Nuclear Theory·nucl-th

Thursday·March 10, 2022

12 papers—8 primary·4 cross-listed

01
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.
nucl-thin "Handbook of Nuclear Physics", edited …·0 citations
02
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.
nucl-thEPJ Web Conf.(2022)·0 citations
03
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.
nucl-thPRC(2022)·15 citations
04
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.
nucl-thnucl-exPRC(2022)·7 citations
05
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.
nucl-thhep-phnucl-exPRC(2022)·80 citations
06
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.
nucl-thhep-phhep-thPRD(2022)·129 citations
07
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.
nucl-thastro-ph.HEastro-ph.SRPRD(2022)·47 citations
08
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.
nucl-thcond-mat.supr-conPRC(2023)·46 citations
09
Merger and post-merger of binary neutron stars with a quark-hadron crossover equation of state
Yong-Jia Huang🇨🇳 · Luca Baiotti🇯🇵 · Toru Kojo🇨🇳 · Kentaro Takami🇯🇵 · Hajime Sotani🇯🇵 · Hajime Togashi🇯🇵 · Tetsuo Hatsuda🇯🇵 · Shigehiro Nagataki🇯🇵 · Yi-Zhong Fan🇨🇳
Fully general-relativistic binary-neutron-star (BNS) merger simulations with quark-hadron crossover (QHC) equations of state (EOSs) are studied for the first time. In contrast to EOSs with purely hadronic matter or with a first-order quark-hadron phase transition (1PT), in the transition region QHC EOSs show a peak in sound speed, and thus a stiffening. We study the effects of such stiffening in the merger and post-merger gravitational (GW) signals. Through simulations in the binary-mass range $2.5 < M / M_{⊙} < 2.75$ , characteristic differences due to different EOSs appear in the frequency of the main peak of the post-merger GW spectrum ( $f_{2}$ ), extracted through Bayesian inference. In particular, we found that (i) for lower-mass binaries, since the maximum baryon number density ( $n_{max}$ ) after the merger stays below $3 - 4$ times the nuclear-matter density ( $n_{0}$ ), the characteristic stiffening of the QHC models in that density range results in a lower $f_{2}$ than that computed for the underlying hadronic EOS and thus also than that for EOSs with a 1PT, (ii) for higher-mass binaries, where $n_{max}$ may exceed $4 - 5 n_{0}$ depending on the EOS model, whether $f_{2}$ in QHC models is higher or lower than that in the underlying hadronic model depends on the height of the sound-speed peak. Comparing the values of $f_{2}$ for different EOSs and BNS masses gives important clues on how to discriminate different types of quark dynamics in the high-density end of EOSs and is relevant to future kilohertz GW observations with third-generation GW detectors.
↳ astro-ph.HEgr-qcnucl-thPRL(2022)·93 citations
10
Snowmass White Paper: New ideas for many-body quantum systems from string theory and black holes
Mike Blake🇬🇧 · Yingfei Gu🇺🇸 · Sean A. Hartnoll🇬🇧 · Hong Liu🇺🇸 · Andrew Lucas🇺🇸 · Krishna Rajagopal🇺🇸 · Brian Swingle🇺🇸 · Beni Yoshida🇨🇦
During the last two decades many new insights into the dynamics of strongly coupled quantum many-body systems have been obtained using gauge/gravity duality, with black holes often playing a universal role. In this white paper we summarize the results obtained and offer some outlook for future developments, including the ongoing mutually beneficial feedback loop with the study of more general, not necessarily holographic, quantum many-body systems.
↳ hep-thcond-mat.str-elnlin.CDnucl-th+120 citations
11
Special Issue on Advances in Chiral Quark Models
Jorge Segovia🇪🇸
The number of exotic candidates in both light- and heavy-quark hadron sectors has increased dramatically since the discovery by the Belle Collaboration of the so-called $X (3872)$ in 2003. It is clear that the simple quark model picture needs an extension and thus the last twenty years have witnessed an explosion of related theoretical and experimental activity. The ultimate goal of theory is to describe the properties of exotic states from the first principles of Quantum Chromodynamics (QCD), which is the non-Abelian Quantum Field Theory that describes the strong interaction. However, since this task is quite challenging, a more modest goal to start with is the development of QCD-motivated phenomenological models that specify the colored constituents, how they are clustered, and the forces between them. This Special Issue invited contributions reporting recent advances of phenomenological quark models in the study of hadron's spectrocopy, structure, and interactions, paying special attention to the exotic candidates but without losing sight of the conventional states. In response to the call for papers, and after a comprehensive peer review process, 8 articles qualified for acceptance in the final edition of the Special Issue. The authors are from geographically distributed countries such as Spain, South Africa, Ghana, China, Brazil, Argentina. This reflects the impact of the proposed topic and the effective organization of the guest editorial team of this Special Issue.
↳ hep-phhep-exhep-latnucl-ex+1Symmetry(2021)·0 citations
12
Compositeness of S-wave weakly-bound states from next-to-leading order Weinberg's relations
M. Albaladejo🇪🇸 · J.Nieves🇪🇸
We discuss a model-independent estimator of the likelihood of the compositeness of a shallow S-wave bound or virtual state. The approach is based on an extension of Weinberg's relations in Phys. Rev. 137, B672 (1965) and it relies only on the proximity of the energy of the state to the two-hadron threshold to which it significantly couples. The scheme only makes use of the experimental scattering length and the effective range low energy parameters, and it is shown to be fully consistent for predominantly molecular hadrons. As explicit applications, we analyse the case of the deuteron, the $^{1} S_{0}$ nucleon-nucleon virtual state and the exotic $D_{s 0}^{*} (2317)^{\pm}$ , and find strong support to the molecular interpretation in all cases. Results are less conclusive for the $D_{s 0}^{*} (2317)^{\pm}$ , since the binding energy of this state is significantly higher than that of the deuteron, and the approach employed here is at the limit of its applicability. We also qualitatively address the case of the recently discovered $T_{cc}^{+}$ state, within the isospin limit to avoid the complexity of the very close thresholds $D^{0} D^{*+}$ and $D^{+} D^{* 0}$ , which could mask the ingredients of the approach proposed in this work.
↳ hep-phnucl-thEPJC(2022)·55 citations

Affiliations

first authorsco-authorsvia INSPIRE