Nuclear Theory·nucl-th

Thursday·July 28, 2022

13 papers—8 primary·5 cross-listed

01
Quantum microscopic dynamical approaches
Cedric Simenel
Nuclear physics is ideal to test and develop techniques to describe the microscopic dynamics of quantum many-body systems. At low energy, nuclear dynamics is described with non-relativistic approaches based on the mean-field approximation and its extensions. Variational principles based on the stationarity of the action are introduced to build theoretical models with different levels of approximation. In particular, the time-dependent Hartree-Fock (TDHF) equation for mean-field dynamics and its linear approximation, also known as the Random Phase Approximation (RPA), are derived. Predictions of vibrational spectra at the RPA level are presented as an application. The inclusion of beyond TDHF correlations and fluctuations are then discussed. In particular, pairing correlations are treated at the BCS and Bogoliubov levels. The Balian-Veneroni variational principle is finally introduced. In addition to provide some insight into mean-field limitations, it offers a possibility to incorporate quantum fluctuations of one-body observables with the time-dependent RPA formalism.
nucl-th0 citations
02
Impact of tensor force on quantum shell effects in quasifission reactions
Liang Li · Lu Guo · K. Godbey · A. S. Umar
Quantum shell effects drive many aspects of many-body quantal systems and their interactions. Among these are the quasifission reactions that impede the formation of a compound nucleus in superheavy element (SHE) searches. Fragment production in quasifission is influenced by shell effects as a nontrivial manifestation of microscopic dynamics hindering the full equilibration of the composite system to form the compound nucleus. In this Letter, we use the microscopic time-dependent Hartree-Fock (TDHF) theory to study 48Ca+249Bk collisions to investigate the influence of the tensor component of the effective nucleon-nucleon interaction. The results show that the inclusion of the tensor force causes the spherical shell effect to become more prominent, particularly for the neutron number yield whose peak is exactly at magic number N = 126. This suggests that the tensor force plays a compelling role in the evolution of dynamical shell effects in nuclear reactions, influencing the competition between spherical and deformed shell gaps.
nucl-thPLB(2022)·21 citations
03
The study of the alpha formation probability in 10Be and 12Be within the microscopic cluster model
Qing Zhao · Masaaki Kimura · Bo Zhou · Seung-heon Shin
The alpha clustering in the 10Be and 12Be has been studied within the framework of the real-time evolution method (REM). By using the effective interaction tuned to reproduce the charge radii and the threshold energies, we have evaluated the alpha reduced width amplitude (RWA) and spectroscopic factor (S-factor) for the ground and excited states. With several improvements made in this work, comparing with our previous calculations, larger rate of clustering results are obtained for the 10Be and 12Be with correct asymptotic at large distance.
nucl-thPRC(2022)·13 citations
04
Properties of glitching pulsars in the Skyrme-Hartree-Fock framework
Joydev Lahiri · Debasis Atta · D. N. Basu
We address the issues of crustal properties of neutron stars such as crustal mass, crustal radius, crustal fraction of moment of inertia and investigate the crustal and structural properties related to the glitching mechanism observed in pulsars. The mass, radius and crustal fraction of moment of inertia in neutron stars have been determined using $β$ -equilibrated (npe $μ$ ) dense neutron star matter obtained using the extended Skyrme effective interactions with NRAPR and Brussels-Montreal parameter sets. The maximum mass of neutron star calculated from these sets is able to reach $\sim$ 2 $M_{⊙}$ and higher, corroborating the recently observed masses of compact stars. The crustal fraction of the moment of inertia depends sensitively on the pressure and corresponding density at core-crust transition. The core-crust transition density and pressure together with the extracted minimum crustal fraction of the total moment of inertia provide a limit for the radii of pulsars. Present calculations imply that due to crustal entrainment the crustal fraction of the total moment of inertia is about 5.5 $%$ .
nucl-thastro-ph.HEPramana(2024)·3 citations
05
Bayesian Inference of the Specific Shear and Bulk Viscosities of the Quark-Gluon Plasma at Crossover from $ϕ$ and $Ω$ Observables
Zhidong Yang🇨🇳 · Lie-Wen Chen🇨🇳
Due to their weak final state interactions, the $ϕ$ meson and $Ω$ baryon provide unique probes of the properties of the quark-gluon plasma (QGP) formed in relativistic heavy-ion collisions. Using the quark recombination model with the quark phase-space information parameterized in a viscous blastwave, we study the transverse-momentum spectra and elliptic flows of $ϕ$ and $Ω$ in Au+Au collisions at $s_{NN} = 200$ GeV and Pb+Pb collisions at $s_{NN} = 2.76$ TeV. The viscous blastwave includes non-equilibrium deformations of thermal distributions due to shear and bulk stresses and thus carries information on the specific shear viscosity $η / s$ and the specific bulk viscosity $ζ / s$ of the QGP. We perform a model-to-data comparison with Bayesian inference and simultaneously obtain $η / s = (2.0 8_{- 1.09}^{+ 1.10}) /4 π$ and $ζ / s = 0.0 6_{- 0.04}^{+ 0.04}$ at $90%$ C.L. for the baryon-free QGP at crossover temperature of about $160$ MeV. Our work provides a novel approach to simultaneously determine the $η / s$ and $ζ / s$ of the QGP at hadronization.
nucl-thhep-phnucl-exPRC(2023)·16 citations
06
Microscopic study on fusion reactions $^{40, 48} Ca +^{78} Ni$ and the effect of tensor force
Xiang-Xiang Sun · Lu Guo · A. S. Umar
We provide a microscopic description of the fusion reactions between $^{40, 48}$ Ca and $^{78}$ Ni. The internuclear potentials are obtained using the density-constrained (DC) time-dependent Hartree-Fock (TDHF) approach and fusion cross sections are calculated via the incoming wave boundary condition method. By performing DC-TDHF calculations at several selected incident energies, the internuclear potentials for both systems are obtained and the energy-dependence of fusion barrier are revealed. The influence of tensor force on internuclear potentials of $^{48} Ca +^{78} Ni$ is more obvious than those of $^{40} Ca +^{78} Ni$ . By comparing the calculated fusion cross sections between $^{40} Ca +^{78} Ni$ and $^{48} Ca +^{78} Ni$ , an interesting enhancement of sub-barrier fusion cross sections for the former system is found, which can be explained by the narrow width of internuclear potential for $^{40} Ca +^{78} Ni$ while the barrier heights and positions are very close to each other. The tensor force suppresses the sub-barrier fusion cross sections of both two systems.
nucl-thPRC(2022)·19 citations
07
Structure of $^{128, 129, 130}$ Xe through multi-reference energy density functional calculations
Benjamin Bally🇫🇷 · Giuliano Giacalone🇩🇪 · Michael Bender🇫🇷
Recently, values for the Kumar quadrupole deformation parameters of the nucleus $^{130}$ Xe have been computed from the results of a Coulomb excitation experiment, indicating that this xenon isotope has a prominent triaxial ground state. Within a different context, it was recently argued that the analysis of particle correlations in the final states of ultra-relativistic heavy-ion collisions performed at the Large Hadron Collider (LHC) points to a similar structure for the adjacent isotope, $^{129}$ Xe. In the present work, we report on state-of-the-art multi-reference energy density functional calculations that combine projection on proton and neutron number as well as angular momentum with shape mixing for the three isotopes $^{128, 129, 130}$ Xe using the Skyrme-type pseudo-potential SLyMR1. Exploring the triaxial degree of freedom, we demonstrate that the ground states of all three isotopes display a very pronounced triaxial structure. Moreover, comparison with experimental results shows that the calculations reproduce fairly well the low-energy excitation spectrum of the two even-mass isotopes. By contrast, the calculation of $^{129}$ Xe reveals some deficiencies of the effective interaction.
nucl-thEPJA(2022)·23 citations
08
Production of proton-rich nuclei in the vicinity of 100Sn via multinucleon transfer reactions
Zhenji Wu · Lu Guo · Zhong Liu · Guangxiong Peng
The production of new proton-rich nuclei in the vicinity of 100Sn is investigated via multinucleon transfer reactions within the framework of microscopic time-dependent Hartree-Fock (TDHF) and statistical model GEMINI++. The TDHF+GEMINI method has demonstrated the reliable description in the multinucleon transfer dynamics and the agreement between theoretical results and experimental data is quite satisfactory in the observed transfer reactions. We reveal the production cross sections of proton-rich nuclei in 100Sn region via multinucleon transfer reactions to be several orders of magnitude higher than those measured via fusion-evaporation and projectile fragmentation experiments. About 19 new proton-rich isotopes with cross sections of larger than 1 nb are predicted to be produced in multinucleon transfer reaction of 58Ni with 112Sn. The reaction mechanisms are discussed to lead the experimental production of these previously unreported nuclei. Multinucleon transfer reactions provide a fascinating possibility to reach the proton drip-line in 100Sn region and beyond.
nucl-thPLB(2022)·42 citations

Affiliations

first authorsco-authorsvia INSPIRE