Nuclear Theory·nucl-th

Wednesday·December 27, 2023

20 papers—11 primary·9 cross-listed

01
[Submitted on 14 Dec 2023]
Non-Markovian character and irreversibility of real-time quantum many-body dynamics
Aurel Bulgac🇺🇸 · Matthew Kafker🇺🇸 · Ibrahim Abdurrahman🇺🇸 · Ionel Stetcu🇺🇸
The presence of pairing correlations within the time-dependent density functional theory (TDDFT) extension to superfluid systems, is tantamount to the presence of a quantum collision integral in the evolution equations, which leads to an obviously non-Markovian behavior of the single-particle occupation probabilities, unexpected in a traditional quantum extension of kinetic equations. The quantum generalization of the Boltzmann equation, based on a collision integral in terms of phase-space occupation probabilities, is the most used approach to describe nuclear dynamics and which by construction has a Markovian character. By contrast, the extension of TDDFT to superfluid systems has similarities with the Baym and Kadanoff kinetic formalism, which however is formulated with much more complicated evolution equations with long-time memory terms and non-local interactions. The irreversibility of quantum dynamics is properly characterized using the canonical wave functions/natural orbitals, and the associated canonical occupation probabilities, which provide the smallest possible representation of any fermionic many-body wave function. In this basis, one can evaluate the orbital entanglement entropy, which is an excellent measure of the non-equilibrium dynamics of an isolated system. To explore the phenomena of memory effects and irreversibility, we investigate the use of canonical wave functions/natural orbitals in nuclear many-body calculations, assessing their utility for static calculations, dynamics, and symmetry restoration. As the number of single-particle states is generally quite large, it is highly desirable to work in the canonical basis whenever possible, preferably with a cutoff. We show that truncating the number of canonical wave functions can be a valid approach in the case of static calculations, but that such a truncation is not valid for time-dependent calculations...
Comments:
23 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th); Statistical Mechanics (cond-mat.stat-mech)
arXiv:
2312.14962 [pdf]
PRC(2024)·9 citations
02
[Submitted on 22 Dec 2023]
Toward Initial Conditions of Conserved Charges
Patrick Carzon🇺🇸
At top collider energies where baryon stopping is negligible, the initial state of heavy ion collisions is overall charge neutral and predominantly composed of gluons. Nevertheless, there can also be significant local fluctuations of the baryon number, strangeness, and electric charge densities about zero, perturbatively corresponding to the production of quark/antiquark pairs. These previously ignored local charge fluctuations can permit the study of charge diffusion in the quark-gluon plasma (QGP), even at top collider energies. In this paper we present a new model denoted \code{iccing} (Initial Conserved Charges in Nuclear Geometry) which can reconstruct the initial conditions of conserved charges in the QGP by sampling a ( $g \to q q ˉ$ ) splitting probability over the initial energy density. We find that the new charge distributions generally differ from the bulk energy density; in particular, the strangeness distribution is significantly more eccentric than standard bulk observables and appears to be associated with the geometry of hot spots in the initial state. The new information provided by these conserved charges opens the door to studying a wealth of new charge- and flavor-dependent correlations in the initial state and ultimately the charge transport parameters of the QGP.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2312.15008 [pdf]
0 citations
03
[Submitted on 22 Dec 2023]
Interference of resonances in two-proton emission of $^{16}$ Ne
Tomohiro Oishi · Masaaki Kimura
We investigate the two-proton ( $2 p$ ) emission from $^{16}$ Ne with the time-dependent $^{14}$ O $+ p + p$ three-body calculations. Two $0^{+}$ resonances are suggested to participate. For the $0_{1}^{+}$ resonance, the true emission of the spatially localized two protons is dominant, if the single-particle $s_{1/2}$ resonance locates above the $2 p$ energy. By evaluating a time-evolution probability, the $0_{2}^{+}$ resonance is suggested at $≅ 3$ MeV from the $2 p$ threshold. The inclusion of $0_{2}^{+}$ resonance makes the true- $2 p$ ~emission more dominant in the time-dependent calculations.
Comments:
11 pages, 13 figures, 5 tables, revised for resubmitting
Subjects:
Nuclear Theory (nucl-th); nlin.CD (nlin.CD); Nuclear Experiment (nucl-ex)
arXiv:
2312.15017 [pdf]
PRC(2025)·3 citations
04
[Submitted on 24 Dec 2023]
New quantification of symmetry energy from neutron skin thicknesses of $^{48}$ Ca and $^{208}$ Pb
Rong An · Shuai Sun · Li-Gang Cao · Feng-Shou Zhang
Precise knowledge of the nuclear symmetry energy can be tentatively calibrated through multimessenger constraints. The neutron skin thickness of a heavy nucleus is one of the most sensitive indicators for probing the isovector components of effective interactions in asymmetric nuclear matter. Recent studies have suggested that the experimental data from the CREX and PREX2 Collaborations are not mutually compatible within existing nuclear models. In this study, we review the quantification of the slope parameter of symmetry energy $L$ from the neutron skin thicknesses of $^{48}$ Ca and $^{208}$ Pb. Skyrme energy density functionals classified by various isoscalar incompressibility coefficients $K$ are employed to evaluate the bulk properties of finite nuclei. The calculated results suggest that the slope parameter $L$ deduced from $^{208}$ Pb is sensitive to the compression modulus of symmetric nuclear matter, but not that from $^{48}$ Ca. The effective parameter sets classified by $K = 220$ MeV can provide an almost overlaping range of $L$ from $^{48}$ Ca and $^{208}$ Pb.
Comments:
13 pages, 3 figures and 2 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2312.15434 [pdf]
Nucl.Sci.Tech.(2024)·14 citations
05
[Submitted on 24 Dec 2023]
The imprint of conservation laws on correlated particle production
Peter Braun-Munzinger🇩🇪 · Krzysztof Redlich🇵🇱 · Anar Rustamov🇩🇪 · Johanna Stachel🇩🇪
The study of event-by-event fluctuations of net-baryon number in a subspace of full phase space is a promising direction for deciphering the structure of strongly interacting matter created in head-on collisions of relativistic heavy nuclei. Such fluctuations are generally suppressed by exact baryon number conservation. Moreover, the suppression is stronger if baryon number is conserved locally. In this report we present a conceptually new approach to quantify correlations in rapidity space between baryon-antibaryon, baryon-baryon, and antibaryon-antibaryon pairs and demonstrate their impact on net-baryon number fluctuations. For the special case of Gaussian rapidity distributions, we use the Cholesky factorization of the covariance matrix, while the general case is introduced by exploiting the well-known Metropolis and Simulated Annealing methods. The approach is based on the use of the canonical ensemble of statistical mechanics for baryon number and can be applied to study correlations between baryons as well as strange and/or charm hadrons. It can also be applied to describe relativistic nuclear collisions leading to the production of multi-particle final states. One application of our method is the search for formation of proton clusters at low collision energies emerging as a harbinger of the anticipated first-order chiral phase transition. In a first step, the results obtained are compared to the recent measurements from the CERN ALICE collaboration. Such investigations are key to explore the phase diagram of strongly interacting matter and baryon production mechanisms at energy scales from several GeV to several TeV.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2312.15534 [pdf]
JHEP(2024)·25 citations
06
[Submitted on 25 Dec 2023]
From masses and radii of neutron stars to EOS of nuclear matter through neural network
Zehan Wu · Dehua Wen
The equation of state (EOS) of dense nuclear matter is a key factor to determine the internal structure and properties of neutron stars. However, the EOS of high-density nuclear matter has great uncertainty mainly because the terrestrial nuclear experiments cannot reproduce matter as dense as that in the inner core of a neutron star. Fortunately, continuous improvements in astronomical observations of neutron stars provide the opportunity to inversely constrain the EOS of high-density nuclear matter. A number of methods have been proposed to implement this inverse constraint, such as the Bayesian analysis algorithm, the Lindblom's approach, and so on. Neural network algorithm is an effective new method developed in recent years. By employing a set of isospin-dependent parametric EOSs as the training sample of neural network algorithm, we set up an effective way to reconstruct the EOS with relative accuracy through a few mass-radius data. Based on the obtained neural network algorithms and according to the NICER observations on masses and radii of neutron stars with assumed precision, we get the inversely constrained EOS and further calculate the corresponding macroscopic properties of the neutron star. The results are basically consistent with the constraint on EOS from the Huth $e t a l .$ based on Bayesian analysis. Moreover, the results show that even though the neural network algorithm was obtained by using the finite parameterized EOS as the training set, it is valid for any rational parameter combination of the parameterized EOS model.
Comments:
13 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
2312.15629 [pdf]
CPC(2024)·4 citations
07
[Submitted on 25 Dec 2023]
Saturation of nuclear matter in the relativistic Brueckner Hatree-Fock approach with a leading order covariant chiral nuclear force
Wei-Jiang Zou🇨🇳 · Jun-Xu Lu🇨🇳 · Peng-Wei Zhao🇨🇳 · Li-Sheng Geng🇨🇳 · Jie Meng🇨🇳
Nuclear saturation is a crucial feature in nuclear physics that plays a fundamental role in understanding various nuclear phenomena, ranging from properties of finite nuclei to those of neutron stars. However, a proper description of nuclear saturation is highly nontrivial in modern nonrelativistic~\textit{ab initio}~studies because of the elusive three-body forces. In this letter, we calculate the equation of state for nuclear matter in the relativistic Brueckner-Hartree-Fock (RBHF) framework with the leading order covariant chiral nuclear force. We show that a simultaneous description of the nucleon-nucleon scattering data and the saturation of the symmetric nuclear matter can be achieved. In this regard, the relativistic effects nicely explain the saturation of nuclear matter. As a result, the present study based on the covariant chiral nuclear force shows that in the RBHF framework, one can achieve saturation with a leading order covariant chiral nuclear force with only two-body forces, in contrast to the vast majorities of studies in the non-relativistic framework, where the next-to-next-to-leading order two-body and three-body chiral forces are needed. This study sets the foundation for studying nuclear saturation with the covariant chiral force in the RBHF framework, which allows for a systematic understanding of one of the key features of nuclear physics more microscopically.
Comments:
11 pages, 10 figures, version published in Physics Letters B
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2312.15672 [pdf]
PLB(2024)·18 citations
08
[Submitted on 25 Dec 2023]
Isospin-dependent in-medium nucleon-Delta elastic cross section
Manzi Nan🇨🇳 · Pengcheng Li🇨🇳 · Yongjia Wang🇨🇳 · Qingfeng Li🇨🇳 · Wei Zuo🇨🇳
In heavy-ion collisions at intermediate energies, the production and propagation of $Δ$ particles are crucial to understanding the nuclear equation of state and inferring the properties of nuclear matter at high densities. Based on the self-consistent relativistic Boltzmann-Uehling-Uhlenbeck (RBUU) transport theory, by introducing the isovector $ρ$ meson exchange into the effective Lagrangian and adopting the density-dependent coupling constants, the detailed expressions for isospin-dependent in-medium $N Δ \to N Δ$ elastic cross sections $σ_{N Δ}^{*}$ have been calculated. The energy and density dependence of the isospin-related $σ_{N Δ}^{*}$ as well as the total contributions of $σ$ , $ω$ and $ρ$ meson fields are analyzed. It is found that the total $σ_{N Δ}^{*}$ has a sensitive center-of-mass energy dependence at lower energies while exhibiting a slight increase as the center-of-mass energy increases. The isospin effect between different isospin-separated channels weakens as the energy and/or density increases. The isospin effect on the density- and energy-dependent in-medium $N Δ$ elastic cross sections is dominantly caused by the delicate balance of the isovector $ρ$ meson exchange.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2312.15716 [pdf]
EPJA(2024)·4 citations
09
[Submitted on 26 Dec 2023]
Effects of center-of-mass correction and nucleon anomalous magnetic moments on nuclear charge radii
Yusuke Tanimura · Myung-Ki Cheoun
Effects of the center-of-mass correction together with the nucleon electromagnetic form factors on the nuclear charge radius are systematically studied with a relativistic Hartree-Bogoliubov model. Both one- and two-body parts of the CM correction are taken into account. It is found that the one- and two-body CM corrections, and the spin-orbit effect originating from the nucleon anomalous magnetic moments are all of the same order in magnitude, and that they give sizable impacts on the charge radius from light to heavy nuclei.
Comments:
14 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2312.15983 [pdf]
PRC(2024)·5 citations
10
[Submitted on 26 Dec 2023]
Excluded volume effects in the quark-mass density-dependent model: implications for the equation of state and compact star structure
G. Lugones🇧🇷 · A. G. Grunfeld🇦🇷
We present a significant extension of the quark mass density-dependent model (QMDDM), initially revised in our prior study (Lugones and Grunfeld, Phys. Rev. D 107, 043025 (2023)), where thermodynamic inconsistencies were addressed. Our current work enriches the QMDDM by incorporating excluded volume effects, as a step towards a more realistic representation of the quark matter equation of state (EOS) at zero temperature. We introduce the concept of ``available volume'' in the Helmholtz free energy formulation, accounting for the space excluded by each quasiparticle due to its finite size or repulsive interactions. We present a methodology to modify the EOS for point-like particles, allowing for a simple and direct incorporation of excluded volume effects. This is first addressed in a simple one-flavor model and then extended to a more realistic three-flavor system, incorporating both mass and volume dependencies on the baryon number density. We examine various ansatzes for the excluded volume, ultimately adopting one that aligns with the asymptotic freedom behavior of Quantum Chromodynamics (QCD). The EOS for electrically neutral systems in chemical equilibrium is computed, focusing on self-bound and hybrid matter scenarios. We show that the incorporation of excluded volume effects renders the EOS stiffer and that excluded volume effects are essential to align the mass-radius relation of self-bound and hybrid stars with modern astrophysical constraints.
Comments:
17 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2312.16095 [pdf]
PRD(2024)·6 citations
11
[Submitted on 26 Dec 2023]
Microscopic Optical Potentials from Chiral Forces and Ab Initio Nuclear Densities
Carlotta Giusti · Matteo Vorabbi · Paolo Finelli
We derived microscopic optical potentials (OPs) for elastic nucleon-nucleus scattering within the framework of chiral effective field theories at the first-order term of the spectator expansion of the Watson multiple-scattering theory and adopting the impulse approximation. Our OPs are derived by folding ab initio nuclear densities with a nucleon-nucleon NN t matrix computed with a consistent chiral interaction. The results of our OPs are in good agreement with the experimental data. Recent achievements of our work are reviewed in this contribution.
Comments:
10 pages 4 figures Proceedings of the 40th International Workshop in Nuclear Theory, IWNT-202, Rila Mountains, Bulgaria3
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2312.16157 [pdf]
Nucl.Theor.(2023)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE