Nuclear Theory·nucl-th

Tuesday·June 18, 2024

14 papers—9 primary·5 cross-listed

01
[Submitted on 15 Jun 2024]
Role of the symmetry energy slope in neutron stars: exploring the model-dependency
Luiz L. Lopes🇧🇷
Using six different parametrizations of the quantum hadrodynamics (one of which is original), I study how different values of the symmetry energy slope ( $L)$ affect some microscopic and macroscopic properties of neutron stars, such as the proton fraction, the maximum mass, the radius of the canonical 1.4 $M_{⊙}$ star and its dimensionless tidal parameter $Λ$ . I show that while most quantities present the same qualitative results, the tidal parameter can increase or decrease with the slope, depending on the model. Moreover, special attention is given to the minimum mass that enables the direct URCA process to occur in neutron stars' interiors ( $M_{D U})$ . Assuming the weak constraint $M_{D U} > 1.35 M_{⊙}$ , we see that the maximum value of $L$ that satisfies it lies between 79 and 86 MeV. A range of only 7 MeV. Therefore, $M_{D U}$ is an easy way to impose upper bounds to the slope.
Comments:
7 pages + Appendix. Similar to the published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2406.10755 [pdf]
PRC(2024)·16 citations
02
[Submitted on 16 Jun 2024]
Odd-even mass differences of well and rigidly deformed nuclei in the rare earth region: A test of a newly proposed fit of average pairing matrix elements
T. V. Nhan Hao🇻🇳 · N. N. Bao Nguyen🇻🇳 · D. Quang Tam🇻🇳 · P. Quentin🇫🇷 · Meng-Hock Koh🇫🇷 · L. Bonneau🇲🇾
We discuss a test of a recently proposed approach to determine average pairing matrix elements within a given interval of single-particle states (sp) around the Fermi level $λ$ as obtained in the so-called uniform gap method (UGM). It takes stock of the crucial role played by the averaged sp level density $ρ ~ (e)$ . These matrix elements are deduced within the UGM approach, from microscopically calculated $ρ ~ (e)$ and gaps obtained from analytical formulae of a semi-classical nature. Two effects generally ignored in similar fits have been taken care of. They are: (a) the correction for a systematic bias in choosing to fit pairing gaps corresponding to equilibrium deformation solutions as discussed by Möller and Nix [Nucl. Phys. A 476, 1 (1992)] and (b) the correction for a systematic spurious enhancement of $ρ ~ (e)$ for protons in the vicinity of $λ$ , because of the local Slater approximation used for the treatment of the Coulomb exchange terms in most calculations (see e.g. [Phys. Rev C 84, 014310 (2011)]). This approach has been deemed to be very efficient upon performing Hartree-Fock + BCS (with seniority force and self-consistent blocking when dealing with odd nuclei) calculations of a large sample of well and rigidly deformed even-even rare-earth nuclei. The reproduction of their experimental moments of inertia has been found to be at least of the same quality as what has been obtained in a direct fit of these data [Phys. Rev C 99, 064306 (2019)]. We extend here the test of our approach to the reproduction, in the same region, of three-point odd-even mass differences centered on odd- $N$ or odd- $Z$ nuclei. The agreement with the data is again roughly of the same quality as what has been obtained in a direct fit, as performed in [Phys. Rev C 99, 064306 (2019)].
Comments:
3 tables, submitted to Chinese Physics C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2406.10783 [pdf]
CPC(2025)·1 citation
03
[Submitted on 16 Jun 2024]
Density-dependent relativistic mean-field model for $Ξ^{-}$ hypernuclei
Shi Yuan Ding🇨🇳 · Ting-Ting Sun🇨🇳 · Bao Yuan Sun🇨🇳
In hypernuclear systems, interactions involving nucleons and hyperons are intricately influenced by the surrounding particles, particularly by the density and the isospin feature of the nuclear medium. In this work, the relativistic mean-field (RMF) theory is adopted to describe the structure of several typical $Ξ^{-}$ hypernuclei. New sets of $Ξ N$ effective interactions, by taking a density-dependent meson-nucleon/hyperon coupling perspective, are developed by fitting experimental data on the $Ξ^{-}$ hyperon $1 s$ and $1 p$ state separation energy of $_{Ξ^{-}}^{15}$ C as well as the $1 p$ state separation energy of $_{Ξ^{-}}^{13}$ B. The density-dependent behavior of meson-hyperon coupling strengths sensitively affects the description of hyperon single-particle levels. In fact, the density-dependent meson-baryon coupling strengths introduce additional rearrangement contributions to the hyperon self-energy. Correspondingly, detailed forms of density dependence in these coupling strengths and different considerations of meson-baryon coupling channels will impact the hyperon single-particle properties within hypernuclei. Especially with the additional inclusion of the isovector scalar $δ$ meson, the significant enhancement of rearrangement terms in the effective interaction DD-ME $δ$ impacts the shape of the hyperon potential and alters the characteristics of the isovector channel dynamics balance in the effective nuclear force. Relevant research underscores the importance of precisely accounting for in-medium effects in hyperon-nucleon interactions and incorporating a more comprehensive set of meson-exchange degrees of freedom in effective nuclear forces, offering a potential solution for more self-consistently describing the featured hyperon single-particle behavior of various hypernuclei and for reducing uncertainties in theoretical descriptions.
Comments:
13 pages, 4 figures, 4 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2406.10980 [pdf]
PRC(2025)·7 citations
04
[Submitted on 16 Jun 2024]
Exact solution of the nonlinear boson diffusion equation for gluon scattering
L. Möhringer🇩🇪 · G. Wolschin🇩🇪
An exact analytical solution of the nonlinear boson diffusion equation (NBDE) is presented. It accounts for the time evolution towards the Bose-Einstein equilibrium distribution through inelastic and elastic collisions in case of constant transport coefficients. As a currently interesting application, gluon scattering in relativistic heavy-ion collisions is investigated. An estimate of time-dependent gluon-condensate formation in overoccupied systems through number-conserving elastic scatterings in Pb-Pb collisions at relativistic energies is given.
Comments:
16 pages, 2 figures; submitted to J. Stat. Mech.: Theory and Experiment (IOP/SISSA)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); nlin.SI (nlin.SI)
arXiv:
2406.11017 [pdf]
J.Stat.Mech.(2024)·0 citations
05
[Submitted on 17 Jun 2024]
$B_{c}^{\pm}$ - $^{12}$ C states and detailed study of momentum space method for $Υ$ - and $η_{b}$ -nucleus bound states
G. N. Zeminiani🇧🇷 · J. J. Cobos-Martínez🇲🇽 · K. Tsushima🇧🇷
We perform a detailed study of the $Υ$ -, $η_{b}$ -, and $B_{c}$ -nucleus systems in momentum space to calculate the bound-state energies and the corresponding coordinate-space radial wave functions. The attractive strong potentials for the meson-nucleus systems are calculated from the Lorentz scalar mass modifications of these mesons in nuclear matter in the local density approximation in the nucleus. The downward shift of the meson masses may be regarded as a signature of partial restoration of chiral symmetry in a nuclear medium applied in the present study in an empirical sense, because the origin of the negative mass shift in this study is not directly related to the chiral symmetry mechanism. Furthermore, as an initial and realistic study, the $B_{c}^{\pm}$ - $^{12}$ C bound states are studied for the first time, with the effects of self-consistently calculated Coulomb potentials in $^{12}$ C (when the $B_{c}^{\pm}$ mesons are absent).
Comments:
25 pages, 29 figures (77 .eps files for figures), changes: 6 figures added, appendix added
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2406.11114 [pdf]
PRC(2025)·5 citations
06
[Submitted on 17 Jun 2024]
Time-dependent density functional theory study of induced-fission dynamics of $^{226}$ Th
B. Li · D. Vretenar · T. Nikšić · P. W. Zhao · J. Meng
A microscopic finite-temperature model based on time-dependent nuclear density functional theory (TDDFT), is employed to study the induced-fission process of $^{226}$ Th. The saddle-to-scission dynamics of this process is explored, starting from various points on the deformation surface of Helmholtz free energy at a temperature that corresponds to the experimental excitation energy, and following self-consistent isentropic fission trajectories as they evolve toward scission. Dissipation effects and the formation of excited fragments are investigated and, in particular, the difference in the evolution of the local temperature along asymmetric and symmetric fission trajectories. The relative entropies and entanglement between fission fragments emerging at scission are analyzed.
Comments:
23 pages, 5 figures. arXiv admin note: text overlap with arXiv:2209.02419
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2406.11124 [pdf]
PRC(2024)·7 citations
07
[Submitted on 17 Jun 2024]
Investigating the excitation function of HBT radii for Lévy-stable sources
Mate Csanad🇭🇺 · Daniel Kincses🇭🇺
Contemporary heavy-ion physics research aims to explore the phase diagram of strongly interacting matter and search for signs of the possible critical endpoint on the QCD phase diagram. Femtoscopy is among the important tools used for this endeavor; there have been indications that combinations of femtoscopic radii parameters (referred to as HBT radii for identical boson pairs) can be related to the system's emission duration. An apparent non-monotonic behavior in their excitation function thus might signal the location of the critical point. In this paper, we show that conclusions drawn from the results obtained with a Gaussian approximation for the pion source shape might be altered if one utilizes a more general Lévy-stable source description. We find that the characteristic size of the pion source function is strongly connected to the shape of the source and its possible power-law behavior. Taking this into account properly changes the observed behavior of the excitation function.
Comments:
13 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2406.11435 [pdf]
J.Phys.G(2025)·8 citations
08
[Submitted on 17 Jun 2024]
Low Energy Nuclear Reactions Through Weak Interactions
K. Ramkumar · Harishyam Kumar · Pankaj Jain
We consider the possibility that low-energy nuclear reactions (LENR) arise due to the conversion of proton to neutron through weak interactions. The resulting neutron forms a short-lived virtual state, which then gets captured by another nucleus through photon emission. This whole process happens under the framework of second-order perturbation theory. We find that the rate of this process is negligibly small in most cases. However, in the presence of a resonance, the rate can be substantial and observable.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2406.11550 [pdf]
PRC(2024)·5 citations
09
[Submitted on 17 Jun 2024]
Four-dimensional QCD equation of state with multiple chemical potentials
Akihiko Monnai🇯🇵 · Grégoire Pihan🇺🇸 · Björn Schenke🇺🇸 · Chun Shen🇺🇸
We construct a four-dimensional version of the equation of state (EoS) model NEOS, NEOS-4D, as a function of the temperature and chemical potentials of baryon, electric charge, and strangeness for the hot and dense QCD matter created in relativistic nuclear collisions. This EoS enables multiple conserved charge current evolution in a relativistic fluid. Input from Lattice QCD simulations and a hadron resonance gas model is considered for constructing the equation of state. We investigate its applicability to the relativistic hydrodynamic description of nuclear collisions and present a method for efficient numerical implementation.
Comments:
11 pages, 9 figures; revised version to appear in Physical Review C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2406.11610 [pdf]
PRC(2024)·26 citations

Affiliations

first authorsco-authorsvia INSPIRE