This paper compiles the model parameters and zero-temperature properties of an extensive collection of published theoretical nuclear interactions, including 255 nonrelativistic (Skyrme-like) forces, 270 relativistic mean field (RMF) and point-coupling (RMF-PC) forces, and 13 Gogny-like forces. This forms the most exhaustive tabulation of model parameters to date. The properties of uniform symmetric matter and pure neutron matter at the saturation density are determined. Symmetry properties found from the second-order term of a Taylor expansion in neutron excess are compared with the energy difference of pure neutron and symmetric nuclear matter at the saturation density. Selected liquid-droplet model parameters, including the surface tension and surface symmetry energy, are determined for semi-infinite surfaces. Theoretical liquid droplet model neutron skin thicknesses of the neutron-rich closed-shell nuclei ${}^{48}\mathrm{Ca}$ and ${}^{208}\mathrm{Pb}$ are compared with published theoretical Hartree-Fock and experimental results. A similar comparison is made between theoretical liquid-droplet and experimental values of dipole polarizabilities. In addition, radii, binding energies, moments of inertia and tidal deformabilities of $1.2{\mathrm{M}}_{\odot }, 1.4{\mathrm{M}}_{\odot }$ and $1.6{\mathrm{M}}_{\odot }$ neutron stars are computed. An extensive correlation analysis of bulk matter, nuclear structure, and low-mass neutron star properties is performed and compared with nuclear experiments and astrophysical observations.

We previously studied the inner crust and the pasta mantle of a neutron star within the fourth-order extended Thomas-Fermi (ETF) approach with consistent proton shell corrections added perturbatively via the Strutinsky integral (SI) theorem together with the contribution due to pairing. To speed up the computations and avoid numerical problems, we adopted parametrized nucleon density distributions. However, the errors incurred by the choice of the parametrization are expected to become more significant as the mean baryon number density is increased, especially in the pasta mantle where the differences in the energy per nucleon of the different phases are very small, typically a few keV. To improve the description of these exotic structures, we discuss the important features that a nuclear profile should fulfill and introduce two new parametrizations. Performing calculations using the BSk24 functional, we find that these parametrizations lead to lower ETF energy solutions for all pasta phases than the parametrization we adopted before and more accurately reproduce the exact equilibrium nucleon density distributions obtained from unconstrained variational calculations. Within the ETFSI method, all parametrizations predict the same composition in the region with quasispherical clusters. However, the two new parametrizations lead to a different mantle structure at mean baryon densities above about $0.07{\mathrm{fm}}^{-3}$, at which point lasagna is energetically favored. Interestingly, spherical clusters reappear in the pasta region. The inverted pasta phases such as bucatini and Swiss cheese are still found in the densest region above the core in all cases.

Background: To describe shape fluctuations associated with large-amplitude collective motion in the quadrupole degrees of freedom, the five-dimensional collective Hamiltonian (5DCH) has been widely used. The inertial functions in the 5DCH are microscopically calculated with the energy density functional (EDF) theory employing the cranking formula. However, since the cranking formula ignores dynamical residual effects, it is known to fail to reproduce the correct inertial functions, for instance, the total mass for the translational motion.

Purpose: We aim to resolve problems of the insufficient description of the inertial functions in the 5DCH. We provide a practical method to include the dynamical residual effects in the inertial functions that depend on the quadrupole deformation parameters $\beta$ and $\gamma$.

Methods: We use the local quasiparticle random-phase approximation (LQRPA) based on the constrained Hartree-Fock-Bogoliubov states in the $\beta \text{−}\gamma$ plane with the Skyrme EDF. The finite-amplitude method is used for efficient computations of the LQRPA.

Results: The inertial functions evaluated with the LQRPA significantly increase from the ones with the cranking formula due to the dynamical residual effects. This increase also shows a strong $\beta \text{−}\gamma$ dependence. We show an application of the present method to a transitional nucleus ${}^{110}\mathrm{Pd}$. The low-lying spectra are well reproduced with the LQRPA inertial functions.

Conclusions: We clarify the importance of the dynamical residual effects in the inertial functions of the 5DCH for the description of the low-lying spectra. The 5DCH with the improved inertial functions provides a reliable and efficient description of low-lying spectra in nuclei associated with the quadrupole shape fluctuation.

A collision between two atomic nuclei accelerated at a speed close to that of light creates a dense system of quarks and gluons. Interactions among them are so strong that they behave collectively like a droplet of fluid of ten-femtometer size, which expands into the vacuum and eventually fragments into thousands of particles. We report a new manifestation of thermalization in recent data from the Large Hadron Collider. Our analysis is based on results from the ATLAS Collaboration, which has measured the variance of the momentum per particle across $\text{Pb}+\text{Pb}$ collision events with the same particle multiplicity. This variance decreases steeply over a narrow multiplicity range corresponding to central collisions. We provide a simple explanation of this newly observed phenomenon: For a given multiplicity, the momentum per particle increases with increasing impact parameter. Since a larger impact parameter goes along with a smaller collision volume, this in turn implies that the momentum per particle increases as a function of density, which is a generic consequence of thermalization. Our analysis provides the first direct evidence of this phenomenon at the femtoscale.

The ${}^{10}\mathrm{C}+\alpha$ elastic cross section was measured to investigate the structure of the proton-rich ${}^{14}\mathrm{O}$ nucleus. A radioactive beam of ${}^{10}\mathrm{C}$ was produced at the RI beam separator CRIB using the ${}^{10}\mathrm{B}(p,n){}^{10}\mathrm{C}$ reaction with a ${}^{10}\mathrm{B}$ beam energy of 6.99 MeV/nucleon. A complex resonant structure is observed in ${}^{14}\mathrm{O}$ in the excitation energy region around 13–18 MeV, improving significantly our knowledge on the structure of this nucleus. An $R$-matrix analysis was performed to determine the properties of resonances. $\alpha$ clustering structure is observed for $J=0^{+}$ and $J=2^{+}$ at 13.44 and 14.88 MeV, respectively. These results are compared with the $\alpha$ clustering structure reported in the mirror nucleus ${}^{14}\mathrm{C}$.

Proton spectra and double differential cross sections were measured from ${}^7\mathrm{Li}$-induced reactions on ${}^{63,65}\mathrm{Cu}$ with a 15.5 MeV lithium beam. Protons were measured at four angles: 37, 52, 97, and 142 degrees in the laboratory frame. The spectra measured at 97 and 142 degrees were used to test level density models for ${}^{69,71}\mathrm{Ga}$ nuclei populated by protons. Also, the level density excitation energy functions were extracted and compared directly with model calculations and with previous results on level densities for near mass nuclei ${}^{74,76}\mathrm{Ge}$. It was found that the level density for ${}^{69}\mathrm{Ga}$ is consistent with the prediction of the back-shifted Fermi-gas model, while the level density for ${}^{71}\mathrm{Ga}$ is consistent with the ones for ${}^{74,76}\mathrm{Ge}$, which all are systematically lower than this model predicts. The models based on the Gilbert and Cameron approach and microscopic model are not supported by experimental data.

There is a major mismatch between the charged-pion yields in $\mathrm{Au}+\mathrm{Au}$ collisions at low energies calculated by various transport models and the experimental measured values from the HADES Collaboration. In this work, reasonable improvements on the equation of state, in-medium modification of cross sections, and the influence of the nuclear potential for $\mathrm{\Delta }$ resonances will be investigated in the framework of the GiBUU transport model. As a result, we demonstrate that theoretical calculations can indeed describe the charged-pion yields measured by HADES for $\mathrm{Au}+\mathrm{Au}$ collisions rather well, but that a mismatch then remains between calculations and data for the yields of neutral pions extracted from dileptons within the same experiment.

Analytical solutions to the microscopic Boltzmann equation are useful in testing the applicability and accuracy of macroscopic hydrodynamic theory. In this work, we present exact solutions of the relativistic Boltzmann equation, based on a new family of exact solutions of the relativistic ideal hydrodynamic equations [S. Shi, S. Jeon, and C. Gale, Phys. Rev. C 105, L021902 (2022)]. To the best of our knowledge, this is the first exact solution that allows longitudinal expansion with broken boost invariance.

We study the relation between measured high-$x_B$, high-$Q^2$, helium-3 to tritium, $(e,e^{\prime })$ inclusive-scattering cross-section ratios and the relative abundance of high-momentum neutron-proton ($np$) and proton-proton ($pp$) short-range correlated nucleon pairs in three-body ($A=3$) nuclei. Analysis of these data using a simple pair-counting cross-section model suggested a much smaller $np/pp$ ratio than previously measured in heavier nuclei, questioning our understanding of $A=3$ nuclei and, by extension, all other nuclei. Here, we examine this finding using spectral-function-based cross-section calculations, with both an ab initio $A=3$ spectral function and effective generalized contact formalism spectral functions using different nucleon-nucleon interaction models. The ab initio calculation agrees with the data, showing good understanding of the structure of $A=3$ nuclei. An 8% uncertainty on the simple pair-counting model, as implied by the difference between it and the ab initio calculation, gives a factor of 5 uncertainty in the extracted $np/pp$ ratio. Thus we see no evidence for the claimed “unexpected structure in the high-momentum wave function for hydrogen-3 and helium-3.”

Developments in the description of the masses of atomic nuclei have led to various nuclear mass models that provide predictions for masses across the whole chart of nuclides. These mass models play an important role in understanding the synthesis of heavy elements in the rapid neutron capture ($r$) process. However, it is still a challenging task to estimate the size of uncertainty associated with the predictions of each mass model. In this work, a method called ensemble Bayesian model averaging (EBMA) is introduced to quantify the uncertainty of one-neutron separation energies ($S_{1n}$) which are directly relevant in the calculations of $r$-process observables. This Bayesian method provides a natural way to perform model averaging, selection, and uncertainty quantification, by combining the mass models as a mixture of normal distributions whose parameters are optimized against the experimental data, employing the Markov chain Monte Carlo method using the no-u-turn sampler. The EBMA model optimized with all the experimental $S_{1n}$ from the AME2003 nuclides are shown to provide reliable uncertainty estimates when tested with the new data in the AME2020.

The yrast and nonyrast states of ${}^{126}\mathrm{Te}$ were populated in a fusion-evaporation reaction using a target of ${}^{124}\mathrm{Sn}$ and $\alpha$ beam at 31 MeV energy. All the $\gamma \text{−}\gamma$ coincidences were recorded using the Indian National Gamma Array at the Variable Energy Cyclotron Centre, India, and processed by a digital data-acquisition system. The level scheme was enriched with the addition of 65 new transitions and the identification of five new structures. Spin and parity assignments were made and the subsequent results were interpreted in the framework of the nuclear shell model using the large-scale shell-model code antoine.

The multinucleon transfer reactions ${}^{78,82,86}\mathrm{Kr}+{}^{208}\mathrm{Pb}$ at near-barrier energy are investigated by the improved quantum molecular dynamics model with the subsequent decay model gemini. The isotopic distributions of the products in the ${}^{136}\mathrm{Xe}+{}^{208}\mathrm{Pb}$ reaction at $E_{\text{c.m.}}=450$ MeV are calculated and compared with the experimental data. The influence of isospin equilibration of the primary products in the ${}^{78,82,86}\mathrm{Kr}+{}^{208}\mathrm{Pb}$ reactions are investigated. It suggests that the projectile ${}^{86}\mathrm{Kr}$ is favorable to the yields of neutron-rich nuclei. The total kinetic energy mass distributions and the evolution of the neck in collisions of ${}^{86}\mathrm{Kr}+{}^{208}\mathrm{Pb}$ at incident energies of $E_{\text{lab}}=5.40$, 6.40, and 7.40 MeV/nucleon are calculated. By analyzing the incident energy effect on the mass distributions and isotopic distributions of products in the reaction of ${}^{86}\mathrm{Kr}+{}^{208}\mathrm{Pb}$, we find that 6.40 MeV/nucleon is more suitable for producing neutron-rich isotopes near $N=126$.

A model for hot-fusion reactions leading to the synthesis of superheavy nuclei is discussed. The values of the hot-fusion cross sections obtained in the model agree with the available experimental data. The hot-fusion cross sections are found for two different models of the fission barrier heights of superheavy nuclei. The calculations of the cross sections for the various hot-fusion reactions leading to the 119 and 120 elements are presented. Simple expressions useful for qualitative analysis of the cross section for forming superheavy nuclei are obtained. It is shown that the superheavy nuclei production cross section is proportional to the transmission coefficient of the capture barrier, realization probability of the $xn$-evaporation channel, and exponentially depends on the quasielastic barrier, fusion reaction $Q$ value, compound nucleus formation barrier, neutron separation energies, and fission barrier heights.

We present a new three-dimensional resolved model for the initial state of ultrarelativistic heavy-ion collisions, based on the $k_{\perp }$-factorized color glass condensate (CGC) hybrid approach. The McDipper framework responds to the need for a rapidity-resolved initial-state Monte Carlo event generator which can deposit the relevant conserved charges (energy, charge, and baryon densities) both in the midrapidity and forward (backward) regions of the collision. This event-by-event generator computes the gluon and (anti-) quark phase-space densities using the IP-Sat model, from where the relevant conserved charges can be computed directly. In the present work we have included the leading-order contributions to the light flavor parton densities. As a feature, the model can be systematically improved in the future by adding next-to-leading-order calculations (in the CGC hybrid framework) and extending to lower energies by including subeikonal corrections to the channels included. We present relevant observables, such as the eccentricities and flow decorrelation, as tests of this new approach.

The back-shifted Fermi gas model is widely employed for calculating nuclear level density (NLD) as it can effectively reproduce experimental data by adjusting parameters. However, selecting parameters for nuclei lacking experimental data poses a challenge. In this study, a feedforward neural network (FNN) was utilized to learn the level density parameters at neutron separation energy $a\left(S_n\right)$ and the energy shift $\Delta$ for 289 nuclei. Simultaneously, parameters for nearly 3000 nuclei are provided through the FNN. Using these parameters, calculations were performed for neutron resonance spacing in $s$ and $p$ waves, cumulative number of levels, and NLD. The FNN results were also compared with the calculated outcomes of the parameters from fitting experimental data (local parameters) and those obtained from systematic studies (global parameters), as well as the experimental data. The results indicate that parameters from the FNN achieve performance comparable to local parameters in reproducing experimental data. Moreover, for extrapolated nuclei, parameters from the FNN still offer a robust description of experimental data.

The stability of nuclear isomers reflects a complex interplay of quantum-mechanical factors, influenced by the nuclear structure and the single-particle arrangement of nucleons within the nucleus. Here, we trace the factors behind the abundance and persistence of 1342 isomers over the trans-tin region of the nuclear chart from Sn to Tl, providing insight into the role of single-particle structure in controlling their stability and $\alpha$ decays. We found that nucleons originally belonging, or transferred, to the $\pi ,\nu 1h_{11/2}{}^{-}$ and $\nu 1i_{13/2}^{}+$ shell-model orbitals are directly connected to a substantial fraction of the observed isomers in this region, especially the more copious and more stable among them in addition to those of very high spin. They contribute either solely as odd valence nucleons or via a pure character of fully aligned configurations of a multiple of them, or with coupling to other valence nucleons, in addition to possible phonon coupling to lower spin states. A similar role is played by the $\pi 1g^{-1}{}_{7/2}^{+}$ ($\pi 3s_{1/2}^{+}$) proton hole for the copious and more stable Ta (Tl) isomers, by two protons reside outside the closed core of $Z_0=50$ in Te, by one (two) vacancies to the shell closure of $N_0=82$ for the isomers of $N=81$ (80), by valence $\nu 1h_{9/2}{}^{-}$ neutrons (hole) for $N=107$, and by a single lacked $\nu 3s_{1/2}^{+}$ neutron for $N=79$. The extracted $\alpha$-preformation probability is indicated to increase in isomers relative to their authentic ground states, when they release less energy. As in ground states, the stability of the isomeric states effectively increases with increasing the presupposed transfer of angular momentum, and, if the decay implicates a change in parity; lower value of the preformation probability is indicated in both cases. This clarifies the observed greater stability against $\alpha$ decay of many isomers of high spin relative to their ground states.

The semiexclusive averaged reduced cross sections for (anti)neutrino charged current quasielastic scattering on carbon, oxygen, and argon are analyzed within the relativistic distorted wave impulse approximation. One finds that these cross sections as functions of missing nucleon energy are similar to those of electron scattering and are in agreement with electron scattering data for the three nuclei. The difference between the electron and neutrino cross sections can be attributed to Coulomb distortion on the electron wave function. The averaged reduced cross sections depend slowly upon incoming lepton energy. The approach presented in this paper provides novel constraints on nuclear models of quasielastic neutrino-nucleus scattering and can be easily applied to test spectral functions and final state interactions employed in neutrino event generators.

Background: Nuclei around ${}^{20}\mathrm{Ne}$ exhibit an interplay of different excitations caused by different aspects of nuclear structure, including single-particle and multiparticle configurations and collective rotations. One-nucleon transfer reactions selectively probe single-particle structures in these nuclei. These nuclei are also important to astrophysics, with a number of important reactions proceeding through this mass region.

Purpose: Energy levels approaching the $\alpha$-particle threshold in ${}^{21}\mathrm{Ne}$ are of importance to nuclear structure. The ${}^{20}\mathrm{Ne}(d,p){}^{21}\mathrm{Ne}$ reaction was measured and the corresponding spectroscopic nuclear information was extracted.

Method: States in ${}^{21}\mathrm{Ne}$ were populated using the ${}^{20}\mathrm{Ne}(d,p){}^{21}\mathrm{Ne}$ reaction in forward kinematics. Protons were identified in the Triangle Universities Nuclear Laboratory (TUNL) Enge split-pole spectrograph and angular distributions were extracted. Spin-party assignments were made and neutron partial widths were determined based on distorted-wave Born approximation (DWBA) analysis.

Results: Several new energy levels were observed at energies of 7176, 7235, 7250, and 7337 keV, and spin-parities are reported which generally agree with previous results where literature was available. Spin and parity assignments are reported for several energy levels along with estimated neutron widths for those states above the neutron threshold ($S_n=6761\mathrm{keV}$).

Conclusions: Results from this study are placed in context with a review of the available literature on all known states in this energy region of ${}^{21}\mathrm{Ne}$.

We present an extensive study of hexadecapole correlations in the rare-earth region near $N=90$ and the effects these correlations have on various nuclear properties, such as the low-energy spectra, as well as quadrupole, hexadecapole, and monopole transition strengths. In order to examine hexadecapole correlations, we employ a mapped $sdg$ interacting boson model, with parameters derived from a self-consistent mean-field calculations with a relativistic energy density functional. We apply this model to even-even isotopes of Nd, Sm, Gd, Dy, and Er ($Z=60–68$) with neutron numbers $N=84–96$. The obtained results show a good agreement with the experiment. By comparing the results with the ones obtained from a simpler mapped $sd$ interacting boson model, we show that the inclusion of the hexadecapole degree of freedom via the $g$ boson is necessary to improve the results of the $J^{\pi }\ge 6^{+}$ yrast energies in the nuclei with $N=84$ and 86, being near the neutron shell closure. The $sdg$ interacting boson model increases the quadrupole transition strengths between yrast states in the $N=90$ and 92 well deformed nuclei, which is in good agreement with the experiment for most of those isotopes. The presence of $g$ bosons does have an important effect on hexadecapole transition strengths, although experimental data for such transitions are limited. The obtained monopole transition strengths do not differ significantly from the ones obtained from the simpler $sd$ model.

Nuclear $(n,2n)$ reaction cross sections are studied based on the Bayesian neural network (BNN) approach. Three physical quantities besides the proton and neutron numbers are proposed to improve the performance of the BNN approach. These three physical quantities are the incident neutron energy with respect to the reaction threshold, the physical quantity related to the odd-even effect, and the theoretical $(n,2n)$ reaction cross section, and they are included as the inputs to the neural network. The BNN approach has better performance in the description of the $(n,2n)$ reaction cross sections than the theoretical library TENDL-2021 calculated by the talys code based on the Hauser-Feshbach statistical model, especially for heavy nuclei. The root-mean-square deviation of the BNN approach with respect to the evaluation data is reduced to 0.10 barns compared to 0.25 barns of TENDL-2021. The extrapolation ability of the BNN approach is verified with the $(n,2n)$ cross section data that are not used to train the neural network. Furthermore, it is found that the BNN approach still well describes the trend of the $(n,2n)$ cross sections with the incident neutron energy predicted by TENDL-2021 even when extrapolated to the unknown region.