Nuclear Theory·nucl-th

Thursday·June 29, 2023

9 papers—4 primary·5 cross-listed

01
A method for probing the formation of quark matter
Gao-Chan Yong🇨🇳
Based on a multi-phase transport model for relativistic heavy-ion collisions, effects of the parton scatterings on the production of strangeness in relativistic heavy-ion collisions are studied. It is found that the distributions of strange quark and strange baryon, especially for the double strangeness $Ξ^{-}$ , are significantly affected by the parton scatterings in heavy-ion collisions below $s_{N N} \sim$ 10 GeV. Given parton scatterings as a signal of the formation of quark matter, the transverse momentum distribution of the ratio of single and double strangeness $(Λ + Σ^{0}) / Ξ^{-}$ produced in heavy-ion collisions may serve as a potential probe of the emergence of quark matter, or equivalently, the occurrence of hadron-quark phase transition in relativistic heavy-ion collisions.
nucl-thnucl-exPLB(2023)·6 citations
02
Phase diagram determination at fivefold nuclear compression
Gao-Chan Yong🇨🇳
In the standard model of particle physics, the strong force is characterized by the theory of quantum chromodynamics (QCD). It is commonly understood from QCD properties that hadrons, at sufficiently high temperatures or densities, melt into their constituent quarks, thereby undergoing a deconfinement transition to a new phase of quarks and gluons, often referred to as quark matter or quark-gluon plasma (QGP) \cite{qcd00,qcd01}. Although QGP has been observed in relativistic heavy-ion collisions \cite{qgp1,qgp2}, uncertainties remain about when the onset of deconfinement occurs. After comparing simulations from a reliable hadron and quark relativistic transport model with recent data from the STAR experiment, we determined that the onset of the hadron-quark phase transition occurs at about five times nuclear compression, corresponding to temperature $T \sim$ 112 MeV and baryon chemical potential $μ_{B} \sim$ 586 MeV, in the nuclear matter phase diagram. This discovery has significant implications for the studies of both the early and present universe \cite{ann2006}, including the fraction of dark matter formed in the early universe \cite{bhd2016,bhf1997,pbh20} and the structure and dynamics of neutron stars and their mergers \cite{nature2020}.
nucl-thnucl-exPLB(2024)·10 citations
03
Missed prediction of the neutron halo in $^{37}$ Mg
K. Y. Zhang · S. Q. Yang · J. L. An · S. S. Zhang · P. Papakonstantinou · M.-H. Mun · Y. Kim · H. Yan
Halo phenomena have long been an important frontier in both experimental and theoretical nuclear physics. $^{37}$ Mg was identified as a halo nucleus in 2014 and remains the heaviest nuclear halo system to date. While the halo phenomenon in $^{37}$ Mg was not predicted before the discovery, its description has been still challenging afterwards. In this Letter, we report a microscopic and self-consistent description of the neutron halo in $^{37}$ Mg using the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) that was developed in 2010. The experimental neutron separation energies and empirical matter radii of neutron-rich magnesium isotopes as well as the deformed $p$ -wave halo characteristics of $^{37}$ Mg are well reproduced without any free parameters. In particular, the orbital occupied by the halo neutron in $^{37}$ Mg, exhibiting $p$ -wave components comparable to those suggested in experiments, remains consistent across various employed density functionals including PC-F1, PC-PK1, NL3*, and PK1. The DRHBc theory investigated only even-even magnesium isotopes in previous works and for that reason missed predicting $^{37}$ Mg as a halo nucleus before 2014. Although the core and the halo of $^{37}$ Mg are both prolate, higher-order shape decoupling on the hexadecapole and hexacontatetrapole levels is predicted.
nucl-thPLB(2023)·48 citations
04
Neutrino spectrum and energy loss rates due to weak processes on hot $^{56}$ Fe in pre-supernova environment
Alan A. Dzhioev · A. V. Yudin · N. V. Dunina-Barkovskaya · A. I. Vdovin
Applying TQRPA calculations of Gamow--Teller strength functions in hot nuclei, we compute the (anti)neutrino spectra and energy loss rates arising from weak processes on hot $^{56}$ Fe under pre-supernova conditions. We use a realistic pre-supernova model calculated by the stellar evolution code MESA. Taking into account both charged and neutral current processes, we demonstrate that weak reactions with hot nuclei can produce high-energy (anti)neutrinos. We also show that, for hot nuclei, the energy loss via (anti)neutrino emission is significantly larger than that for nuclei in their ground state. It is found that the neutral current de-excitation via the $ν ν ˉ$ -pair emission is presumably a dominant source of antineutrinos. In accordance with other studies, we confirm that the so-called single-state approximation for neutrino spectra might fail under certain pre-supernova conditions. }
nucl-thastro-ph.SRParticles(2023)·8 citations
05
Universal rapidity scaling of entanglement entropy inside hadrons from conformal invariance
Umut Gürsoy🇳🇱 · Dmitri E. Kharzeev🇺🇸 · Juan F. Pedraza🇪🇸
When a hadron is probed at high energy, a nontrivial quantum entanglement entropy inside the hadron emerges due to the lack of complete information about the hadron wave function extracted from this measurement. In the high-energy limit, the hadron becomes a maximally entangled state, with a linear dependence of entanglement entropy on rapidity, as has been found in a recent analysis based on parton description. In this paper, we use an effective conformal field theoretic description of hadrons on the light cone to show that the linear dependence of the entanglement entropy on rapidity found in parton description is a general consequence of approximate conformal invariance and does not depend on the assumption of weak coupling. Our result also provides further evidence for a duality between the parton and string descriptions of hadrons.
↳ hep-thhep-phnucl-thPRD(2024)·18 citations
06
Intruder configurations in $^{29}$ Ne at the transition into the island of inversion: Detailed structure study of $^{28}$ Ne
H.Wang · M.Yasuda · Y.Kondo · T.Nakamura · J.A. Tostevin · K.Ogata · T.Otsuka · A.Poves · N.Shimizu · K.Yoshida · N.L.Achouri · H.Al Falou and 84 other authors
Detailed $γ$ -ray spectroscopy of the exotic neon isotope $^{28}$ Ne has been performed for the first time using the one-neutron removal reaction from $^{29}$ Ne on a liquid hydrogen target at 240~MeV/nucleon. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for $^{28}$ Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder $p$ -wave strength providing evidence of the breakdown of the $N = 20$ and $N = 28$ shell gaps. Only a weak, possible $f$ -wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large $p$ -wave and small $f$ -wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.
↳ nucl-exnucl-thPLB(2023)·6 citations
07
Schwinger poles of the three-gluon vertex: symmetry and dynamics
A. C. Aguilar🇧🇷 · M. N. Ferreira🇪🇸 · B. M. Oliveira🇧🇷 · J. Papavassiliou🇪🇸 · L. R. Santos🇧🇷
The implementation of the Schwinger mechanism endows gluons with a nonperturbative mass through the formation of special massless poles in the fundamental QCD vertices; due to their longitudinal character, these poles do not cause divergences in on-shell amplitudes, but induce detectable effects in the Green's functions of the theory. Particularly important in this theoretical setup is the three-gluon vertex, whose pole content extends beyond the minimal structure required for the generation of a gluon mass. In the present work we analyze these additional pole patterns by means of two distinct, but ultimately equivalent, methods: the Slavnov-Taylor identity satisfied by the three-gluon vertex, and the nonlinear Schwinger-Dyson equation that governs the dynamical evolution of this vertex. Our analysis reveals that the Slavnov-Taylor identity imposes strict model-independent constraints on the associated residues, preventing them from vanishing. Approximate versions of these constraints are subsequently recovered from the Schwinger-Dyson equation, once the elements responsible for the activation of the Schwinger mechanism have been duly incorporated. The excellent coincidence between the two approaches exposes a profound connection between symmetry and dynamics, and serves as a nontrivial self-consistency test of this particular mass generating scenario.
↳ hep-phhep-lathep-thnucl-thEPJC(2023)·8 citations
08
Inhomogeneous condensation in the Gross-Neveu model in noninteger spatial dimensions $1 \leq d < 3$
Laurin Pannullo🇩🇪
The Gross-Neveu model in the $N \to \infty$ approximation in $d = 1$ spatial dimensions exhibits a chiral inhomogeneous phase (IP), where the chiral condensate has a spatial dependence that spontaneously breaks translational invariance and the $Z_{2}$ chiral symmetry. This phase is absent in $d = 2$ , while in $d = 3$ its existence and extent strongly depends on the regularization and the value of the finite regulator. This work connects these three results smoothly by extending the analysis to non-integer spatial dimensions $1 \leq d < 3$ , where the model is fully renormalizable. To this end, we adapt the stability analysis, which probes the stability of the homogeneous ground state under inhomogeneous perturbations, to non-integer spatial dimensions. We find that the IP is present for all $d < 2$ and vanishes exactly at $d = 2$ . Moreover, we find no instability towards an IP for $2 \leq d < 3$ , which suggests that the IP in $d = 3$ is solely generated by the presence of a regulator.
↳ hep-phcond-mat.str-elnucl-thPRD(2023)·18 citations
09
Corrections to the Forward Limit Dispersion Relations for $γ Z$ -Exchange Contributions
Qian-Qian Guo🇨🇳 · Hai-Qing Zhou🇨🇳
The weak charge of the proton $Q_{w}$ is one of the most fundamental quantities in physics. It can be determined by measuring the parity asymmetry $A_{PV}$ in elastic $e p$ scattering, where the $γ Z$ -exchange contributions are crucial. For the past fifteen years, dispersion relations (DRs) in the forward limit have been widely used as a model-independent method to estimate these contributions. In this work, we study corrections to these forward-limit DRs. We first estimate these corrections using pointlike interactions as an illustrative example. We then estimate the $γ Z$ -exchange contributions for the upcoming P2 experiment through both direct calculation and the forward-limit DRs, within the framework of low-energy effective interactions. The results indicate that the correction to the forward-limit DR for $□_{γ Z}^{V}$ is around 47\% for the upcoming P2 experiment, which will significantly modify the extracted value of $Q_{w}$ .
↳ hep-phnucl-exnucl-thPRC(2024)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE