Nuclear Theory·nucl-th

Tuesday·February 27, 2024

13 papers—8 primary·5 cross-listed

01
[Submitted on 23 Feb 2024]
General predictions of neutron star properties using unified relativistic mean-field equations of state
Luigi Scurto🇵🇹 · Helena Pais🇵🇹 · Francesca Gulminelli🇫🇷
In this work we present general predictions for the static observables of neutron stars (NSs) under the hypothesis of a purely nucleonic composition of the ultra-dense baryonic matter, using Bayesian inference on a very large parameter space conditioned by both astrophysical and nuclear physics constraints. The equation of states are obtained using a unified approach of the NS core and inner crust within a fully covariant treatment based on a relativistic mean-field Lagrangian density with density dependent couplings. The posterior distributions are well compatible with the ones obtained by semi-agnostic meta-modelling techniques based on non-relativistic functionals, that span a similar portion of the parameter space in terms of nuclear matter parameters, and we confirm that the hypothesis of a purely nucleonic composition is compatible with all the present observations. We additionally show that present observations do not exclude the existence of very massive neutron stars with mass compatible with the lighter partner of the gravitational event GW190814 measured by the LIGO-Virgo collaboration. Some selected representative models, that respect well all the constraints taken into account in this study, and approximately cover the residual uncertainty in our posterior distributions, will be uploaded in the CompOSE database for use by the community.
Comments:
28 pages, 21 figures, 9 tables. Submitted to Phys. Rev. D
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2402.15548 [pdf]
PRD(2024)·32 citations
02
[Submitted on 23 Feb 2024]
Shell-model study of $^{58}$ Ni using quantum computing algorithm
Bharti Bhoy🇬🇧 · Paul Stevenson🇬🇧
This study presents a simulated quantum computing approach for the investigation into the shell-model energy levels of $^{58}$ Ni through the application of the variational eigensolver (VQE) method in combination with a problem-specific ansatz. The primary objective is to achieve a fully accurate low-lying energy spectrum of $^{58}$ Ni. The chosen isotope, $^{58}$ Ni is particularly interesting in nuclear physics through its role in astrophysical reactions while also being a simple but not-trivial nucleus for shell-model study, it being two particles outside a closed shell. Our ansatz, along with the VQE method are shown to be able to reproduce exact energy values for the ground state and first and second excited states. We compare a classical shell model code, the values obtained by diagonalization of the Hamiltonian after qubit mapping, and a noiseless simulated ansatz+VQE simulation. The exact agreement between classical and qubit-mapped diagonalisation shows the correctness of our method, and the high accuracy of the simulation means that the ansatz is suitable to allow a full reconstruction of the full nuclear wave function.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2402.15577 [pdf]
New J.Phys.(2024)·31 citations
03
[Submitted on 24 Feb 2024]
Ab initio description of monopole resonances in light- and medium-mass nuclei: II. Ab initio PGCM calculations in $^{46}$ Ti, $^{28}$ Si and $^{24}$ Mg
Andrea Porro🇩🇪 · Thomas Duguet🇫🇷 · Jean-Paul Ebran🇫🇷 · Mikael Frosini🇫🇷 · Robert Roth🇩🇪 · Vittorio Somà🇫🇷
Giant resonances (GRs) are a striking manifestation of collective motions in atomic nuclei. The present paper is the second in a series of four dedicated to the use of the projected generator coordinate method (PGCM) for the ab initio determination of the isoscalar giant monopole resonance (GMR) in closed- and open-shell mid-mass nuclei. While the first paper was dedicated to quantifying various uncertainty sources, the present paper focuses on the first applications to three doubly-open shell nuclei, namely $^{46}$ Ti, $^{28}$ Si and $^{24}$ Mg. In particular, the goal is to investigate from an ab initio standpoint (i) the coupling of the GMR with the giant quadrupole resonance (GQR) in intrinsically-deformed nuclei, (ii) the possible impact of shape coexistence and shape mixing on the GMR, (iii) the GMR based on shape isomers and (iv) the impact of anharmonic effects on the monopole response. The latter is studied by comparing PGCM results to those obtained via the quasi-particle random phase approximation (QRPA), the traditional many-body approach to giant resonances, performed in a consistent setting. Eventually, PGCM results for sd-shell nuclei are in excellent agreement with experimental data, which is attributed to the capacity of the PGCM to capture the important fragmentation of the monopole response in light, intrinsically-deformed systems. Still, the comparison to data in $^{28}$ Si and $^{24}$ Mg illustrates the challenge (and the potential benefit) of extracting unambiguous experimental information.
Comments:
19 pages, 27 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2402.15901 [pdf]
EPJA(2024)·19 citations
04
[Submitted on 25 Feb 2024]
Transport properties of asymmetric nuclear matter in the spinodal region
Lei-Ming Hua🇨🇳 · Jun Xu🇨🇳
We have studied the shear and bulk viscosities of asymmetric nuclear matter in the mechanical and chemical instability region based on IBUU transport simulations in a box system. The Green-Kubo method is used to calculate these viscosities with a prepared dynamically equilibrated nuclear system with hot clusters. While the behavior of the shear viscosity is largely affected by energy-dependent nucleon-nucleon cross sections, the bulk viscosity increases significantly in the presence of nuclear clusters compared to that in uniform nuclear matter. Increasing isospin asymmetry generally increases both viscosities, while their behaviors are qualitatively modified once the isospin asymmetry is large enough to affect significantly the spinodal region. Our calculation shows that the bulk viscosity is more sensitive to the nuclear clustering than the shear viscosity, and is thus a robust quantity related to the phase diagram of asymmetric nuclear matter.
Comments:
8 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2402.15963 [pdf]
PRC(2024)·1 citation
05
[Submitted on 25 Feb 2024]
Microscopic study of deformation and orientation effects in heavy-ion reactions above Coulomb barrier using the Boltzmann-Uehling-Uhlenbeck model
Yujie Feng · Huizi Liu · Yingge Huang · Fuchang Gu · Erxi Xiao · Xin Lei · Hui Wang · Jiali Huang · Long Zhu · Jun Su
Background: The understanding of the impact of initial deformation and collision orientation on quasi-fission and fusion-fission reactions remains incomplete. Purpose: This article aims to explore how the orientation of deformed nuclei influences quasi-fission and fusion-fission around 1.2 VB, employing a micro dynamical method in systems with diverse shapes, namely 24Mg + 178Hf, 34S + 168Er, and 48Ti + 154Sm. Method: Utilizing the Boltzmann-Uehling-Uhlenbeck model, this study investigates quasi-fission and fusion fission reactions. The model elucidates micro-dynamic processes and microscopic observables through the definition of the window and event-by-event simulations. Results: The findings reveal that the orientation of deformed nuclei significantly influences the nucleus-nucleus interaction potential, thereby impacting the competition between quasi-fission and fusion-fission. Particularly, the orientation of the deformed target nucleus emerges as the primary factor affecting this competition. Notably, a higher proportion of fusion-fission events is observed when the target nucleus is in the belly orientation compared to the tip. The study also observes that the configuration of the dinuclear system contributes to fluctuations and dissipation. Collisions with different orientations result in distinct dinuclear system configurations, with belly-oriented collisions leading to larger fluctuations between events, while tip-oriented collisions exhibit smaller fluctuations. Conclusions: Considering diverse orientations of nuclei with distinct initial deformations, this study concludes that the orientation of the target nucleus is the key factor influencing quasi-fission and fusion-fission reactions around 1.2 VB.
Comments:
9 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2402.16019 [pdf]
PRC(2024)·3 citations
06
[Submitted on 26 Feb 2024]
Microscopic optical potential from the relativistic Brueckner-Hartree-Fock theory: Proton-nucleus scattering
Pianpian Qin🇨🇳 · Sibo Wang🇨🇳 · Hui Tong🇩🇪 · Qiang Zhao🇰🇷 · Chencan Wang🇨🇳 · Z. P. Li🇨🇳 · Peter Ring🇩🇪
A relativistic microscopic optical model potential for nucleon-nucleus scattering is developed based on the \emph{ab initio} relativistic Brueckner-Hartree-Fock (RBHF) theory with the improved local density approximation, which is abbreviated as the RBOM potential. Both real and imaginary parts of the single-particle potentials in symmetric and asymmetric nuclear matter at various densities are determined uniquely in the full Dirac space. The density distributions of the target nuclei are calculated by the covariant energy density functional theory with the density functional PC-PK1. The central and spin-orbit terms of the optical potentials are quantitatively consistent with the relativistic phenomenological optical potentials. The performance of the RBOM potential is evaluated by considering proton scattering with incident energy $E \leq 200$ MeV on five target nuclei, $\prescript 208 Pb$ , $\prescript 120 Sn$ , $\prescript 90 Zr$ , $\prescript 48 Ca$ , and $\prescript 40 Ca$ . Scattering observables including the elastic scattering angular distributions, analyzing powers, spin rotation functions, and reaction cross sections are analyzed. Theoretical predictions show good agreements with the experimental data and the results derived from phenomenological optical potentials. We anticipate that the RBOM potential can provide reference for other phenomenological and microscopic optical model potentials, as well as reliable descriptions for nucleon scattering on exotic nuclei in the era of rare-isotope beams.
Comments:
36 pages, 20 figures, published as Phys. Rev. C 109, 064603 (2024), Editor's Suggestion
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2402.16339 [pdf]
PRC(2024)·13 citations
07
[Submitted on 26 Feb 2024]
Shell-model study of $lo g f t$ values for $^{139, 140, 141}$ Ba $\to$ $^{139, 140, 141}$ La transitions
Shweta Sharma · Praveen C. Srivastava
In the present work, beta-decay properties such as $lo g f t$ values and half-lives have been systematically studied corresponding to Ba isotopes using large-scale shell-model calculations. An extensive comparison of beta decay results corresponding to $^{141}$ Ba $\to$ $^{141}$ La using shell-model calculations is made with the recently available experimental data. In addition, we have also calculated the nuclear and beta decay properties corresponding to $^{139}$ Ba $\to$ $^{139}$ La and $^{140}$ Ba $\to$ $^{140}$ La transitions. The model-space considered here is $Z = 50 - 82$ and $N = 82 - 126$ with $^{132}$ Sn core, and the interaction employed here is jj56pnb interaction. The beta decay results using shell-model calculations for all the mentioned isotopes are compared with the available experimental data. This is the first theoretical interpretation corresponding to recent experimental data.
Comments:
26 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2402.16502 [pdf]
NPA(2024)·1 citation
08
[Submitted on 26 Feb 2024]
Hexadecapole deformation of $^{238}$ U from relativistic heavy-ion collisions using a nonlinear response coefficient
Hao-jie Xu🇨🇳 · Jie Zhao🇨🇳 · Fuqiang Wang🇨🇳
The hexadecapole deformation ( $β_{4}$ ) of the $^{238}$ U nucleus has not been determined because its effect is overwhelmed by those from the nucleus' large quadrupole deformation ( $β_{2}$ ) in nuclear electric transition measurements. In this Letter, we identify the nonlinear response of the hexadecapole anisotropy to ellipticity in relativistic $^{238}$ U+ $^{238}$ U collisions that is solely sensitive to $β_{4}$ and insensitive to $β_{2}$ . We demonstrate this by state-of-the-art hydrodynamic calculations and discuss the prospects of discovering the $β_{4}$ of $^{238}$ U in heavy-ion data at the Relativistic Heavy Ion Collider.
Comments:
7 pages, 3 figures, published version
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2402.16550 [pdf]
PRL(2024)·36 citations

Affiliations

first authorsco-authorsvia INSPIRE