Nuclear Theory·nucl-th

Tuesday·November 12, 2024

15 papers—8 primary·7 cross-listed

01
Elliptic and quadrangular flow of protons in the high baryon density region
Shaowei Lan🇨🇳 · Zuowen Liu🇨🇳 · Like Liu🇨🇳 · Shusu Shi🇨🇳
The collective flow provides valuable insights into the anisotropic expansion of particles produced in heavy-ion collisions and is sensitive to the equation of the state of nuclear matter in high-baryon-density regions. In this paper, we use the hadronic transport model SMASH to investigate the elliptic flow ( $v_{2}$ ), quadrangular flow ( $v_{4}$ ), and their ratio ( $v_{4} / v_{2}^{2}$ ) in Au+Au collisions at high baryon density. Our results show that the inclusion of baryonic mean-field potential in the model successfully reproduces experimental data from the HADES experiment, indicating that baryonic interactions play an important role in shaping anisotropic flow. In addition to comparing the transverse momentum ( $p_{T}$ ), rapidity, and centrality dependence of $v_{4} / v_{2}^{2}$ between HADES data and model calculations, we also explore its time evolution and energy dependence across $s_{N N} =$ 2.4 to 4.5 GeV. While the ratio $v_{4} / v_{2}^{2}$ for high- $p_{T}$ particles approaches 0.5, which aligns with expectations from hydrodynamic behavior, we emphasize that this result primarily reflects agreement with the HADES measurements rather than a definitive indication of ideal fluid behavior. These findings contribute to understanding the early-stage dynamics in heavy-ion collisions at high baryon density.
nucl-thUniverse(2025)·1 citation
02
Imprints of high-density nuclear symmetry energy on the crustal fraction of neutron star moment of inertia
Nai-Bo Zhang · Bao-An Li
The density dependence of nuclear symmetry energy $E_{sym} (ρ)$ remains the most uncertain aspect of the equation of state (EOS) of supradense neutron-rich nucleonic matter. Implications of observational crustal fraction of neutron star (NS) moment of inertia $Δ I / I$ on the $E_{sym} (ρ)$ are examined in the present work, utilizing an isospin-dependent parameterization of NS EOS. We find that symmetry energy parameters significantly influence the $Δ I / I$ , while the EOS of symmetric nuclear matter has a negligible effect. An increase in the slope $L$ and skewness $J_{sym}$ of symmetry energy results in a larger $Δ I / I$ , whereas an increase in the curvature $K_{sym}$ leads to a reduction in $Δ I / I$ . Additionally, we discuss the imprints of observational $Δ I / I$ on the symmetry energy for NSs with masses of 1.0 M $_{⊙}$ or 1.4 M $_{⊙}$ . Our results indicate that the $Δ I / I$ has the potential to set a lower limit of symmetry energy at densities exceeding $3 ρ_{0}$ , particularly when $L$ is constrained to values less than $60$ MeV, thereby enhancing our understanding of supradense NS matter.
nucl-thParticles(2025)·2 citations
03
Divergence and resummation of the moment expansion for an ultrarelativistic gas in Bjorken flow
Caio V. P. de Brito🇧🇷 · David Wagner🇮🇹 · Gabriel S. Denicol🇧🇷 · Dirk H. Rischke🇩🇪
In this letter, we demonstrate for the first time that the moment expansion for an ultrarelativistic gas undergoing Bjorken flow diverges. We then show how this series can be resummed using the Borel-Padé method and use this to determine the single-particle distribution function of the gas. Finally, we compare the exact resummed solution of the single-particle distribution function with solutions of the Boltzmann equation in the hydrodynamic limit and verify that the system displays considerable deviations from local equilibrium.
nucl-thhep-thPRD(2026)·7 citations
04
Finite nuclei in an extended Nambu-Jona-Lasinio model
Cheng-Jun Xia🇨🇳 · Yu-Ting Rong🇨🇳 · Ting-Ting Sun🇨🇳
We propose a new theoretical framework to investigate the properties of finite nuclei based on an extended Nambu-Jona-Lasinio (eNJL) model, where the Dirac sea, the spontaneous chiral symmetry breaking, and the quark degrees of freedom are considered by extending the SU(3) NJL model and treating baryons as clusters of quarks. The eNJL model can then be readily adopted to examine the matter states ranging from baryonic matter to quark matter in a unified manner. In this work, by assuming spherically symmetric finite nuclei and neglecting the center-of-mass or rotational corrections, we systematically investigate the properties of finite nuclei based on the eNJL model with additional pairing correlations. It is found that our model generally reproduces the binding energies of the 2495 nuclei ( $A > 2$ ) from the 2016 Atomic Mass Evaluation (AME2016) with the root-mean-square deviations $5.38$ MeV. The deviations are mainly attributed to the too large shell gaps at magic numbers $N (Z) = 28$ , 50, and 82 as well as the spurious shell closures at $N (Z) = 34$ , 58, and 92. Meanwhile, the obtained charge radii of 906 nuclei are systematically smaller than the experimental values with root-mean-square deviations $0.127$ fm. In our future study, we expect to reduce the uncertainties of our predictions by carefully calibrating the density dependence of coupling constants and considering deformations with microscopic collective corrections from the nucleons in the Fermi sea and quarks in the Dirac sea.
nucl-thhep-ph0 citations
05
Non-Hermitian quantum mechanics approach for extracting and emulating continuum physics based on bound-state-like calculations: Detailed description
Xilin Zhang🇺🇸
This work applies a reduced basis method to study the continuum physics of a finite quantum system -- either few or many-body. Specifically, I develop reduced-order models, or emulators, for the underlying inhomogeneous Schrödinger equation and train the emulators against the equation's bound-state-like solutions at complex energies. The emulators rapidly and accurately interpolate and extrapolate the matrix elements of the Hamiltonian resolvent operator (Green's function) across a parameter space that includes both complex energy and other real-valued physical inputs in the Schrödinger equation. The spectra, discretized and compressed as the result of emulation, and the associated resolvent matrix elements (or amplitudes), have the defining characteristics of non-Hermitian quantum mechanics calculations, featuring complex eigenenergies with negative imaginary parts and branch cuts moved below the real axis in the complex energy plane. Therefore, one now has a method that extracts continuum physics from bound-state-like calculations and emulates those extractions in the input parameter space. Building on a prior Letter [arXiv:2408.03309], this article provides the full theoretical details, a comprehensive analysis of the method's performance, and a brief discussion of how it can be coupled with existing continuum approaches to perform emulations in their input parameter spaces.
nucl-thhep-phphysics.atom-phphysics.chem-ph+1PRC(2025)·11 citations
06
Collective modes in relativistic cold asymmetric nuclear matter within the covariant Vlasov approach
Aziz Rabhi · Olfa Boukari · Sidney S. Avancini · Constança Providência
A covariant relativistic approach based on the Vlasov equation is applied to the study of infinite asymmetric nuclear matter. We use several Walecka-type hadronic models and obtain the dispersion relations for the longitudinal modes. The isovector and isoscalar collective modes are determined for a wide range of densities as a function of isospin asymmetry and momentum transfer within a set of eleven relativistic mean field models with different nuclear matter properties. Special attention is given to beta-equilibrium matter. It is shown that the possible propagation of isoscalar and isovector-like modes depends directly on the density dependence of the symmetric nuclear matter equation of state and of the symmetry energy, with a stiff equation of state favouring the propagation of isoscalar like collective modes at high densities, and a stiff symmetry energy defining the behavior of the isovector like modes which propagate for densities below two times saturation density. The coupling of the nuclear modes to the electron plasmon is also discussed.
nucl-thastro-ph.HEastro-ph.IMPRC(2025)·2 citations
07
Probing nuclear structure and the equation of state through pre-equilibrium dipole emission in charge-asymmetric reactions
Leonid Shvedov · Stefano Burrello · Maria Colonna · Hua Zheng
We investigate the pre-equilibrium dipole response in the charge-asymmetric reaction $^{40}$ Ca+ $^{152}$ Sm, of recent experimental interest, at several beam energies within the range $[5, 11]$ AMeV and different collision centralities. By employing Skyrme-like effective interactions for the nuclear mean field, we probe the role of the different ingredients performing theoretical calculations based on the time-dependent Hartree-Fock approach or a semi-classical transport model that also includes two-body correlations. A comparative analysis between these approaches allowed us to disentangle the role of deformation effects in the entrance channel from the ones associated with structure details of genuine quantal nature on the dipole emission. Moreover, we also investigate the impact of the occurrence of residual two-body collisions on the reaction dynamics. This study contributes to the understanding of the microscopic processes that determine the complex dynamics of low-energy heavy-ion collisions along the fusion-fission path, which is relevant to super-heavy element synthesis, unraveling interesting connections with the characteristics of the nuclear effective interaction and the associated equation of state.
nucl-thPRC(2025)·4 citations
08
Astrophysical constraints on nuclear EOSs and coupling constants in RMF models
Cheng-Jun Xia🇨🇳 · Wen-Jie Xie🇨🇳 · Mohemmedelnazier Bakhiet🇨🇳
Utilizing various astrophysical constraints on neutron star structures, we carry out a Bayesian analysis on the density-dependent behaviors of coupling constants in RMF models as well as the nuclear matter properties at supranuclear densities. The effective nucleon interactions in the isoscalar-scalar, isoscalar-vector, and isovector-vector channels are considered, where the corresponding coupling constants ( $α_{S}, α_{V}, α_{T V}$ ) are fixed by dividing entire density range into three regions with six independent parameters. In this work we focus on constraining the density-dependent point-coupling constants at supranuclear densities, while the coupling constants at subsaturation densities are derived from the covariant density functional DD-ME2. For those consistent with astrophysical observations, the coupling constants generally decrease with density and approach to small positive values at large enough densities, which qualitatively agrees with various RMF models. The posterior probability density functions and their correlations of the coupling constants and various nuclear matter properties are examined as well. At $1 σ$ level, the constrained coupling constants at density $1.5 n_{0}$ ( $2.5 n_{0}$ ) are $α_{S} = 3. 1_{- 0.05}^{+ 0.1} (1.5 5_{- 0.2}^{+ 0.85}) \times 1 0^{- 4} MeV^{- 2}$ , $α_{V} = 2. 3_{- 0.0}^{+ 0.1} (1. 3_{- 0.1}^{+ 0.55}) \times 1 0^{- 4} MeV^{- 2}$ , and $α_{T V} = 2.0 5_{- 0.4}^{+ 0} (2.0 5_{- 0.5}^{+ 0}) \times 1 0^{- 5} MeV^{- 2}$ . At larger densities, we find the lower limit of $α_{T V}$ is not well constrained, so that more extensive calculations with larger number of free parameters are necessary.
nucl-thPRD(2024)·14 citations
09
Second-order hyperfine correction to H, D, and $^{3}$ He energy levels
Krzysztof Pachucki · Vojtěch Patkóš · Vladimir A. Yerokhin
The complete second-order hyperfine-interaction correction is calculated for centroid energy levels of H, D, and $^{3}$ He atoms. For $^{3}$ He, the corrections of $- 2.075$ ~kHz and $- 0.305$ ~kHz beyond the leading hyperfine-mixing contribution are obtained for the $2^{1} S$ and $2^{3} S$ states, respectively. These results shift the nuclear charge radii difference derived from the $^{3}$ He - $^{4}$ He isotope shift and largely resolve the previously reported disagreement between the muonic and electronic helium determinations [van der Werf et al., arXiv:2306.02333 (2023); Schuhmann et al., arXiv:2305.11679 (2023)].
↳ physics.atom-phnucl-thPRA(2024)·11 citations
10
Boost-invariant spin hydrodynamics with spin feedback effects
Zbigniew Drogosz🇵🇱 · Wojciech Florkowski🇵🇱 · Natalia Łygan🇵🇱 · Radoslaw Ryblewski🇵🇱
A recently formulated extension of perfect spin hydrodynamics, which includes second-order corrections in the spin polarization tensor to the energy-momentum tensor and baryon current, is studied in the case of a one-dimensional boost-invariant expansion. The presence of second-order corrections introduces feedback from spin dynamics on the hydrodynamic background, constraining possible spin polarization configurations. However, as long as the magnitude of the spin polarization tensor remains small (below unity in natural units), the permitted spin dynamics differs very little from that found in the case without the second-order corrections.
↳ hep-phnucl-thPRC(2025)·15 citations
11
The effect of pressure anisotropy on quark stars structure in the Starobinsky model
Takol Tangphati🇹🇭 · İzzet Sakallı🇨🇱 · Ayan Banerjee🇿🇦 · Anirudh Pradhan🇮🇳
The structure and stability of quark stars (QSs) made of interacting quark matter are discussed in this study, taking color superconductivity and perturbative QCD corrections into account. By combining this EoS with the Tolman-Oppenheimer-Volkoff (TOV) equations, we explore the mass-radius ( $M - R$ ) relations of QSs. The analysis is conducted within the framework of $R^{2}$ gravity, where the gravity model is described by $f (R) = R + a R^{2}$ . Our primary goal is to investigate how variations in the $R^{2}$ gravity parameter $a$ affect the mass-radius and mass-central density ( $M - ρ_{c}$ ) relationships of QSs. Furthermore, we study the dynamical stability of these stars by analyzing the impact of anisotropy parameters $β$ and the interaction parameter $λ$ derived from the EoS, on their stability. Our results demonstrate that the presence of pressure anisotropy plays a significant role in increasing the maximum mass of QSs, with potential implications for the existence of super-massive pulsars. These findings are in agreement with recent astronomical observations, which suggest the possibility of neutron stars exceeding $2 M_{⊙}$ .
↳ hep-thastro-ph.HEgr-qcnucl-thCPC(2025)·8 citations
12
Dynamical constraints on pseudo-gauge transformations
Zbigniew Drogosz🇵🇱 · Wojciech Florkowski🇵🇱 · Mykhailo Hontarenko🇵🇱 · Radoslaw Ryblewski🇵🇱
Classical pseudo-gauge transformations are discussed in the context of hydrodynamic models of heavy-ion collisions. A decomposition of the pseudo-gauge transformation into Lorentz-invariant tensors is made, which allows for better interpretation of its physical consequences. For pseudo-gauge transformations connecting two symmetric energy-momentum tensors, we find that the super-potential $Φ^{λ μν}$ must obey a conservation law of the form $\partial_{λ} Φ^{λ μν} = 0$ . This equation, referred to below as the STS condition, represents a constraint that is hardly possible to be satisfied for tensors constructed out of the basic hydrodynamic variables such as temperature, baryon chemical potential, and the hydrodynamic flow. However, in a special case of the boost-invariant flow, the STS condition is automatically fulfilled and a non-trivial residual pseudo-gauge transformation defined by a single scalar field is allowed. In this case the bulk and shear viscosity coefficients become pseudo-gauge dependent; however, their specific linear combination appearing in the equations of motion remains pseudo-gauge invariant. This finding provides new insights into the role of pseudo-gauge transformations and pseudo-gauge invariance.
↳ hep-phnucl-thPLB(2025)·12 citations
13
Mass measurements of neutron-rich nuclides using the Canadian Penning Trap to inform predictions in the $r$ -process rare-earth peak region
D. Ray · N. Vassh · B. Liu · A.A. Valverde · M. Brodeur · J.A. Clark · G.C. McLaughlin · M.R. Mumpower · R. Orford · W.S. Porter · G. Savard · K. S. Sharma and 16 other authors
Studies aiming to determine the astrophysical origins of nuclei produced by the rapid neutron capture process ( $r$ process) rely on nuclear properties as inputs for simulations. The solar abundances can be used as a benchmark for such calculations, with the $r$ -process rare-earth peak (REP) around mass number ( $A$ ) 164 being of special interest due to its presently unknown origin. With the advancement of rare isotope beam production over the last decade and improvement in experimental sensitivities, many of these REP nuclides have become accessible for measurement. Masses are one of the most critical inputs as they impact multiple nuclear properties, namely the neutron-separation energies, neutron capture rates, $β$ -decay rates, and $β$ -delayed neutron emission probabilities. In this work, we report masses of 20 neutron-rich nuclides (along the Ba, La, Ce, Pr, Nd, Pm, Gd, Dy and Ho isotopic chains) produced at the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory. The masses were measured with the Canadian Penning trap (CPT) mass spectrometer using the Phase-Imaging Ion-Cyclotron-Resonance (PI-ICR) technique. We then use these new masses along with previously published CPT masses to inform predictions for a Markov Chain Monte Carlo (MCMC) procedure aiming to identify the astrophysical conditions consistent with both solar data and mass measurements. We show that the MCMC responds to this updated mass information, producing refined results for both mass predictions and REP abundances.
↳ nucl-exnucl-th5 citations
14
Heavy Flavor Production at the Large Hadron Collider: A Machine Learning Approach
Raghunath Sahoo🇮🇳
Charmonia suppression has been considered as a smoking gun signature of quark-gluon plasma. However, the Large Hadron Collider has observed a lower degree of suppression as compared to the Relativistic Heavy Ion Collider energies, due to regeneration effects in heavy-ion collisions. Though proton collisions are considered to be the baseline measurements to characterize a hot and dense medium formation in heavy-ion collisions, LHC proton collisions with its new physics of heavy-ion-like QGP signatures have created new challenges. To understand this, the inclusive charmonia production at the forward rapidities in the dimuon channel is compared with the corresponding measurements in the dielectron channel at the midrapidity as a function of final state charged particle multiplicity. None of the theoretical models quantitatively reproduce the experimental findings leaving out a lot of room for theory. To circumvent this and find a reasonable understanding, we use machine learning tools to separate prompt and nonprompt charmonia and open charm mesons using the decay daughter track properties and the decay topologies of the mother particles. Using PYTHIA8 data, we train the machine learning models and successfully separate prompt and nonprompt charm hadrons from the inclusive sample to study various directions of their production dynamics. This study enables a domain of using machine learning techniques, which can be used in the experimental analysis to better understand charm hadron production and build possible theoretical understanding.
↳ hep-phhep-exnucl-exnucl-th0 citations
15
A Quantum Annealing Protocol to Solve the Nuclear Shell Model
Emanuele Costa🇪🇸 · Axel Perez-Obiol🇪🇸 · Javier Menendez🇪🇸 · Arnau Rios🇪🇸 · Artur Garcia-Saez🇪🇸 · Bruno Julia-Diaz🇪🇸
The nuclear shell model accurately describes the structure and dynamics of atomic nuclei. However, the exponential scaling of the basis size with the number of degrees of freedom hampers a direct numerical solution for heavy nuclei. In this work, we present a quantum annealing protocol to obtain nuclear ground states. We propose a tailored driver Hamiltonian that preserves a large gap and validate our approach in a dozen nuclei with basis sizes up to $1 0^{5}$ using classical simulations of the annealing evolution. We explore the relation between the spectral gap and the total time of the annealing protocol, assessing its accuracy by comparing the fidelity and energy relative error to classical benchmarks. While the nuclear Hamiltonian is non-local and thus challenging to implement in current setups, the estimated computational cost of our annealing protocol on quantum circuits is polynomial in the single particle basis size, paving the way to study heavier nuclei.
↳ quant-phnucl-thSciPost Phys.(2025)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE