Nuclear Theory·nucl-th

Thursday·February 16, 2023

17 papers—10 primary·7 cross-listed

01
[Submitted on 14 Feb 2023]
Second-Order Perturbation Theory in Continuum Quantum Monte Carlo Calculations
Ryan Curry · Joel E. Lynn · Kevin E. Schmidt · Alexandros Gezerlis
We report on the first results for the second-order perturbation theory correction to the ground-state energy of a nuclear many-body system in a continuum quantum Monte Carlo calculation. Second-order (and higher) perturbative corrections are notoriously difficult to compute in most ab initio many-body methods, where the focus is usually on obtaining the ground-state energy. By mapping our calculation of the second-order energy correction to an evolution in imaginary time using the diffusion Monte Carlo method, we are able to calculate these nuclear corrections for the first time. After benchmarking our method in the few-body sector, we explore the effect of charge-independence-breaking terms in the nuclear Hamiltonian. We then employ that approach to investigate the many-body, perturbative, order-by-order convergence that is fundamental in modern theories of the nucleon-nucleon interaction derived from chiral effective field theory. We find cutoff-dependent perturbativeness between potentials at higher chiral order and also that the difference between leading order and next-to-leading order potentials is nonperturbative; both of these results have important implications for future nuclear many-body calculations. Our approach is quite general and promises to be of wide applicability.
Comments:
6 pages, 3 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); Quantum Gases (cond-mat.quant-gas); Computational Physics (physics.comp-ph)
arXiv:
2302.07285 [pdf]
PRResearch(2023)·15 citations
02
[Submitted on 14 Feb 2023]
Differential charge radii: self-consistency and proton-neutron interaction effects
U. C. Perera · A. V. Afanasjev
The analysis of self-consistency and proton-neutron interaction effects in the buildup of differential charge radii has been carried out in covariant density functional theoretical calculations without pairing interaction. Two configurations of the $^{218}$ Pb nucleus, generated by the occupation of the neutron $1 i_{11/2}$ and $2 g_{9/2}$ subshells, are compared with the ground state configuration in $^{208}$ Pb. The interaction of added neutron(s) and the protons forming the $Z = 82$ proton core is responsible for a major contribution to the buildup of differential charge radii. It depends on the overlaps of proton and neutron wave functions and leads to a redistribution of single-particle density of occupied proton states which in turn modifies the charge radii. Self-consistency effects affecting the shape of proton potential, total proton densities and the energies of the single-particle proton states provide only secondary contribution to differential charge radii. The buildup of differential charge radii is a combination of single-particle and collective phenomena. The former is due to proton-neutron interaction, the impact of which is state dependent, and the latter reflects the fact that all occupied proton single-particle states contribute to this process. The neglect of either one of these aspects of the process by ignoring proton-neutron interaction and self-consistency effects as it is done in macroscopic+microscopic approach or by introducing the core as in spherical shell model introduces uncontrollable errors and restricts the applicability of such approaches to the description of differential charge radii.
Comments:
14 pages, 8 figures, submitted to Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2302.07295 [pdf]
PRC(2023)·13 citations
03
[Submitted on 15 Feb 2023]
Shape and multiple shape coexistence of nuclei within covariant density functional theory
Y. L. Yang · P. W. Zhao · Z. P. Li
Shape and multiple shape coexistence of nuclei are investigated throughout the nuclear chart by calculating the low-lying spectra and the quadrupole shape invariants for even-even nuclei with $10 \leq Z \leq 104$ from the proton drip line to the neutron one within a five-dimensional collective Hamiltonian based on the covariant density functional PC-PK1. The quadrupole shape invariants are implemented to characterize the quadrupole deformations of low-lying $0^{+}$ states and predict nuclear mass regions of shape and multiple shape coexistence. The predicted low-lying spectra and the shape or multi-shape coexisting nuclei are overall in good agreement with the available experimental results. In addition, the present work predicts a wealth of nuclei with shape or multiple shape coexistence in the neutron-rich regions. The connection between the strong $E 0$ transition strength and the occurrence of shape coexistence is analyzed systemically. It is found that nuclei with pronounced shape coexistence generally have strong $E 0$ transition strengths, while the reverse may not be true. The present results can serve as useful guidelines for experimental searches and theoretical studies of shape and multiple shape coexistence, especially in neutron-rich regions.
Comments:
8 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2302.07417 [pdf]
PRC(2023)·24 citations
04
[Submitted on 15 Feb 2023]
Systematic shell-model study of $^{98 - 130}$ Cd isotopes and $8^{+}$ isomeric states
Deepak Patel · Praveen C. Srivastava · Noritaka Shimizu
We present systematic shell-model studies of even-even $^{98 - 130}$ Cd isotopes using a realistic effective shell-model interaction derived from the G-matrix approach with an inert core $^{88}$ Sr. Our calculated low-lying excited energy spectra and electromagnetic properties are compared with the experimental data. On the basis of recently available experimental data, we predict spins and parities corresponding to unconfirmed states. We also discuss the properties of $8^{+}$ isomeric states in $^{98 - 104, 130}$ Cd isotopes.
Comments:
20 pages, 13 figures,
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2302.07514 [pdf]
NPA(2023)·4 citations
05
[Submitted on 15 Feb 2023]
Preequilibrium cluster emission in massive transfer reactions near Coulomb barrier energy
Zhao-Qing Feng
Within the framework of the dinuclear system model, the preequilibrium emission of neutron, proton, deuteron, triton, $^{3}$ He, $α$ , $^{6}$ Li, $^{7}$ Li, $^{8}$ Be and $^{9}$ Be in the transfer reactions of $^{12}$ C + $^{209}$ Bi, $^{40, 48}$ Ca+ $^{238}$ U, $^{238}$ U+ $^{238}$ U and $^{238}$ U+ $^{248}$ Cm has been systematically investigated. The production rate, kinetic energy spectra and emission angular distribution are calculated. It is found that the preequilibrium emission mechanism is associated with the reaction system and beam energy. The preequilibrium cross sections of proton, deuteron, triton and alpha are comparable in magnitude. The reaction with $^{40}$ Ca is favorable for the cluster emission in comparison with $^{48}$ Ca on $^{238}$ U at the near barrier energy. A broad angular distribution of the preequilibrium cluster is found in the heavy systems $^{238}$ U+ $^{238}$ U and $^{238}$ U+ $^{248}$ Cm.
Comments:
9 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2302.07544 [pdf]
PRC(2023)·2 citations
06
[Submitted on 15 Feb 2023]
Production of Strange and Charm Hadrons in Pb+Pb Collisions at $s_{N N} =$ 5.02 TeV
Wen-bin Chang🇨🇳 · Rui-qin Wang🇨🇳 · Jun Song🇨🇳 · Feng-lan Shao🇨🇳 · Qun Wang🇨🇳 · Zuo-tang Liang🇨🇳
Using a quark combination model with the equal-velocity combination approximation, we study the production of hadrons with strangeness and charm flavor quantum numbers in Pb+Pb collisions at $s_{N N} =$ 5.02 TeV. We present analytical expressions and numerical results for these hadrons' transverse momentum spectra and yield ratios. Our numerical results agree well with the experimental data available. The features of strange and charm hadron production in the quark--gluon plasma at the early stage of heavy ion collisions are also discussed.
Comments:
12 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2302.07546 [pdf]
Symmetry(2023)·3 citations
07
[Submitted on 15 Feb 2023]
Hidden Euclidean dynamical symmetry in the U(n+1) vibron model
Yu Zhang · Zi-Tong Wang · Hong-Di Jiang · Xin Chen
Based on the boson realization of the Euclidean algebras, it is found that the E( $n$ ) dynamical symmetry (DS) may emerge at the critical point of the U( $n$ )-SO( $n + 1$ ) quantum phase transition. To justify this finding, we provide a detailed analysis of the critical dynamics in the U( $n + 1$ ) vibron model in both quantal and classical ways. It is further shown that the low-lying structure of $^{82}$ Kr may serve as an excellent empirical realization of the E(5) DS in experiments.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2302.07602 [pdf]
Symmetry(2022)·5 citations
08
[Submitted on 15 Feb 2023]
Quadrupole and octupole states in $^{152}$ Sm using the proton-neutron interacting boson model
Bao-Yue Hu · Yu Zhang · Gui-Xiu Na · Sheng-Nan Wang · Wei Teng
A scheme of solving the proton-neutron interacting boson model (IBM-2) in terms of the SU(3) basis is introduced, by which the IBM-2 coupled with an octupole boson is applied to describe the low-energy structure of the critical point nucleus, $^{152}$ Sm. The results indicate that the spectral properties of both the positive-parity bands and negative-parity bands in this nucleus can be well captured by the IBM-2 calculations through a simple Hamiltonian, thus providing an example of the IBM-2 in a unified description of quadrupole and octupole states in a transitional system. In addition, a statistical analysis of the low-spin states in the model is also provided.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2302.07610 [pdf]
J.Phys.G(2023)·2 citations
09
[Submitted on 15 Feb 2023]
The effect of weak magnetic photon emission from quark-gluon plasma
Jing-An Sun🇨🇳 · Li Yan🇨🇳
We propose a novel effect that accounts for the photon emission from a quark-gluon plasma in the presence of a weak external magnetic field. Although the weak magnetic photon emission from quark-gluon plasma only leads to a small correction to the photon production rate, the induced photon spectrum can be highly azimuthally anisotropic, as a consequence of the coupled effect of the magnetic field and the longitudinal dynamics in the background medium. With respect to a realistic medium evolution containing a tilted fireball configuration, the direct photon elliptic flow from experiments is reproduced. In comparison to the experimental data of direct photon elliptic flow, in heavy-ion collisions the magnitude of the magnetic field before 1 fm/c can be extracted. For the top energy of RHIC collisions, right after the pre-equilibrium evolution, $∣ e B ∣$ is found no larger than a few percent of the pion mass square.
Comments:
revised version with a new appendix in the supplemental material. code used to calculate photon yields and elliptic flow uploaded
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2302.07696 [pdf]
PLB(2024)·16 citations
10
[Submitted on 13 Feb 2023]
Generation, dynamics, and correlations of the fission fragments' angular momenta
Guillaume Scamps · George Bertsch
The generation of angular momentum in fissioning nuclei is not well understood. The predictions of different models disagree, particularly concerning the correlation between the fragments' angular momenta. In this article, a time-dependent collective Hamiltonian model is proposed to treat the generation of the angular momentum in the fission fragments due to the quantum uncertainty principle as well as the dynamics of the collective wave function during and after scission. The model is constructed in the framework of the frozen Hartree-Fock approximation using a Skyrme energy functional to extract deformations of the fission fragments as well as the interactions in a derived collective Hamiltonian. The fission reactions studied are $^{240}$ Pu $\to$ $^{132}$ Sn+ $^{108}$ Ru and $^{240}$ Pu $\to$ $^{144}$ Ba+ $^{96}$ Sr. The model can account for a large part of the angular momentum found in experimental data. The orientation of the angular momentum of each fragment is found to be mainly in the plane perpendicular to the fission axis, in agreement with the experiment. The magnitudes of the angular momenta in the two fragments are nearly uncorrelated, in agreement with the recent experimental data of Wilson et al., Nature (London) 590, 566 (2021). Some of the conclusions of the traditional collective vibration model are supported by the present model but some are not. Surprisingly, it is found that the angular momenta of the fragments are slightly correlated positively as in a wriggling mode. It is also found that the presence of an octupole deformation in a fragment can significantly increase the generated angular momentum.
Comments:
14 pages, 15 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2302.07792 [pdf]
PRC(2023)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE