Nuclear Theory·nucl-th

Tuesday·November 16, 2021

16 papers—10 primary·6 cross-listed

01
[Submitted on 13 Nov 2021]
Isoscalar giant monopole resonance in $^{24}$ Mg and $^{28}$ Si: Effect of coupling between the isoscalar monopole and quadrupole strength
A. Bahini (1 and 2) · V. O. Nesterenko (3, 4 and 5) · I. T. Usman (1) P. von Neumann-Cosel (6) · R. Neveling (2) · J. Carter (1) · J. Kvasil (7) · A. Repko (7 and 8) · P. Adsley (1, 2, 9 and 10) · N. Botha (1) · J. W. Brummer (2, 9) · L. M. Donaldson (2) · S. Jongile (2 and 9) and 14 other authors
Background: In highly deformed nuclei, there is a noticeable coupling of the Isoscalar Giant Monopole Resonance (ISGMR) and the $K = 0$ component of the Isoscalar Giant Quadrupole Resonance (ISGQR), which results in a double peak structure of the isoscalar monopole (IS0) strength (a narrow low-energy deformation-induced peak and a main broad ISGMR part). The energy of the narrow low-lying IS0 peak is sensitive to both the incompressibility modulus $K_{\infty}$ and the coupling between IS0 and isoscalar quadrupole (IS2) strength. Objective: This study aims to investigate the two-peaked structure of the ISGMR in the prolate $^{24}$ Mg and oblate $^{28}$ Si nuclei and identify among a variety of energy density functionals based on Skyrme parameterisations the one which best describes the experimental data. This will allow for conclusions regarding the nuclear incompressibility. Because of the strong IS0/IS2 coupling, the deformation splitting of the ISGQR will also be analysed. Methods: The ISGMR was excited in $^{24}$ Mg and $^{28}$ Si using $α$ -particle inelastic scattering measurements acquired with an $E_{α} = 196$ MeV beam at scattering angles $θ_{Lab} = 0^{\circ}$ and $4^{\circ}$ . The K $600$ magnetic spectrometer at iThemba LABS was used to detect and momentum analyse the inelastically scattered $α$ particles. An experimental energy resolution of $\approx 70$ keV (FWHM) was attained, revealing fine structure in the excitation-energy region of the ISGMR. The IS0 strength distributions in the nuclei studied were obtained with the Difference-of-Spectrum (DoS) technique. The theoretical comparison is based on the quasiparticle random-phase approximation (QRPA) with a representative set of Skyrme forces.
Comments:
17 pages, 16 figures, regular article
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2111.07105 [pdf]
PRC(2022)·17 citations
02
[Submitted on 14 Nov 2021]
Crustal properties of a neutron star within an effective relativistic mean-field model
Vishal Parmar · H. C. Das · Ankit Kumar · M. K. Sharma · S. K. Patra
We use the effective relativistic mean-field (E-RMF) model to study the crustal properties of the neutron star. The unified equations of state (EoS) are constructed using recently developed E-RMF parameter sets, such as FSUGarnet, IOPB-I, and G3. The outer crust composition is determined using the atomic mass evaluation 2020 data [Chinese Physics C {\bf 45}, 030002 (2021)] along with the available Hartree-Fock-Bogoliubov mass models [Phys. Rev. C {\bf 88}, 024308 (2013)] for neutron-rich nuclei. The structure of the inner crust is estimated by performing the compressible liquid drop model calculations using the same E-RMF functional as that for the uniform nuclear matter in the liquid core. Various neutron star properties such as mass-radius ( $M - R$ ) relation, the moment of inertia ( $I$ ), the fractional crustal moment of inertia ( $I_{cr u s t} / I$ ), mass ( $M_{cr u s t})$ and thickness ( $l_{cr u s t}$ ) of the crust are calculated with three unified EoSs. The crustal properties are found to be sensitive to the density-dependent symmetry energy and slope parameter advocating the importance of the unified treatment of neutron star EoS. The three unified EoSs, IOPB-I-U, FSUGarnet-U, and G3-U, reproduced the observational data obtained with different pulsars, NICER, and glitch activity and are found suitable for further description of the structure of the neutron star.
Comments:
19 pages, 14 figures, 7 tables, Published in Phys. Rev. D. The unified equations of states are available in the GitHub link - https://github.com/hcdas/Unified_eos
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2111.07278 [pdf]
PRD(2022)·27 citations
03
[Submitted on 14 Nov 2021]
Model study of the energy dependence of the correlation between anisotropic flow and the mean transverse momentum in Au+Au collisions
Niseem Magdy🇺🇸 · Petr Parfenov🇷🇺 · Arkadiy Taranenko🇷🇺 · Iurii Karpenko🇨🇿 · Roy A. Lacey🇺🇸
A hybrid model that employs the hadron-string transport model UrQMD and the (3+1)D relativistic viscous hydrodynamic code vHLLE, is used to investigate the beam energy dependence of the correlation coefficient $ρ (v_{2}^{2}, [p_{T}])$ between the average transverse momentum $[p_{T}]$ of hadrons emitted in an event and the square of the anisotropic flow coefficient $v_{2}^{2}$ . For Au+Au collisions, the model predicts characteristic patterns for the energy and event-shape dependence of the variances for $[p_{T}]$ and $v_{n}^{2}$ ( $Var ([p_{T}])$ and $Var (v_{2}^{2})$ ), and the covariance of $v_{n}^{2}$ and $[p_{T}]$ ( $cov (v_{2}^{2}, [p_{T}])$ ), consistent with the attenuation effects of the specific shear viscosity $η / s$ . In contrast, $ρ (v_{2}^{2}, [p_{T}])$ is predicted to be insensitive to the beam energy but sensitive to the initial-state geometry of the collisions. These observations suggest that a precise set of measurements for $Var ([p_{T}])$ , $Var (v_{2}^{2})$ , $cov (v_{2}^{2}, [p_{T}])$ and $ρ (v_{2}^{2}, [p_{T}])$ as a function of beam-energy and event-shape, could aid precision extraction of the temperature and baryon chemical-potential dependence of $η / s$ from the wealth of Au+Au data obtained in the RHIC beam energy scan.
Comments:
6 pages, 6 figures, submitted for publication
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2111.07406 [pdf]
PRC(2022)·8 citations
04
[Submitted on 15 Nov 2021]
$α$ knockout reaction as a new probe for $α$ formation in $α$ -decay nuclei
Kazuki Yoshida · Junki Tanaka
The $α$ -decay phenomennon has been studied for more than a century but the mechanism of the $α$ particle formation and its tunneling process have not yet been fully understood. As an alternative to the $α$ -decay lifetime measurement, we propose the proton-induced $α$ knockout reaction, ( $p$ , $p α$ ), as a new probe for the surface $α$ formation probability of $α$ -decay nuclei. The $^{210, 212}$ Po( $p$ , $p α$ ) $^{206, 208}$ Pb reaction is described by the distorted-wave impulse approximation framework. It shows that the $^{212}$ Po/ $^{210}$ Po ratio of the $α$ knockout cross sections agrees with that of the surface $α$ formation probabilities determined by lifetime measurements. The result implies that the ( $p$ , $p α$ ) cross section is a direct probe for the surface $α$ formation probability, which is an essential quantity to lead us to a complete understanding of the $α$ -decay phenomenon.
Comments:
5 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2111.07541 [pdf]
PRC(2022)·14 citations
05
[Submitted on 15 Nov 2021]
Nuclear medium effects in the deep inelastic $ν_{τ} / ν ˉ_{τ} -^{40} A r$ scattering at DUNE energies
F. Zaidi🇮🇳 · V. Ansari🇮🇳 · M. Sajjad Athar🇮🇳 · H. Haider🇮🇳 · I. Ruis Simo🇪🇸 · S. K. Singh🇮🇳
The nuclear medium effects are studied in the $ν_{τ} / ν ˉ_{τ}$ interactions from nuclei in the deep inelastic scattering (DIS) region and applied to the $^{40} A r$ nucleus to obtain the scattering cross sections in the energy region of the proposed DUNE experiment. The free nucleon structure functions ( $F_{i N} (x, Q^{2}); (i = 1 - 5)$ ) have been calculated at the next-to-leading order (NLO) using Martin-Motylinski-Harland Lang-Thorne 2014 as well as The Coordinated Theoretical-Experimental Project on QCD parameterizations for parton distribution functions (PDFs) and including the effect of perturbative and nonperturbative QCD corrections \cite{Ansari:2020xne}. These free nucleon structure functions are then convoluted with the nucleon spectral function in the nucleus to obtain the nuclear structure functions ( $F_{i A} (x, Q^{2}); (i = 1 - 5)$ ). The nucleon spectral function takes into account the Fermi motion and the binding energy of the nucleons as well as the nucleon correlations within the nucleus. These nuclear structure functions are then used to calculate the deep inelastic scattering cross sections. Moreover, the contribution of $π$ and $ρ$ mesons as well as the corrections due to the shadowing and antishadowing effects in the relevant kinematic region of the Bjorken variable $x$ are also included. The numerical results for the cross sections have been presented and compared with the results obtained in the phenomenological approach using nuclear structure functions from nCTEQnu.
Comments:
26 pages and 20 figures and 1 table
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2111.07609 [pdf]
PRD(2022)·9 citations
06
[Submitted on 15 Nov 2021]
Microscopic study of higher-order deformation effects on the ground states of superheavy nuclei around $^{270}$ Hs
Xiao-Qian Wang · Xiang-Xiang Sun · Shan-Gui Zhou
We study the effects of higher-order deformations $β_{λ}$ ( $λ = 4, 6, 8,$ and $10$ ) on the ground state properties of superheavy nuclei (SHN) near the doubly magic deformed nucleus $^{270}$ Hs by using the multidimensionally-constrained (MDC) relativistic mean-field (RMF) model with five effective interactions PC-PK1, PK1, NL3 $^{*}$ , DD-ME2, and PKDD. The doubly magic properties of $^{270}$ Hs are featured by the large energy gaps at $N = 162$ and $Z = 108$ in the single-particle spectra. By investigating the binding energies and single-particle levels of $^{270}$ Hs in multidimensional deformation space, we find that the deformation $β_{6}$ has the greatest impact on the binding energy among these higher-order deformations and influences the shell gaps considerably. Similar conclusions hold for other SHN near $^{270}$ Hs. Our calculations demonstrate that the deformation $β_{6}$ must be considered when studying SHN by using MDC-RMF.
Comments:
accepted for publication in Chin. Phys. C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2111.07612 [pdf]
CPC(2022)·22 citations
07
[Submitted on 15 Nov 2021]
Comparison of heavy ion transport simulations: Ag+Ag collisions at Elab = 1.58 AGeV
Tom Reichert🇩🇪 · Alexander Elz🇩🇪 · Taesoo Song🇩🇪 · Gabriele Coci🇩🇪 · Michael Winn🇫🇷 · Elena Bratkovskaya🇩🇪 · Jörg Aichelin🇫🇷 · Jan Steinheimer🇩🇪 · Marcus Bleicher🇩🇪
We compare the microscopic transport models UrQMD, PHSD, PHQMD, and SMASH to make predictions for the upcoming Ag+Ag data at $E_{lab} = 1.58$ ~ $A$ GeV ( $s_{NN} = 2.55$ ~GeV) by the HADES collaboration. We study multiplicities, spectra and effective source temperatures of protons, $π^{\pm, 0}$ , $K^{\pm}$ , the $η$ , $Λ + Σ^{0}$ and the $Ξ^{-}$ within these models. Despite variations in the detailed implementation of the dynamics in the different models, the employed transport approaches all show consistent multiplicities of the bulk of investigated hadrons. The main differences are in the $Ξ^{-}$ production, which is treated differently between UrQMD/SMASH on one side employing high mass resonance states with explicit decays to $Resonance \to Ξ + K + K$ in contrast to PHSD/PHQMD which account only non-resonant $Ξ$ production channels. A comparison of the spectra, summarized by effective source temperatures, shows that all models provide similar source temperatures around $T_{source} = 80 - 95$ ~MeV, and show substantial radial flow on the order of $⟨ v_{T} ⟩ = 0.22 c - 0.3 c$ even for such a small system.
Comments:
13 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2111.07652 [pdf]
J.Phys.G(2022)·21 citations
08
[Submitted on 15 Nov 2021]
Accurate relativistic chiral nucleon-nucleon interaction up to NNLO
Jun-Xu Lu🇨🇳 · Chun-Xuan Wang🇨🇳 · Yang Xiao🇨🇳 · Li-Sheng Geng🇨🇳 · Jie Meng🇨🇳 · Peter Ring🇩🇪
We construct a relativistic chiral nucleon-nucleon interaction up to the next-to-next-to-leading order in covariant baryon chiral perturbation theory. We show that a good description of the $n p$ phase shifts up to $T_{lab} = 200$ MeV and even higher can be achieved with a $χ ~^{2} / d.o.f.$ less than 1. Both the next-to-leading order results and the next-to-next-to-leading order results describe the phase shifts equally well up to $T_{lab} = 200$ MeV, but for higher energies, the latter behaves better, showing satisfactory convergence. The relativistic chiral potential provides the most essential inputs for relativistic ab initio studies of nuclear structure and reactions, which has been in need for almost two decades.
Comments:
Accepted for publication in PRL. Uncertainty estimates updated and comparison with the Granada PWA added
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2111.07766 [pdf]
PRL(2022)·69 citations
09
[Submitted on 15 Nov 2021]
Three-body renormalization group limit cycles based on unsupervised feature learning
Bastian Kaspschak · Ulf-G. Meißner
Both the three-body system and the inverse square potential carry a special significance in the study of renormalization group limit cycles. In this work, we pursue an exploratory approach and address the question which two-body interactions lead to limit cycles in the three-body system at low energies, without imposing any restrictions upon the scattering length. For this, we train a boosted ensemble of variational autoencoders, that not only provide a severe dimensionality reduction, but also allow to generate further synthetic potentials, which is an important prerequisite in order to efficiently search for limit cycles in low-dimensional latent space. We do so by applying an elitist genetic algorithm to a population of synthetic potentials that minimizes a specially defined limit-cycle-loss. The resulting fittest individuals suggest that the inverse square potential is the only two-body potential that minimizes this limit cycle loss independent of the hyperangle.
Comments:
24 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th); Machine Learning (cs.LG); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Computational Physics (physics.comp-ph)
arXiv:
2111.07820 [pdf]
Mach.Learn.Sci.Tech.(2022)·5 citations
10
[Submitted on 15 Nov 2021]
From neutron skins and neutron matter to the neutron star crust
William G. Newton · Rebecca Preston · Lauren Balliet · Michael Ross
We present the first Bayesian inference of neutron star crust properties to incorporate neutron skin data, including the recent PREX measurement of the neutron skin of $^{208}$ Pb, combined with recent chiral effective field theory predictions of pure neutron matter with statistical errors. Using a compressible liquid drop model with an extended Skyrme energy-density functional, we obtain the most stringent constraints to date on the transition pressure $P_{cc} = 0.3 3_{- 0.07}^{+ 0.07}$ MeV fm $^{- 3}$ and chemical potential $μ_{cc} = 12. 6_{- 1.9}^{+ 1.8}$ MeV (which control the mass, moment of inertia and thickness of a neutron star crust), the proton fractions that bracket the pasta phases $y_{p} = 0.11 5_{- 0.017}^{+ 0.016}$ and $y_{cc} = 0.04 1_{- 0.006}^{+ 0.007}$ , as well as the relative mass and moment of inertia $Δ M_{p} /Δ M_{c} \approx Δ I_{p} /Δ I_{c} = 0.5 4_{- 0.09}^{+ 0.05}$ and thickness $Δ R_{p} /Δ R_{c} = 0.12 9_{- 0.030}^{+ 0.019}$ of the layers of non-spherical nuclei (nuclear pasta) in the crust.
Comments:
7 pages, 6 figures, 1 tables; Accepted for publication in Physics Letters B
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2111.07969 [pdf]
PLB(2022)·21 citations

Affiliations

first authorsco-authorsvia INSPIRE