Nuclear Theory·nucl-th

Tuesday·July 22, 2025

17 papers—8 primary·9 cross-listed

01
Spectral BBGKY: a scalable scheme for nonlinear Boltzmann and correlation kinetics
Xingjian Lu🇨🇳 · Shuzhe Shi🇨🇳
The Bogoliubov-Born-Green-Kirkwood-Yvon (BBGKY) hierarchy provides a time-reversal-symmetric framework for describing the nonequilibrium evolution of many-body systems. Despite the success of Boltzmann-based numerical approaches, systematically extending beyond this lowest-order truncation to the full nonlinear BBGKY hierarchy remains a major challenge. Moreover, even at the Boltzmann level, accurately treating the nonlinear collision term still presents significant difficulties. Here we propose the spectral BBGKY hierarchy, an analytically equivalent and numerically tractable reformulation of the conventional BBGKY hierarchy. The spectral formulation reduces the original 6n-dimensional phase-space problem to the evolution of spectral coefficients over the 3n-dimensional coordinate space. We also develop an analytic scheme for computing the collision integrals, which achieves high accuracy and removes the need for ensemble averaging over repeated stochastic evolutions from the same initial state. The scheme evaluates the full eight-fold integral exactly for massless particles, and reduces it to a three-fold one for massive particles. The validity of the spectral BBGKY hierarchy is verified through conservation law analysis, comparison with an analytical solution, convergence tests, and analysis of spectral coefficient leakage. At minimal truncation, the spectral BBGKY yields a spectral nonlinear Boltzmann equation that captures full dynamics with a computational cost comparable to that of linearized approaches. When extended to higher-order truncations, the spectral BBGKY hierarchy provides a flexible framework for studying multiparticle correlations. This framework advances our ability to investigate the early thermalization puzzle in relativistic heavy-ion collisions and to elucidate the applicability of hydrodynamics at remarkably early stages of quark-gluon plasma evolution.
nucl-thcond-mat.stat-mechhep-phPRC(2026)·7 citations
02
Probing of EoS with clusters and hypernuclei
Yingjie Zhou🇩🇪 · Susanne Glässel🇩🇪 · Yue-Hang Leung🇩🇪 · Viktar Kireyeu🇷🇺 · Jiaxing Zhao🇩🇪 · Hui Liu🇨🇳 · Christoph Blume🇩🇪 · Iouri Vassiliev🇩🇪 · Vadim Voronyuk🇷🇺 · Michael Winn🇫🇷 · Norbert Herrmann🇩🇪 · Yaping Wang🇨🇳 and 3 other authors
The study of the nuclear equation-of-state (EoS) is a one of the primary goals of experimental and theoretical heavy-ion physics. The comparison of recent high statistics data from the STAR Collaboration with transport models provides a unique possibility to address this topic in a yet unexplored energy domain. Employing the microscopic N-body Parton-Hadron-Quantum-Molecular Dynamics (PHQMD) transport approach, which allows to describe the propagation and interactions of hadronic and partonic degrees of freedom including cluster and hyper-nucleus formation and dynamics, we investigate the influence of different EoS on bulk observables, the multiplicity, $p_{T}$ and rapidity distributions of protons, $Λ$ s and clusters up to A=4 as well as their influence on the collective flow. We explore three different EoS: two static EoS, dubbed 'soft' and 'hard', which differ in the compressibility modulus, as well as a soft momentum dependent EoS. We find that a soft momentum dependent EoS reproduces most baryon and cluster observables, including the flow observables, quantitatively, however, hard EOS show a similar trend.
nucl-thhep-phPRC(2026)·11 citations
03
Deciphering the dynamics of nuclear collisions with elongated structure of $^{20}$ Ne
Deependra Sharma🇮🇳 · Arpit Singh🇮🇳 · Sadhana Dash🇮🇳
We investigate the role of intrinsic nuclear geometry of $^{20}$ Ne nucleus in particle production in small collision systems. Discrete geometrical representations of $^{20}$ Ne, including bi-pyramidal $α$ -cluster structure in two different configurations along with NLEFT configurations, are implemented within the Monte Carlo Pythia8/Angantyr framework. The resulting particle production observables in $^{20}$ Ne- $^{20}$ Ne collisions at $s_{N N}$ = 5.36 TeV are systematically compared with those obtained using conventional Woods-Saxon description as well as with the available hydrodynamic model calculations. We investigate the sensitivity of charged particle multiplicity, transverse momentum distributions and mean transverse momentum $⟨ p_{T} ⟩$ to nuclear geometry, $α$ -clustering, and orientation effects of $^{20}$ Ne nucleus. While explicit clustering and orientation dependence lead to a noticeable modifications in final state charged particle multiplicity, their impact on transverse momentum spectra and $⟨ p_{T} ⟩$ remain modest in central collisions. The results highlight the role of intrinsic nuclear geometry and specific orientation of the colliding nuclei, providing insight into the dynamics of small systems in non-hydrodynamic particle production framework.
nucl-thhep-phhep-th1 citation
04
Sources of Radial Flow Fluctuations in the Quark-Gluon Plasma
Jiangyong Jia🇺🇸
The differential radial flow fluctuation $v_{0} (p_{T})$ has emerged as a new probe of the quark-gluon plasma. However, its characteristic rise-and-fall pattern with $p_{T}$ , resembling anisotropic flow, remains unexplained. I introduce a momentum rescaling framework that factorizes $v_{0} (p_{T})$ into kinematic and dynamical components: $v_{0} (p_{T}) / v_{0} = - [d ln ⟨ n (p_{T})⟩ / d ln p_{T} + 1] \times g (p_{T})$ . The first factor, determined by spectral shape, generates the rise-and-fall pattern as the spectra transition from exponential to power-law behavior. The dynamical component $g (p_{T})$ isolates $p_{T}$ -dependent dynamics: $< 1$ signals suppressed fluctuations, $> 1$ indicates enhancement. Analysis of LHC data reveals $g (p_{T})$ deviates from unity by 20-40% in central collisions. Predictions for RHIC show that spectral shape alone generates the rise-and-fall baseline pattern with substantial energy dependence. This framework enables tighter medium property constraints by separating kinematic from dynamical effects, with broad applications to anisotropic flow and higher-order radial flow fluctuations.
nucl-thhep-phnucl-exPRL(2026)·11 citations
05
Bayesian Inference of Nuclear-Matter Density from Proton Scattering
J.C. Zamora🇺🇸
Background: Proton elastic scattering at intermediate energy is widely employed as a tool for determining the matter radius of atomic nuclei. The sensitivity of the approach relies on high-resolution measurements at small scattering angles and low-momentum transfer. Under these conditions, the Glauber multiple scattering theory accurately describes the proton-nucleus elastic cross section. Purpose: Investigate the sensitivity of the Glauber multiple scattering theory to uncertainties associated with input parameters such as the nuclear-matter density distribution and nucleon-nucleon data. Method: A joint Bayesian inference was performed using 12 angular distributions of elastic scattering at different energies on $^{58}$ Ni, $^{90}$ Zr, and $^{208}$ Pb targets. A Metropolis-Hastings algorithm was implemented to make an uncertainty quantification analysis for the input parameters used in the Glauber multiple scattering theory. Results: The experimental cross sections were fitted simultaneously using a joint Bayesian inference approach. Posterior probability density distributions of 42 input parameters were obtained from the analysis. A moderate correlation between the nuclear density parameters and the nucleon-nucleon cross sections was found. This correlation impacts the extraction of the nuclear-matter radius. Conclusions: The present analysis provided a consistent method for extracting the nuclear-matter density distribution of $^{58}$ Ni, $^{90}$ Zr, and $^{208}$ Pb from data across different incident energies. Due to the correlation of the nucleon-nucleon cross sections with the other input parameters, a constrained Bayesian inference using free nucleon-nucleon cross section data was performed. The nuclear-matter radii obtained from the analysis are in good agreement with multiple results reported in the literature
nucl-thnucl-exPRC(2025)·0 citations
06
Shell model description of the $N = 82$ isotonic chain with a new effective interaction
Y. X. Yu · Q. Y. Chen · Chong Qi · G. J. Fu
In this work, we present a systematic study of low-lying states and electromagnetic properties of the semi-magic $N = 82$ isotonic chain with proton number $Z = 51$ -77, using the full configuration interaction shell model with a newly developed high-quality effective interaction. The calculations are performed in a large model space that includes all proton orbitals between $Z = 50$ and 82: $0 g_{7/2}$ , $1 d_{5/2}$ , $1 d_{3/2}$ , $2 s_{1/2}$ , and $0 h_{11/2}$ . The effective interaction is derived through the principal component analysis approach, starting from 160 two-body matrix elements and 5 single-particle energies and considering up to 30 degrees of freedom. Those are optimized by fitting to 204 available experimental energy levels. The resulting root-mean-square deviation is as low as 102 keV. The new interaction successfully reproduces the binding energies, low-lying spectra, electric quadrupole transition probabilities $B (E 2)$ , and magnetic dipole moments across both even-even and odd-mass isotones. The nuclear structure of low-lying states is analyzed in detail. Additionally, predictions are made for several more proton-rich nuclei beyond current experimental reach, including $^{155} Ta$ , $^{156} W$ , $^{157} Re$ , $^{158} Os$ , and $^{159} Ir$ .
nucl-thPRC(2026)·2 citations
07
Toward scalable quantum computations of atomic nuclei
Chenyi Gu🇺🇸 · Matthias Heinz🇺🇸 · Oriel Kiss🇨🇭 · Thomas Papenbrock🇺🇸
We solve the nuclear two-body and three-body bound states via quantum simulations of pionless effective field theory on a lattice in position space. While the employed lattice remains small, the usage of local Hamiltonians including two- and three-body forces ensures that the number of Pauli terms scales linearly with increasing numbers of lattice sites. We use an adaptive ansatz grown from unitary coupled cluster theory to parametrize the ground states of the deuteron and $^{3}$ He, compute their corresponding energies, and analyze the scaling of the required computational resources. Our quantum simulations reproduce exact benchmarks for $^{2}$ H and $^{3}$ He within 100 keV, requiring at most 30 layers in the ansatz and thus resulting in modest circuit depths. Additionally, we find the number of shots required to reach a given precision scales linearly in the lattice size and more mildly in the system size. Based on the agreement with exact benchmarks and mild scaling, we conclude that this can be an efficient, scalable approach for quantum computations of nuclear ground states, particularly to prepare initial states for quantum phase estimation or other filtering algorithms.
nucl-thquant-phPRC(2026)·14 citations
08
Radiative corrections to the parity-violating spin asymmetry
D.H.Jakubassa-Amundsen🇩🇪 · X.Roca-Maza🇪🇸
The parity-violating spin asymmetry Apv for elastic electron scattering from spin-zero nuclei, together with its QED corrections, is evaluated non-perturbatively within the phase-shift analysis. Dispersion corrections, taking into account low-lying transient nuclear excitations, are estimated with the help of the lowest-order $γ Z$ box diagrams. Collision energies between 5 $-$ 500 MeV are considered, and results are provided for the $^{12}$ C and $^{208}$ Pb target nuclei. In addition, we have evaluated Apv at GeV energies and small scattering angles -- relevant for the Pb Radius Experiment (PREx) -- revealing that the low-lying nuclear excited states give no measurable dispersive contribution. However, they are important at lower energies and backward angles.
nucl-thnucl-exPRC(2026)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE