Longitudinal particle production in heavy-ion collisions is influenced both by preferential emission from participating nucleons and by the breakup of spectator matter, yet quantifying these effects experimentally remains challenging. We introduce a Pearson correlation between spectator and charged-particle forward-backward asymmetries as an experimental probe of these phenomena. Using $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200$ GeV simulated with A Multi-Phase Transport model, we validate that this correlator provides a robust, pseudorapidity-differential measure of the influence of preferential emission on the longitudinal structure of particle production. We further demonstrate that the correlation strength is sensitive to fluctuations in spectator number, which in experiments arise from evaporation and fragmentation of the spectator remnants. The proposed observable therefore offers a data-driven handle for constraining models of preferential emission and spectator breakup, thereby improving our understanding of the mechanisms that shape the final-state longitudinal distributions in heavy-ion collisions.

We perform ($2+1$)-dimensional simulations of viscous anisotropic hydrodynamics (VAH) under boost-invariant and conformal conditions. Comparing both VAH and traditional viscous hydrodynamics with kinetic theory in the relaxation-time approximation as the underlying microscopic theory, we show that VAH provides a superior description of the evolution across a wide range of opacity, effectively extending the applicability of hydrodynamic modeling. Our results demonstrate VAH's potential for describing collective flow in small systems where traditional hydrodynamics faces challenges.

In this work, a microscopic effective nucleon-nucleon interaction based on the Dirac-Brueckner-Hartree-Fock $G$ matrix starting from a bare nucleon-nucleon interaction is used to explore the $\alpha$-decay half-lives of nuclei above doubly magic nucleus ${}^{100}\mathrm{Sn}$. Specifically, the $\alpha$-nucleus potential is constructed by doubly folding the effective nucleon-nucleon interaction with respect to the density distributions of both the $\alpha$-cluster and the daughter nucleus. Moreover, the $\alpha$-cluster preformation factor is extracted by a cluster formation model. It is shown that the calculated half-lives within the Wentzel-Kramers-Brillouin approximation can reproduce the experimental data well. Then, the $\alpha$-decay half-lives that are experimentally unavailable for the nuclei around ${}^{100}\mathrm{Sn}$ are predicted, which are helpful for searching for the new candidates of $\alpha$ decay in future experiments. In addition, by analyzing the proton-neutron correlation energies and two proton–two neutron correlation energies of nuclei above doubly magic nuclei ${}^{100}\mathrm{Sn}$ and ${}^{208}\mathrm{Pb}$, the $\alpha$-cluster preformation factor evolution with $N$ is explained. It is found that the two proton–two neutron interaction plays a more important role in an $\alpha$-cluster preformation than the proton-neutron interaction. However, the two proton–two neutron correlation energies of nuclei near ${}^{100}\mathrm{Sn}$ are much larger than those near ${}^{208}\mathrm{Pb}$, which results in a larger preformation factor for the nuclei around ${}^{100}\mathrm{Sn}$. Meanwhile, the proton-neutron interaction results in the odd-even effect of the $\alpha$-cluster preformation factor.

In this paper, we revisit the phenomenological pairing plus multipole Hamiltonian based on effective two-body matrix elements of the shell-model Hamiltonian for the $sd, pf, f_{5}p{g}_9$ and $jj56$ shells, with the procedure introduced by Dufour and Zuker [Phys. Rev. C 54, 1641 (1996)]. In addition to the monopole terms related to the bulk properties, the conventional pairing and quadrupole interactions are seen to be the most important components in the phenomenological shell-model Hamiltonian, as pointed out previously. The octupole interaction is found to play an important role in larger shells, i.e., the $f_{5}p{g}_9$ and $jj56$ shells here; it is also noted that the two-body matrix elements of the phenomenological monopole, quadrupole, and hexadecapole pairing, $\langle j_1^{2}J\left|V\right|j_2^{2}J\rangle , J=0,2,4$, are repulsive if one of the $\left(j_1{j}_2\right)$ orbits is the intruder state, which conforms to those of the delta interaction and does not conform with those of the conventional pairing plus multipole Hamiltonian. We present comparisons of calculated binding energies, low-lying energy levels, $E2$ transition rates, magnetic moments, by using the two sets of interactions, namely, the effective shell model Hamiltonians and the phenomenological pairing plus multipole Hamiltonians extracted from the effective shell model interactions. The calculated results show that the energies of low-lying states and electromagnetic properties based on the effective and phenomenological Hamiltonian are well consistent with each other, and furthermore, the larger the shells the better the consistence. Therefore, these calculations justify the applicability of the phenomenological pairing plus multipole interactions, as well as the importance of the octupole interactions in larger shells, here, the $f_{5}p{g}_9$ and $jj56$ shells.

Quantum computing is one of the most promising technologies of the near future, and the simulation of quantum many-body systems is a natural application. In this work, we present classical simulations of the ground states of light atomic nuclei within the $p$ shell, from ${}^6\mathrm{He}$ to ${}^{10}\mathrm{B}$, calculated within the nuclear shell model. We compare the performance of two leading variational quantum eigensolver algorithms: the unitary coupled cluster (UCC) and the adaptive derivative-assembled pseudo-Trotter (ADAPT) methods, introducing a new metric to quantify the use of quantum resources in each simulation. We find that Slater determinants are the most useful reference states for both approaches. Our analysis suggests that ADAPT is more efficient for nuclei close to magic numbers, while UCC tends to require fewer resources toward the mid shell. This work lays the groundwork for robust benchmarking of quantum algorithms in nuclear structure studies.

We present semi-analytical solutions for the evolution of both the temperature and chemical potentials for viscous Gubser flow with conserved charges. Such a solution can be especially useful in testing numerical codes intended to simulate relativistic fluids with large chemical potentials. The freeze-out hypersurface profiles for constant energy density are calculated, along with the corresponding normal vectors, and presented as a new unit test for numerical codes. We also compare the influence of the equation of state on the semi-analytical solutions. We benchmark the newly developed smoothed particle hydrodynamics code ccake that includes both shear viscosity and three conserved charges. The numerical solutions are in excellent agreement with the semi-analytical solution and are also able to accurately reproduce the hypersurface at freeze-out.

Remler formalism is the Wigner projection of a two particle state to bound states, which is carried out when the bound state begins to exist or when one of the two particles scatters in medium. This method has been successfully applied to quarkonium production in box simulations and in heavy-ion collisions. In this study this method is extended to strongly bound states with considerable binding energies by taking into account the potential energy between heavy quark pairs in the quark-gluon plasma. We find that an attractive heavy-quark potential enhances quarkonium production and the results are consistent with those from the statistical model in box simulations, if a proper spatial cutoff is introduced to the potential to mimic quantum effects.

We derive the three-nucleon neutrinoless double-$\beta$ decay potential in a $\mathrm{\Delta }$-full chiral effective field theory through next-to-next-to-next-to leading order in Weinberg's power counting. The matrix elements of the resulting operators are computed in light nuclei using variational Monte Carlo with wave functions constructed from the Norfolk family of nuclear interactions. We find that three-nucleon corrections induce a modest quenching of the total nuclear matrix elements. We discuss model dependencies and the potential impact of these corrections on the sensitivity of experimental programs to probe lepton number violating parameters. These results provide a benchmark for many-body methods capable of reaching heavier nuclei of experimental interest.

We perform a Bayesian analysis of the neutron star (NS) equation of state (EoS) based on a wide set of Skyrme functionals, derived from previous nuclear physics inferences. The novelty of this approach lies in starting from the full multidimensional posterior distribution of nuclear matter parameters, consistent with a comprehensive set of static and dynamic nuclear structure observables. We construct unified EoSs for $npe\mu$ matter, where the inner crust of the NS is treated using an extended Thomas-Fermi method, providing for the first time a fully consistent Bayesian treatment of the correlation of bulk with surface as well as with spin-orbit and effective mass parameters. We then employ a standard Bayesian framework to identify those EoSs that satisfy astrophysical constraints from NS mass measurements, the tidal deformability from GW170817, and NICER mass-radius observations. We also examine NS observables, such as the crustal moment of inertia, which is crucial in understanding pulsar glitches. Compared to previous works, we observe an increase in both the NS surface thickness and the crustal moment of inertia.

We address the microscopic origin of the low-energy enhancement (LEE) in ${}^{50}\mathrm{V}$ with large-scale shell-model calculations to obtain $E1$ and $M1$ transitions within the same theoretical framework. The valence space spans the three major shells $sd, pf$, and $sdg$ and is treated with the SDPFSDG-MU interaction using the kshell code. With a $1\hslash \omega$ truncation, 3600 energy eigenstates and a basis of $7.02\times {10}^6$ positive- and $5.94\times {10}^8$ negative-parity states, the calculations yield nearly two million individual dipole transitions. The fourteen lowest experimental levels are reproduced within 0.30 MeV, the calculated total level density excellently reproduces Oslo-method data up to $E\approx 7.5$ MeV, and the calculated dipole gamma strength function follows the experimental shape—including the LEE—for the full gamma-energy range covered by the Oslo experiment. The LEE is shown to be entirely magnetic dipole in origin. Both spin and orbital parts of the $\widehat{M}1$ operator are required to reproduce the LEE, with constructive interference between the spin and orbital parts giving an extra enhancement to the LEE. Reduced one-body transition densities identify $0f_{7/2}\to 0f_{7/2}$ proton transitions as the principal driver of the LEE.

Most nuclei are deformed, and these deformations play an important role in various nuclear and astrophysical phenomena. Microscopic nuclear-mass models have been developed based on covariant density-functional theory to explore exotic nuclear properties. Among these, we adopt mass models based on the relativistic continuum Hartree-Bogoliubov theory (RCHB) with spherical symmetry and the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) with axial symmetry to study the effects of deformation on the abundances produced during the rapid neutron-capture process ($r$ process). Since the DRHBc mass table has so far been completed only for even-$Z$ nuclei, we first investigate whether a deep neural network (DNN) can be used to extend the DRHBc mass table by focusing on nuclear binding energies. To incorporate information about odd-odd and odd-even isotopes into the DNN, we also use binding energies from AME2020 as a training set, in addition to those from the DRHBc mass table for even-$Z$ nuclei. After generating an improved mass table through the DNN study, we conduct a sensitivity analysis of $r$-process abundances to deformation or mass variations using the ${\mathrm{RCHB}}^{★}$ and ${\mathrm{DRHBc}}^{★}$ mass tables, where $★$ indicates that the mass table is obtained from the DNN study. For the $r$-process sensitivity study, we consider magnetohydrodynamic jets, collapsar jets, and neutron-star mergers. Our findings indicate that $r$-process abundances can be sensitive to nuclear deformation, particularly within the mass range of $A=80–120$.

Fission fragment mass and total kinetic energy (TKE) distributions reported in [E. Vardaci et al., Phys. Rev. C 92, 034610 (2015)] for the reaction ${}^{32}\mathrm{S}{+}^{100}\mathrm{Mo}$ leading to ${}^{132}\mathrm{Ce}$ compound nucleus at the excitation energy $E_x=122\mathrm{MeV}$ are analyzed by means of an improved scission-point model that describes the shape of the compound nucleus at scission in terms of Cassini ovals. This study is motivated by a former comparison of the experimental fission data with the predictions of a dynamical model of fission, based on three-dimensional Langevin equations, that showed a significant disagreement with the measured TKE distribution. A broader set of nuclear shapes is accessible with Cassini ovals, in contrast to the more limited flexibility of the “Funny Hills” parametrization used in the dynamical code. For this reason, the present results show a clearer improvement in reproducing the experimental mass and TKE distributions compared to the dynamical model. Moreover, the present work highlights the need to consistently account for a nonequilibrium contribution, such as a deep-inelastic process, in both the mass and TKE distributions, for an estimated amount of $23.5\%$ of the total yield. In the present work, the potential energy surface at the moment of neck rupture (corresponding to the scission parameter $\alpha$ = 0.985) is computed as a function of the shape parameters ${\alpha }_1$, accounting for the mass asymmetry, and ${\alpha }_4$, accounting for the elongation at the scission point. Then a minimization on ${\alpha }_6$, which accounts for small oscillations around the nuclear shape, is performed at each point (${\alpha }_1, {\alpha }_4$). Furthermore, model calculations have been extended beyond the measured fragment mass asymmetry range to investigate the path towards the Businaro-Gallone transition.

I present a direct boundary matching method (DBMM) for solving nuclear scattering problems using Lagrange-Legendre basis functions. This approach belongs to the family of bound-state techniques for the continuum, reformulating scattering problems into a localized, square-integrable ($L^2$) representation. The key feature is the direct incorporation of the outgoing wave boundary condition into the last row of the matrix equation, eliminating the need for Bloch operators and two-step matching procedures required in traditional R-matrix methods. Unlike the complex scaling method that rotates coordinates into the complex plane, DBMM operates entirely in real coordinate space. The formalism is extended to coupled-channel problems, where the wave function decomposition naturally leads to an effective source potential that distinguishes between the entrance channel and other channels. Benchmark calculations for p $+ {}^{12}\mathrm{C}$ scattering demonstrate excellent agreement with the Numerov integration method.

The quark-meson coupling (QMC) model incorporates quark degrees of freedom into the relativistic mean-field (RMF) framework, distinguishing it from traditional quantum hadrodynamics (QHD), which treats nucleons as pointlike particles. In this work, we implement the QMC model within the DaeJeon Boltzmann-Uehling-Uhlenbeck (DJBUU) transport code to investigate its applicability to intermediate-energy heavy-ion collisions. We simulate ${}^{197}\mathrm{Au}+{}^{197}\mathrm{Au}$ collisions at a beam energy of $400A$ MeV using both QHD and QMC and find that the two approaches yield comparable results for bulk observables such as transverse and directed flow, with good agreement with experimental data. To further assess the model performance, we study pion production in neutron-rich (${}^{132}\mathrm{Sn}+{}^{124}\mathrm{Sn}$) and less neutron-rich (${}^{108}\mathrm{Sn}+{}^{112}\mathrm{Sn}$) systems at $270A$ MeV. In contrast to the QHD case, reproducing the observed pion yields and charge ratios within the QMC framework requires a slightly reduced density-dependent suppression in the in-medium $\mathrm{\Delta }$ production cross section. These results demonstrate that the QMC model can be effectively integrated into transport simulations.

Jet interactions with the color-deconfined quantum chromodynamics medium in relativistic heavy-ion collisions are conventionally assessed by measuring the modification of the distributions of jet observables with respect to their baselines in proton-proton collisions. Deep learning methods enable per-jet evaluation of these modifications, enhancing the use of jets as precision probes of the nuclear medium. In this work, we predict the jet-by-jet fractional energy loss $\chi$ for jets evolving through a quark-gluon plasma (QGP) medium using a linear Boltzmann transport model. To approximate realistic experimental conditions, we embed medium-modified jets in a thermal background and apply constituent subtraction for background removal. Two network architectures are studied: convolutional neural networks (CNNs) using jet images, and dynamic graph convolutional neural networks (DGCNNs) using particle clouds. We find that CNNs achieve accurate predictions for background-free jets but degrade in the presence of the QGP background and remain below the background-free baseline even after background subtraction. In contrast, DGCNNs applied to background-subtracted particle clouds maintain high accuracy across the entire $\chi$ range, demonstrating the advantage of point-cloud–based graph neural networks that exploit full jet structure under realistic conditions.

Predictions of the proton-directed flow $v_1$ in semicentral $\mathrm{Au}+\mathrm{Au}$ collisions in the energy range between 4.5 and 7.7 GeV are done. The calculations are performed within the model of three-fluid dynamics with crossover equation of state, which well reproduces the proton $v_1$ both below 4.5 GeV and above 7.7 GeV, as well as bulk observables in the energy range of interest. It is predicted that the proton flow evolves nonmonotonously. At the energy of 7.2 GeV it exhibits antiflow [i.e., negative slope of $v_1\left(y\right)$] in the midrapidity. At 7.7 GeV, the flow returns to the normal pattern in accordance with the STAR data. The midrapidity $v_1$-slope excitation functions within the first-order phase and crossover transitions to quark-gluon phase (QGP) turn out to be qualitatively similar, but the amplitude of the wiggle in the crossover scenario is much smaller than that in the strong first-order phase transition. Therefore, the change of sign followed by minimum at 7.2 GeV in the $v_1$-slope excitation function indicates onset of (weak phase or crossover) transition to QGP. The second change of the sign around 10 GeV results from interplay between incomplete baryon stopping and transverse expansion of the system.

The ${}^{92}\mathrm{Mo}(p,\gamma ){}^{93}\mathrm{Tc}$ cross section was measured at the University of Notre Dame Nuclear Science Laboratory in the energy range $E_{\mathrm{eff}}=1.45–4.29$ MeV. Data were collected using the High EffiCiency TOtal absorption spectrometeR (HECTOR) and analyzed using the $\gamma$-summing technique. Partial cross sections to the ground state and to the first excited state, as well as the total cross section, are reported. The measured cross section shows resonancelike structure at low energies and is about a factor of 2 lower than that predicted by non-smoker across the measured energy range. No Hauser-Feshbach model combination available within talys fully reproduces the cross section data. The reaction rate obtained in this work is up to a factor of 5 lower than that recommended by the reaclib database, indicating that the photodisintegration of ${}^{93}\mathrm{Tc}$ does not play a substantial role in the production of ${}^{92}\mathrm{Mo}$.

Within the relativistic point-coupling model in conjunction with the similarity renormalization group (SRG), we systematically investigate the correlations between relativistic symmetry and subshell evolution in nuclear systems. Guided by the concepts of pseudospin symmetry (PSS) and spin symmetry (SS), we study the formation of bubble-like structures in both new $N\left(Z\right)=14,16$ and traditional $N=82$ magic number isotones. By analyzing neutron/proton density profiles and the breaking behavior of PSS across the isotopic chain from neutron-rich oxygen (O) to neutron-deficient calcium (Ca), our model identifies all examined $N=14$ isotones as potential neutron bubble nuclei. For proton bubble-like candidates, ${}^{22}\mathrm{O}$ to ${}^{28}\mathrm{Si}$ (in $N=14$ isotones) and ${}^{28}\mathrm{Mg}$ to ${}^{30}\mathrm{Si}$ (in $N=16$ isotones) are proposed. In the light nuclei region, the emergence of semibubble structures is attributed to large pseudospin energy splitting, whereas the formation of bubble-like structures in $N=82$ isotones is unlikely due to small pseudospin energy splitting and the intervening $1h_{11/2}$ orbital between the $3s_{1/2}$ and $2d_{3/2}$ states. Through analytical decomposition of the Dirac Hamiltonian using SRG, we clarify the origins and breaking mechanisms of PSS and SS. A key distinction between light and heavy systems is revealed: in light systems, the spin-orbit term primarily determines the quality of PSS, while in all examined mass regions, SS is governed by spin-orbit interactions. Notably, the dominant role and variation of the spin-orbit term in determining PSS quality in light systems serves as a clear indicator for the emergence or suppression of bubble-like structures.

Macroscopic-microscopic models are a popular family of models used to accurately calculate various observables, such as masses or fission yields. In this article, we reexamine the well-known finite-range liquid-drop model using a new shape parametrization based on Fourier series. We present a new fitting protocol for the model to study statistical properties such as the correlation between parameters and their statistical uncertainties. We then use these results to propagate uncertainties on nuclear masses and fission barriers.

We study the flavor dependence of the chiral magnetic effect by analyzing two key charge-separation correlators used to characterize the charge separation effect: the conventional $\gamma$ correlator and the recently proposed $R_{{\psi }_2}$. Using A Multi-Phase Transport model with an initial-state centrality-dependent charge separation, we evaluate the sensitivity of these correlators to two-flavor ($u,d$) and three-flavor ($u,d,s$) quark scenarios. While both correlators exhibit modest flavor dependence in midcentral (30–50%) collisions, their discriminative power varies significantly with centrality and transverse momentum ($p_T$), limiting their utility disentangling the flavor-dependent scenarios. To overcome these limitations, we develop a neural network classifier trained on final-state hadronic observables (e.g., $d{N}_{\mathrm{ch}}/d\eta , p_T$ spectra). The model achieves $>90\%$ accuracy in flavor classification by leveraging multiobservable correlations, with $p_T$-differential features proving particularly discriminative. Crucially, by incorporating background contributions directly into the training data, our approach provides more reliable flavor estimates than correlator-only methods.