Nuclear Theory·nucl-th

Friday·July 28, 2023

17 papers—8 primary·9 cross-listed

01
[Submitted on 26 Jul 2023]
Spatial orientation of the fission fragment intrinsic spins and their correlations
Guillaume Scamps · Ibrahim Abdurrahman · Matthew Kafker · Aurel Bulgac · Ionel Stetcu
New experimental and theoretical results obtained in 2021 made it acutely clear that more than 80 years after the discovery of nuclear fission we do not understand the generation and dynamics of fission fragment (FF) intrinsic spins well, in particular their magnitudes, their spatial orientation, and their correlations. The magnitude and orientation of the primary FFs have a crucial role in defining the angular distribution and correlation between the emitted prompt neutrons, and subsequent emission of statistical (predominantly E1) and stretched E2 {\gamma}-rays, and their correlations with the final fission fragments. Here we present detailed microscopic evaluations of the FF intrinsic spins, for both even- and odd-mass FFs, and of their spatial correlations. These point to a well-defined 3D FF intrinsic spin dynamics, characteristics absent in semi-phenomenological studies, due to the presence of the twisting spin modes, which artificially were suppressed in semi-phenomenological studies.
Comments:
4 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2307.14455 [pdf]
PRC(2023)·25 citations
02
[Submitted on 27 Jul 2023]
Short-range correlations and momentum distributions in mirror nuclei 3H and 3He
Qi Meng · Ziyang Lu · Chang Xu
Motivated by recent high-energy electron and $^{3} H$ and $^{3} He$ nuclei scattering experiment in Jefferson Lab (Nature 609, 41 (2022)), the short-range correlations (SRCs) between nucleon pairs for 3-nucleon systems are microscopically studied using realistic $N N$ 2-body interaction and two-Gaussian type $N N N$ 3-body interaction. The wave functions of both $^{3} H$ and $^{3} He$ are obtained by solving 3-body Schrödinger equations using Gaussian expansion method (GEM). The differences of one-nucleon and nucleon-nucleon momentum distributions between $^{3} H$ and $^{3} He$ are analyzed in detail. The results show that the percentages of $p n$ -SRC pairs are significantly enhanced as compared with those of $nn (pp)$ -SRC ones in $^{3} H$ and $^{3} He$ nuclei, which is consistent with the experimental findings.
Comments:
6 pages, 5 figures, to appear in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2307.14592 [pdf]
PRC(2023)·8 citations
03
[Submitted on 27 Jul 2023]
Three-Dimensional Approach Applied to Quasi-stationary States of Deformed $α$ -Emitters
Ruijia Li · Chang Xu
We apply a three-dimensional (3D) approach to investigate the quasi-stationary states of well-deformed $α$ -emitters. With a splitting of the anisotropic 3D potential into internal and external parts at a separation surface, the 3D $α$ -cluster decay width is determined by the initial wave function of a true bound state of an anisotropic harmonic oscillator potential and a non-resonance scattering wave function of Coulomb potential. Substantial difference between the 1D and 3D decay width is found for typical $α$ -emitters with large quadrupole and hexadecapole deformations.
Comments:
16 pages, 5 figures, Phys. Rev. C 107, 064301 (2023)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2307.14598 [pdf]
PRC(2023)·3 citations
04
[Submitted on 27 Jul 2023]
Effects of Critical Point on Quark Gluon Plasma
Md Hasanujjaman🇮🇳
We have used the relativistic second-order causal viscous hydrodynamics equipped with an equation of state which includes the QCD critical point to study the propagation of linear and nonlinear perturbations in quark gluon plasma created in a relativistic heavy-ion collision. We have also studied the behaviour of dynamic structure factor, which is calculated by taking the correlation of dynamical density fluctuation. It is found that the critical point has significant effects on the propagation of linear as well as on nonlinear perturbations. It is also found that the dynamic structure factors are substantially modified with the presence of the QCD critical point.
Comments:
Doctoral thesis
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2307.14601 [pdf]
0 citations
05
[Submitted on 27 Jul 2023]
Elliptic and triangular flow of charmonium states in heavy ion collisions
Sungtae Cho🇰🇷
We study the elliptic and triangular flow of charmonium states, or $J / ψ$ , $ψ (2 S)$ , and $χ_{c} (1 P)$ mesons in heavy ion collisions. Starting from the evaluation of charmonia transverse momentum distributions and yields, we calculate elliptic and triangular flow of charmonium states based on the coalescence model. We show that the internal structure, or the wave function distribution of charmonium states plays a significant role, especially when charmonium states are produced by charm quark recombination, leading to the transverse momentum distribution of the $ψ (2 S)$ meson as half large as that of the $J / ψ$ meson. We also consider the dependence of the elliptic and triangular flow of charmonium states on internal structures of charmonium states, and find that the wave function effects as well as feed-down contributions are averaged out for elliptic and triangular flow, resulting in similar elliptic and triangular flow for all charmonium states. We investigate further the elliptic and triangular flow of charmonium states at low transverse momentum region, and also discuss the quark number scaling of elliptic and triangular flow for charmonium states.
Comments:
20 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2307.14765 [pdf]
PRC(2024)·4 citations
06
[Submitted on 27 Jul 2023]
Reexamining charm versus bottom quark energy loss inside a color-deconfined medium
Yichao Dang🇨🇳 · Wen-Jing Xing🇨🇳 · Shanshan Cao🇨🇳 · Guang-You Qin🇨🇳
The general intuition that heavier partons suffer weaker energy loss inside a quark-gluon plasma (QGP) medium is critically re-examined. Within a linear Boltzmann transport model that includes both Yukawa and string types of interactions between heavy quarks and the QGP, we find that while the radiative energy loss is suppressed by the parton mass, heavier partons can experience stronger string potential scatterings with the medium. Their competition may result in less energy loss of bottom quarks than charm quarks at low transverse momentum ( $p_{T}$ ) but an inverse order at high $p_{T}$ . Our model calculation shows a weaker nuclear modification on bottom particles than charm particles at low $p_{T}$ , as observed by both RHIC and LHC experiments, but predicts an opposite hierarchy at high $p_{T}$ . A larger momentum space transport coefficient ( $q^$ ) and a smaller spatial diffusion coefficient ( $D_{s}$ ) are found for bottom quarks than for charm quarks.
Comments:
9 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2307.14808 [pdf]
PRC(2024)·9 citations
07
[Submitted on 27 Jul 2023]
Triaxial projected shell model approach for negative parity states in even-even nuclei
Nazira Nazir · S. Jehangir · S.P. Rouoof · G.H. Bhat · J.A. Sheikh · N. Rather · Manzoor A. Malik
The triaxial projected shell model (TPSM) approach is generalized to investigate the negative parity band structures in even-even systems. In the earlier version of the TPSM approach, the quasiparticle excitations were restricted to one major oscillator shell and it was possible to study only positive parity states in even-even systems. In the present extension, the excited quasiparticles are allowed to occupy two major oscillator shells, which makes it possible to generate the negative parity states. As a major application of this development, the extended approach is applied to elucidate the negative parity high-spin band structures in $^{102 - 112}$ Ru and it is shown that energies obtained with neutron excitation are slightly lower than the energies calculated with proton excitation. However, the calculated aligned angular momentum ( $i_{x}$ ) clearly separates the two spectra with neutron $i_{x}$ in reasonable agreement with the empirically evaluated $i_{x}$ from the experimental data, whereas proton $i_{x}$ shows large deviations. Furthermore, we have also deduced the transition quadrupole moments from the TPSM wavefunctions along the negative-parity yrast- and yrare- bands and it is shown that these quantities exhibit rapid changes in the bandcrossing region.
Comments:
14 pages, 17 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2307.14827 [pdf]
PRC(2023)·9 citations
08
[Submitted on 25 Jul 2023]
Event Shape Selection Method in Search of the Chiral Magnetic Effect in Heavy-ion Collisions
Zhiwan Xu🇺🇸 · Brian Chan🇺🇸 · Gang Wang🇺🇸 · Aihong Tang🇺🇸 · Huan Zhong Huang🇺🇸
The search for the chiral magnetic effect (CME) in heavy-ion collisions has been impeded by the significant background arising from the anisotropic particle emission pattern, particularly elliptic flow. To alleviate this background, the event shape selection (ESS) technique categorizes collision events according to their shapes and projects the CME observables to a class of events with minimal flow. In this study, we explore two event shape variables to classify events and two elliptic flow variables to regulate the background. Each type of variable can be calculated from either single particles or particle pairs, resulting in four combinations of event shape and elliptic flow variables. By employing a toy model and the realistic event generator, event-by-event anomalous-viscous fluid dynamics (EBE-AVFD), we discover that the elliptic flow of resonances exhibits correlations with both the background and the potential CME signal, making the resonance flow unsuitable for background control. Through the EBE-AVFD simulations of Au+Au collisions at $s_{N N} = 200$ GeV with various input scenarios, we ascertain that the optimal ESS strategy for background control entails utilizing the single-particle elliptic flow in conjunction with the event shape variable based on particle pairs.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex); Instrumentation and Detectors (physics.ins-det)
arXiv:
2307.14997 [pdf]
PLB(2024)·21 citations

Affiliations

first authorsco-authorsvia INSPIRE