Nuclear Theory·nucl-th

Thursday·March 10, 2022

12 papers—8 primary·4 cross-listed

01
[Submitted on 9 Mar 2022]
Model for independent particle motion
A.V. Afanasjev
Independent particle model in nuclear physics assumes that the nucleon in the nucleus moves in the average (mean field) potential generated by all other nucleons. This chapter gives a short overview of basic features of the independent particle motion in atomic nuclei and its theoretical realization in the framework of shell models for spherical, deformed and rotating nuclei as well as in more sophisticated approaches such as microscopic+macroscopic model and density functional theories. Independent particle motion of nucleons leads to global and single-particle consequences. The global ones manifest themselves in the shell structure and its consequences for global structure of nuclear landscape, the existence of superheavy nuclei and the superdeformation at high spin are briefly reviewed. The latter shows itself in the single-particle properties such as energies, alignments and densities; their manifestations are illustrated on specific examples.
Comments:
38 pages, 14 figures, Contribution to the "Handbook of Nuclear Physics", Springer Nature, 2022, Eds. I. Tanihata, H. Toki and T. Kajino, revised version
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2203.04460 [pdf]
in "Handbook of Nuclear Physics", edited …·0 citations
02
[Submitted on 9 Mar 2022]
The impact of isospin dependence of pairing on fission barriers in the fission cycling regions
A.V. Afanasjev · A. Taninah
A systematic analysis of the ground state and fission properties of actinides and superheavy nuclei important for the $r$ process modeling has been performed within the framework of covariant density functional theory for the first time in Ref. [1]. A brief review of the results related to the heights of primary fission barriers and systematic uncertainties in their prediction is presented. In addition, new results on the potential impact of the isospin dependence of pairing on fission barriers in fission cycling regions is provided for the first time.
Comments:
4 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2203.04480 [pdf]
EPJ Web Conf.(2022)·0 citations
03
[Submitted on 9 Mar 2022]
Quenched {\Lambda} spin-orbit splitting by relativistic Fock diagram in single-{\Lambda} hypernuclei
Shi Yuan Ding🇨🇳 · Zhuang Qian🇨🇳 · Bao Yuan Sun🇨🇳 · Wen Hui Long🇨🇳
We extend the relativistic Hartree-Fock (RHF) theory to study the structure of single- $Λ$ hypernuclei. The density dependence is taken in both meson-nucleon and meson-hyperon coupling strengths, and the induced $Λ$ -nucleon ( $Λ N$ ) effective interactions are determined by fitting $Λ$ separation energies to the experimental data for several single- $Λ$ hypernuclei. The equilibrium of nuclear dynamics described by the RHF model in normal atomic nuclei, namely, the balance between nuclear attractive and repulsive interactions, is then found to be drastically changed in single- $Λ$ hypernuclei, revealing a different role of Fock terms via $Λ$ hyperon from the nucleon exchange. Since only one hyperon exists in a single- $Λ$ hypernucleus, the overwhelmed $Λ N$ and $ΛΛ$ attractions via the Hartree than the $ΛΛ$ repulsion from the Fock terms require an alternation of meson-hyperon coupling strengths in RHF to rebalance the effective nuclear force with the strangeness degree of freedom, leading to an improved description of $Λ$ Dirac mass and correspondingly a systematically reduced $σ$ - $Λ$ coupling strength $g_{σ Λ}$ in current models as compared to those relativistic mean-field (RMF) approaches without Fock terms. As a result, the effective $Λ$ spin-orbit coupling potential in the ground state of hypernuclei is suppressed, and these RHF models predict correspondingly a quenching effect in $Λ$ spin-orbit splitting in comparison with the RMF cases. Furthermore, the $Λ$ spin-orbit splitting could decrease efficiently by evolving the hyperon-relevant couplings $g_{σ Λ}$ and $g_{ω Λ}$ simultaneously, where to reconcile with the empirical value the RHF models address a larger parameter space of meson-hyperon couplings.
Comments:
19 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2203.04581 [pdf]
PRC(2022)·15 citations
04
[Submitted on 9 Mar 2022]
Signatures of shape phase transitions in krypton isotopes based on relativistic energy density functionals
K.E. Karakatsanis · K. Nomura
Spectroscopic properties that characterize the shape phase transitions in krypton isotopes with the mass $A \approx 80$ region are investigated within the framework of the nuclear density functional theory. Triaxial quadrupole constrained self-consistent mean-field calculations that employ relativistic energy density functionals and a pairing interaction are carried out for the even-even nuclei $^{76 - 86}$ Kr. The spectroscopic properties are computed by solving the triaxial quadrupole collective Hamiltonian, with the ingredients, i.e., the deformation-dependent moments of inertia and mass parameters, and the collective potential, determined by using the SCMF solutions as microscopic inputs. Systematic behaviors of the SCMF potential energy surfaces, the corresponding low-energy spectra, electric quadrupole and monopole transition probabilities, and the fluctuations in the triaxial quadrupole deformations indicate evolution of the underlying nuclear structure as functions of the neutron number, that is characterized by a considerable degree of shape mixing. A special attention is paid to the transitional nucleus $^{82}$ Kr, which has been recently identified experimentally as an empirical realization of the E(5) critical-point symmetry.
Comments:
15 pages, 10 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2203.04683 [pdf]
PRC(2022)·7 citations
05
[Submitted on 9 Mar 2022]
Longitudinal dynamics and particle production in relativistic nuclear collisions
Chun Shen🇺🇸 · Björn Schenke🇺🇸
This work presents a three-dimensional dynamical initialization model for relativistic heavy-ion collisions, implementing local energy-momentum conservation and baryon charge fluctuations at string junctions. Constraining parameters using experimental data from p+p collisions at various collision energies, the model provides a very good description of the charged hadron and net proton rapidity distributions in Au+Au collisions from 7.7 to 200 GeV and Pb+Pb collisions at 8.77 and 17.3 GeV. We demonstrate the importance of fluctuations of baryon densities to string junctions for describing net-proton distributions at collision energies of 62.4 and 200 GeV. Including this improved baryon stopping description along with the requirement of strangeness neutrality also yields a good description of identified particle yields as functions of the collision energy above 7.7 GeV. We further study asymmetric p+Al and (p, d, $^{3}$ He)+Au collisions at the top RHIC energy and p+Pb, Xe+Xe, and Pb+Pb collisions at LHC energies. We identify the produced particle rapidity distributions in asymmetric collision systems as particularly useful for constraining models of the early-time longitudinal dynamics.
Comments:
20 pages, 19 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2203.04685 [pdf]
PRC(2022)·80 citations
06
[Submitted on 9 Mar 2022]
Relativistic second-order dissipative spin hydrodynamics from the method of moments
Nora Weickgenannt🇩🇪 · David Wagner🇩🇪 · Enrico Speranza🇺🇸 · Dirk Rischke🇩🇪
We derive relativistic second-order dissipative fluid-dynamical equations of motion for massive spin-1/2 particles from kinetic theory using the method of moments. Besides the usual conservation laws for charge, energy, and momentum, such a theory of relativistic dissipative spin hydrodynamics features an equation of motion for the rank-3 spin tensor, which follows from the conservation of total angular momentum. Extending the conventional method of moments for spin-0 particles, we expand the spin-dependent distribution function near local equilibrium in terms of moments of the momentum and spin variables. We work to next-to-leading order in the Planck constant $ℏ$ . As shown in previous work, at this order in $ℏ$ the Boltzmann equation for spin-1/2 particles features a nonlocal collision term. From the Boltzmann equation, we then obtain an infinite set of equations of motion for the irreducible moments of the deviation of the single-particle distribution function from local equilibrium. In order to close this system of moment equations, a truncation procedure is needed. We employ the "14+24-moment approximation", where "14" corresponds to the components of the charge current and the energy-momentum tensor and "24" to the components of the spin tensor, which completes the derivation of the equations of motion of second-order dissipative spin hydrodynamics. For applications to heavy-ion phenomenology, we also determine dissipative corrections to the Pauli-Lubanski vector.
Comments:
30 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
arXiv:
2203.04766 [pdf]
PRD(2022)·129 citations
07
[Submitted on 9 Mar 2022]
Interacting $u d$ and $u d s$ quark matter at finite densities and quark stars
Wen-Li Yuan🇨🇳 · Ang Li🇨🇳 · Zhiqiang Miao🇨🇳 · Bingjun Zuo🇨🇳 · Zhan Bai🇨🇳
The stability and equation of state of quark matter are studied within both two-flavor and (2+1)-flavor Nambu-Jona-Lasinio (NJL) models including the vector interactions. With a free parameter $α$ , the Lagrangian is constructed by two parts, the original NJL Lagrangian and the Fierz transformation of it, as $L = (1 - α) L_{NJL} + α L_{Fierz}$ . We find that there is a possibility for both $u d$ nonstrange and $u d s$ strange matter being absolute stable, depending on the interplay of the confinement with quark vector interaction and the exchange interaction channels. The calculated quark star properties can reconcile with the recently measured masses and radii of PSR J0030+0451 and PSR J0740+6620, as well as the tidal deformability of GW170817. Furthermore, the more strongly-interacting quark matter in the nonstrange stars allows a stiffer equation of state and consequently a higher maximum mass ( $\sim 2.7 M_{⊙}$ ) than the strange ones ( $\sim 2.1 M_{⊙}$ ). The sound velocities in strange and nonstrange quark star matter are briefly discussed compared to those of neutron star matter.
Comments:
13 pages, 9 figures, 2 tables, Phys. Rev. D (2022) accepted
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
2203.04798 [pdf]
PRD(2022)·47 citations
08
[Submitted on 9 Mar 2022]
Measures of complexity and entanglement in fermionic many-body systems
Aurel Bulgac · Matthew Kafker · Ibrahim Abdurrahman
There is no unique and widely accepted definition of the complexity measure (CM) of a many-fermion wave function in the presence of interactions. The simplest many-fermion wave function is a Slater determinant. In shell-model or configuration interaction (CI) and other related methods, the state is represented as a superposition of a large number of Slater determinants, which in case of CI calculations reaches about 20 billion terms. Although in practice this number has been used as a CM for decades, it is ill defined: it is not unique, and it depends on the particular type and the number of single-particle wave functions used to construct the Slater determinants. The canonical wave functions/natural orbitals and their corresponding occupation probabilities are intrinsic properties of any many-body wave function, irrespective of the representation, and they provide a unique solution to characterize the CM. The non-negative orbital entanglement entropy, which vanishes for a Slater determinant, provides the simplest CM, while a more complete measure of complexity is the entanglement spectrum. We illustrate these aspects in the case of a complex non-equilibrium time-dependent process, induced nuclear fission described within a real-time Density Functional Theory framework extended to superfluid systems, which can describe simultaneously the long-range and the short range correlations between fermions.
Comments:
21 pages, 14 figures, published version
Subjects:
Nuclear Theory (nucl-th); Superconductivity (cond-mat.supr-con)
arXiv:
2203.04843 [pdf]
PRC(2023)·46 citations

Affiliations

first authorsco-authorsvia INSPIRE