Nuclear Theory·nucl-th

Friday·October 25, 2024

8 papers—2 primary·6 cross-listed

01
[Submitted on 24 Oct 2024]
Effects of incompressibility on the neutron-proton equilibration in $^{70}$ Zn + $^{70}$ Zn collisions at 35 MeV/nucleon
Erxi Xiao · Yu Yang · Yingge Huang · Zhen Zhang · Long Zhu · Jun Su
Background: The primary goal of studying isospin dynamics via heavy-ion reactions is to explore the isospin dependence of effective interactions within the nuclear equation of state (EOS). Purpose: This work aims to investigate the effects of nuclear incompressibility ( $K_{0}$ ) on neutron-proton equilibration in projectile-like fragments (PLFs). Method: We simulate $^{70}$ Zn + $^{70}$ Zn collisions at 35 MeV/nucleon using the isospin-dependent quantum molecular dynamics (IQMD) model, coupled with the statistical decay code GEMINI. Results: The IQMD simulations not only reproduce experimental data patterns but also reveal the dynamic mechanisms underlying the binary breakup of PLFs. The rotation of PLFs is influenced by the transformation of angular momentum, which is connected to the isoscalar component of the EOS. This connection explains why shifts in $K_{0}$ affect the description of neutron-proton equilibration as measured by PLF rotation. The simulations demonstrate that a model with a smaller $K_{0}$ paired with a softer symmetry energy, or a larger $K_{0}$ with a slightly stiffer symmetry energy, both offer better indications of neutron-proton equilibration. Conclusion: Considering the uncertainty in $K_{0}$ , the slope of the symmetry energy is constrained within the range of $L = 20 \sim 40$ MeV, providing valuable insights into the nuclear equation of state.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2410.18569 [pdf]
PRC(2025)·0 citations
02
[Submitted on 24 Oct 2024]
Impact of ground-state properties and collective excitations on the Skyrme ansatz: a Bayesian study
Pietro Klausner🇮🇹 · Gianluca Colò🇮🇹 · Xavier Roca-Maza🇮🇹 · Enrico Vigezzi🇮🇹
State-of-the-art models based on nuclear Density Functional Theory are successful in the description of nuclei throughout the whole nuclear chart. Among them, some differences arise regarding their accuracy. For a given nuclear model, this depends on the procedure adopted to determine the parameters, and, at the same time, new experimental findings constantly challenge theory. In the present work, we present a Bayesian inference study aimed at assessing the performance of the Skyrme Energy Density Functional. For the sake of simplicity and clarity, we restrict to spherical, double-magic nuclei, giving equal emphasis to ground-state and dynamical properties. Our basic constraints are: i) masses and charge radii, which are known to be very sensitive to the saturation energy and density; ii) spin-orbit splittings, which are associated with the spin-orbit parameter(s); iii) the electric dipole polarizability and parity-violating asymmetry, which are associated with the density dependence of the symmetry energy; iv) the excitation energy of the Isoscalar Giant Monopole Resonance, to constrain the nuclear matter incompressibility; v) the energy-weighted sum rule of the Isovector Giant Dipole Resonance, to account for the isovector effective mass; and vi) the excitation energy of the Isoscalar Quadrupole Resonance, that is related to the isoscalar effective mass. In this way, we test the Skyrme ansatz in a statistically meaningful way, by determining the posterior distributions of the parameters as well as their correlation, and discussing a possible strategy for future developments.
Comments:
15 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2410.18598 [pdf]
PRC(2025)·12 citations
03
[Submitted on 23 Oct 2024] (cross-list from quant-ph)
$2 + 1$ 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.
Comments:
11 figures
Subjects:
Quantum Physics (quant-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2410.18226 [pdf]
SciPost Phys.Core(2025)·1 citation
04
[Submitted on 24 Oct 2024] (cross-list from astro-ph.HE)
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.
Comments:
v1: 7 pages, 5 figures; v2: 7 pages, 5 figures, 1 table; v3: 8 pages, 5 figures, 1 table; updated to match the published version; accepted for publication in Physical Review D
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2410.18498 [pdf]
PRD(2025)·30 citations
05
[Submitted on 24 Oct 2024] (cross-list from hep-ph)
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.
Comments:
Proceeedings of the 10th International Conference on Quarks and Nuclear Physics (QNP2024)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2410.18566 [pdf]
PoS(2025)·0 citations
06
[Submitted on 24 Oct 2024] (cross-list from hep-ph)
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 [ $a_{0} (1710)$ , $K_{0}^{*} (1950)$ ]
Comments:
9 pages, 1 figure. Some changes have been made, including additional references. This is the accepted version to appear in Physical Review D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2410.18589 [pdf]
PRD(2025)·2 citations
07
[Submitted on 24 Oct 2024] (cross-list from hep-ph)
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.
Comments:
Proceedings of the Conference QNP 2024
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2410.18709 [pdf]
PoS(2025)·2 citations
08
[Submitted on 24 Oct 2024] (cross-list from hep-ph)
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.
Comments:
11 pages, 17 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2410.18791 [pdf]
PRD(2026)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE