions, identifying their early- and late-time attractors and reconstructing also the full distributions. These attractors appear when the system is still far from local thermalization, before hydrodynamics traditionally would be expected to apply. We also analyze the evolution of entropy production for different initial momentum anisotropies and quark abundances.
↳ hep-phnucl-thPoS(2025)·0 citations
06
Mixing mechanism for the $J^{P} = 0^{+}$ mesons
Hungchong Kim🇰🇷 · K. S. Kim🇰🇷
There are three scalar nonets in the Particle Data Group (PDG), one of which includes [ $a_{0} (980), K_{0}^{*} (700)$ ], another includes [ $a_{0} (1450), K_{0}^{*} (1430)$ ], and the third includes [ $a_{0} (1710), K_{0}^{*} (1950)$ ]. Motivated by Ref.[1], we examine an alternative mixing mechanism that could potentially explain the small mass difference between the $a_{0} (1450)$ and $K_{0}^{*} (1430)$ . According to the tetraquark mixing model, two types, distinguished by their color-spin structures, are necessary to describe the tetraquark structure of the two nonets containing [ $a_{0} (980), K_{0}^{*} (700)$ ] and [ $a_{0} (1450), K_{0}^{*} (1430)$ ]. Considering the color-spin structures, we argue that the mixing mechanism generating $a_{0} (1450)$ and $K_{0}^{*} (1430)$ on the one hand, and $a_{0} (1710)$ and $K_{0}^{*} (1950)$ on the other hand might be relevant for resolving the small mass difference. We also discuss the limitations of other mixing mechanisms that generate the two nonets involving [ $a_{0} (980), K_{0}^{*} (700)$ ] and [ $a_{0} (1450)$ , $K_{0}^{*} (1430)$ ] or [ $a_{0} (980), K_{0}^{*} (700)$ ] and [ $a_{0} (1710)$ , $K_{0}^{*} (1950)$ ]
↳ hep-phhep-exnucl-thPRD(2025)·2 citations
07
Efficient simulation of quarkonium master equation beyond the dipole approximation
Jorge M. Mtz-Vera🇮🇹 · Andrea Beraudo🇮🇹 · Miguel Ángel Escobedo🇪🇸 · Paolo Parotto🇮🇹 · Michael Strickland
QTRAJ is a computer code that simulates the propagation of quarkonium in the quark-gluon plasma (QGP) based on the quantum-trajectory algorithm. This algorithm solves a master equation in which the quarkonium is treated as an open quantum system (OQS). A major advantage of this approach is that it turns a 3D spatial evolution for a density matrix into a 1D Schrödinger equation for a wavefunction with a non-hermitian Hamiltonian, drastically reducing the computational cost. So far, the interaction implemented in the master equation was obtained within the framework of potential non-relativistic QCD (pNRQCD), and restricted to the regime $r T ≪ 1$ , where $r$ is the size of the color dipole and $T$ is the temperature. In the environment produced in heavy-ion collisions (HIC's) this limit is accurate for $Υ (1 S)$ , but the applicability to other quarkonium states is dubious. In the present study we generalize the above approach, extending it to the regime $r T \sim 1$ in the one-gluon exchange approximation, with proper Hard Thermal Loop (HTL) resummation of medium effects. This is done by implementing new jump operators connecting different color states of the $Q Q ˉ$ pair and expanding them in plane waves, giving rise to a variation of the algorithm present in QTRAJ 1.0. Here we provide an overview of this approach comparing the $r T ≪ 1$ and $r T \sim 1$ cases, and we discuss prospects for phenomenological application to excited states of bottomonium.
↳ hep-phnucl-thPoS(2025)·2 citations
08
Transport coefficients of chiral fluid dynamics using low-energy effective models
Pedro Nogarolli🇧🇷 · Gabriel S. Denicol🇧🇷 · Eduardo S. Fraga🇧🇷
We investigate the first-order transport coefficients of a fluid made of quasiparticles with a temperature-dependent mass extracted from chiral models. We describe this system using an effective kinetic theory, given by the relativistic Boltzmann equation coupled to a temperature-dependent background field determined from the thermal masses. We then simplify the collision term using the relaxation time approximation and implement a Chapman-Enskog expansion to calculate all first-order transport coefficients. In particular, we compute the bulk and shear viscosities using thermal masses extracted from the linear sigma model coupled with constituent quarks and the NJL model.
↳ hep-phnucl-thPRD(2026)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

2+1 dimensional Floquet systems and lattice fermions: Exact bulk spectral equivalence

XTE J1814-338: A potential hybrid star candidate

Far-from-equilibrium attractors in kinetic theory with two different relaxation times

Mixing mechanism for the JP=0+ mesons

Efficient simulation of quarkonium master equation beyond the dipole approximation

Transport coefficients of chiral fluid dynamics using low-energy effective models

Affiliations

$2 + 1$ dimensional Floquet systems and lattice fermions: Exact bulk spectral equivalence

Mixing mechanism for the $J^{P} = 0^{+}$ mesons