To the single folding potentials (SFPs) for the nucleon-nucleus ($N\text{−}A$) elastic scatterings, local approximations (LAs) have customarily been applied. The LA discussed by Brieva and Rook has been well known, which only needs the density profile as the structure information of the target nucleus. By applying the M3Y-P6 interaction both to the target wave functions and the real part of SFP, supplemented with the Koning-Delaroche phenomenological imaginary potential, the precision of the Brieva-Rook LA on the SFP is investigated for the proton-nucleus elastic scatterings at ${\epsilon }_p=16–80\mathrm{MeV}$ incident energies. The analyzing powers as well as the differential cross sections are in reasonable agreement with the available data. The precision of the LA for the central and LS channels is distinctly examined. Although the LA works well at small angles (${\theta }_{\mathrm{c}.\mathrm{m}.}\lesssim {30}^{\circ }$), it gives rise to sizable deviation from the results of the nonlocal SFP (i.e., without the LA) at larger angles. The results of the nonlocal SFP are always in better agreement with the data. The LA for the LS channel influences the differential cross sections, and the LA for the central channel does the spin observables. It is found that the precision of the LA well correlates to the momentum transfer $q$, and the discrepancy becomes sizable at $q\gtrsim 1.5{\mathrm{fm}}^{-1}$. The LA is also examined for a halo nucleus, by taking ${}^{86}\mathrm{Ni}$ as an example. The precision is slightly worse than in stable nuclei. Difference from the prediction of the empirical potential in the observables of the $p\text{−}{}^{86}\mathrm{Ni}$ scattering is discussed.

The breaking of translational symmetry in the inner crust of a neutron star leads to the depletion of the neutron superfluid reservoir similarly to cold atomic condensates in optical lattices and in supersolids. This effect is studied in the general framework of the self-consistent time-dependent Hartree-Fock-Bogoliubov (HFB) theory, treating the crust as a perfect crystal. The superfluid fraction is derived in the Bardeen-Cooper-Schrieffer approximation for superfluid velocities much smaller than Landau's critical velocity within the linear-response theory. The different assumptions made in previous studies are clarified. Fully three-dimensional band-structure calculations of superfluid neutrons in a body-centered cubic lattice are carried out. Although the formation of Cooper pairs is essential for the occurrence of superfluidity, the superfluid fraction is found to be insensitive to the pairing gap, as in uniform neutron matter. In the intermediate region of the inner crust at the average baryon number density $0.03{\mathrm{fm}}^{-3}$, only 8% of the free neutrons are found to participate to the superflow. Such very low superfluid fraction challenges the classical interpretation of pulsar frequency glitches and calls for more systematic calculations within the full HFB approach.

We discuss new spin observables presently accessible to measurement in the proton-deuteron ($\mathit{pd}$) system, namely polarization transfer coefficients from the doubly spin-polarized initial state to the outgoing nucleon in the elastic nucleon-deuteron ($\mathit{Nd}$) scattering and in the nucleon-induced deuteron breakup reactions. The sensitivity of these observables to three-nucleon force ($3N\mathrm{F}$) effects is investigated and compared to sensitivities of the constituent standard single polarization transfer coefficients in the neutron-deuteron ($\mathit{nd}$) system. $K_{y,y}^{y^{\prime }}$ in elastic $\mathit{nd}$ scattering, for which large $3N\mathrm{F}$ effects, up to 40%, have been found at higher energies, seems the most promising observable to measure.

We present a systematic study of the low-lying positive and negative parity states of the ${}^{216–228}\mathrm{Ra}$ isotopic chain in the context of the $spdf$ interacting boson model $(spdf\text{−}IBM\text{−}1)$. The goal is to reproduce the experimental data for the level energies and the electromagnetic transition rates between them of these isotopes using a reduced set of Hamiltonian parameters. To do this task, a minimization routine based in minuit was used. Also the potential energy surfaces were obtained and their minima show a transition from spherical to deformed shapes when the neutron number increases throughout the isotopic chain.

Nuclear mass is fundamental in both nuclear physics and astrophysics. Different theoretical mass models have been proposed based on distinct assumptions, leading to varied mass predictions. In this work, we employ a Gaussian process regression (GPR) machine learning (ML) model to systematically investigate the prediction differences among four theoretical mass models, namely, $\mathrm{Weizs}\ddot{a}\text{cker-Skyrme–type}$, finite-range droplet model–type, covariant density functional theory–type, and Bethe-$\mathrm{Weizs}\ddot{a}\text{cker–type}$ models. We use three feature sets with different numbers of features to study their impacts on the accuracy of the GPR model. The fact is confirmed that the accuracy can be improved by increasing the number of features. With the optimal feature set, the GPR model achieves an overall accuracy of approximately 0.2 MeV for these four mass evaluations. Besides, the prediction differences among these mass models are also systematically investigated by using interpretable ML techniques, which can provide insights into the underlying physical factors responsible for their prediction differences as well as more comprehensions on the nuclear mass evaluations.

This paper presents a measurement of jet-track correlations in photon-jet events, using 1.72 ${\text{nb}}^{-1}$ of $\mathrm{Pb}+\mathrm{Pb}$ data at $\sqrt{s_{NN}}=5.02\mathrm{TeV}$ recorded with the ATLAS detector at the LHC. Events with energetic photon-jet pairs are selected, where the photon and jet are approximately back-to-back in azimuth. The angular correlation between jets and charged-particle tracks with transverse momentum ($p_{\text{T}}$) in the range 0.5–2.0 GeV in the hemisphere opposite to the jet, $\left|\mathrm{\Delta }\varphi \text{(jet,track)}\right|>\pi /2$, is measured as a function of their relative pseudorapidity difference, $\left|\mathrm{\Delta }\eta \text{(jet,track)}\right|$. In central $\mathrm{Pb}+\mathrm{Pb}$ collisions, these correlations are predicted to be sensitive to the diffusion wake in the quark-gluon plasma resulting from the lost energy of high-$p_{\text{T}}$ partons traversing the plasma, with a characteristic modification as a function of $\left|\mathrm{\Delta }\eta \text{(jet,track)}\right|$. The correlations are examined with different selections on the jet-to-photon $p_{\text{T}}$ ratio to select events with different degrees of energy loss. No diffusion wake signal is observed within the current sensitivity and upper limits at 95% confidence level on the diffusion wake amplitude are reported.

We present an analytically solvable model based on the blast-wave picture of heavy-ion collisions with flow-momentum correspondence. It can describe the key features of spin polarization in heavy-ion collisions. With the analytical solution, we can clearly show that the spin polarization with respect to the reaction plane is driven by the directed flow, while the spin polarization along the beam direction is driven by the ellipticity in flow and in transverse emission area. There is a symmetry by interchanging $sinh\rho$ and $cosh\rho$ ($\rho$ is the transverse rapidity) between collective flow contributions to the spin polarization from the vorticity and from the shear stress tensor due to the flow-momentum correspondence. The solution can be improved systematically by perturbation method.

A new isomeric $\left(4^{-}\right)$ state at 285.5(32) keV in ${}^{162}\mathrm{Tb}$ was reported by Orford et al. [Phys. Rev. C 102, 011303(R) (2020)] based on a Penning-trap mass measurement. Here, we show that this result is not compatible with existing experimental data. The state identified as ${}^{162}\mathrm{Tb}^m$ with a mass-excess value of $-65593.9\left(25\right)$ keV is actually the $1^{-}$ ground state. The state identified as the ground state of ${}^{162}\mathrm{Tb}$ is most likely a molecular contaminant with the same mass-over-charge ratio.

Earlier studies of spontaneous fission of heavy actinides found that the fission-fragment mass distribution suddenly changes from predominantly asymmetric to symmetric, when the mass number of the fissioning nucleus becomes larger than $A_{\mathrm{c}}=257$. We have measured for the first time fission-fragment mass and total-kinetic-energy (TKE) distributions of the excited compound nucleus ${}^{258}{\mathrm{Md}}^{*}$ ($Z=101)$, populated in the reaction ${}^4\mathrm{He}+{}^{254}\mathrm{Es}$, using the rare radioactive target isotope ${}^{254}\mathrm{Es}$ with a short half-life, $T_{1/2}=275.7\mathrm{d}$. The fission of ${}^{258}{\mathrm{Md}}^{*}$ can be interpreted as involving three fission modes: one mass-asymmetric and two mass-symmetric fission modes, the latter two are manifested by different TKE values. In this assumption, symmetric and asymmetric fission modes have nearly similar yields at the excitation energy of 15.0 MeV. The spectrum of 18.0 MeV can be explained as due to the increase of asymmetric fission mode.

In an intermediate-momentum regime where mass effects are significant, heavy-quark suppression and anisotropic flow are computed to investigate the transition between the collisional and radiative energy losses. Based on the collision kernel for diffusion, elastic scattering and semicollinear gluon bremsstrahlung can be consistently incorporated into a Boltzmann equation that involves the heavy-quark diffusion coefficient. Using the running coupling constant and the diffusion coefficient constrained by lattice QCD data, the collisional and radiative energy-loss contributions to the $R_{AA}$ and $v_2$ are studied in hydrodynamically expanding thermal media. The evolution of the observables, the bulk flow effect, and the dependence on mass and centrality are discussed in noncentral heavy-ion collisions.

We compute the neutron-neutron relative-energy distribution of the triton following the hard knockout of the proton in pionless effective field theory (EFT). This distribution can be used to study universality as well as to obtain information on the neutron-neutron interaction. In particular, one can infer the scattering length from fitting theory predictions for the shape of the distribution to experimental data. To obtain the distribution for the triton, we first solve the ground-state three-body problem using momentum-space Faddeev equations. Next, we include the neutron-neutron final-state interaction by applying the corresponding Møller operator to the ground state. We present leading-order and next-to-leading order (NLO) pionless effective field theory results with quantified uncertainties. At NLO, we include the effective ranges semi-perturbatively. We conclude that pionless EFT works reliably as expected and that the neutron-neutron distribution of the triton shows a significant sensitivity to the scattering length.

Improved neutron inelastic scattering cross sections have repeatedly been identified as a top priority nuclear data need, important for basic science and a range of applications in nuclear energy, stockpile stewardship, and proliferation detection. For the ${}^{12}\mathrm{C}$($n,n^{\prime }\gamma$) reaction in particular, recent measurements have unveiled some structural discrepancies, demonstrating incongruities among themselves and in relation to the ENDF/B-VIII.0 nuclear data evaluation. To help resolve these disagreements, a measurement was performed at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory using a broad-spectrum neutron beam and a 99.8% pure natural carbon target. The Gamma Energy Neutron Energy Spectrometer for Inelastic Scattering (GENESIS) was employed to measure energy-differential $\gamma$-ray emission spectra as a function of incident neutron energy in the energy range of 5.5 to 16.7 MeV. The ${}^{12}\mathrm{C}$ partial $\gamma$-ray cross sections were extracted at ${63}^{\circ }, 122.5^{\circ }$, and ${150}^{\circ }$ with respect to the incoming neutron beam and integrated using angular distribution data available in the literature. The data show agreement with a recent literature measurement and evaluation from 11 to 15 MeV, but indicate a larger cross section for incident neutron energies between 5.5 and 8.5 MeV. The measured relative angular distributions are also reported and were found to agree with evaluation.

We present bhac-qgp, a new numerical code to simulate the evolution of matter created in heavy-ion collisions in the presence of electromagnetic fields. It is derived from the Black Hole Accretion Code ( bhac), which has been designed to model astrophysical processes in a general-relativistic magnetohydrodynamical description. As the original Black Hole Accretion Code, bhac-qgp benefits from the use of adaptive mesh refinement, which allows us to dynamically adjust the resolution where necessary and makes use of time-dependent Milne coordinates and the ultrarelativistic equation of state, $P=e/3$. We demonstrate that bhac-qgp accurately passes a number of systematic and rigorous tests.

We present bhac-qgp, a numerical code to simulate the evolution of matter created in heavy-ion collisions. bhac-qgp is based on the Black Hole Accretion Code ( bhac), which has been designed to model astrophysical processes through the solution of the equations of general-relativistic magnetohydrodynamics. Like the mother code, bhac-qgp uses adaptive mesh refinement, which allows for a dynamic adjustment of the resolution in regions of the computational domain where a particularly high accuracy is needed. We here discuss a number of applications of bhac-qgp to Au-Au collisions at the BNL Relativistic Heavy-Ion Collider energies and show that the code is able to reproduce results of other simulations of these scenarios, but with much higher accuracy.

Background: Thermal fission rates have been calculated with various methods, such as Bohr-Wheeler theory, Kramers's formula, stochastic dynamics, and the Fokker-Planck equation (FPE). How to reasonably calculate fission rates is still a challenging subject.

Purpose: The FPE provides a powerful statistical model to describe nuclear fission. However, it is very difficult to solve with general numerical methods. We propose an algorithm with a neural network method to actually and accurately solve the FPE and, therefore, to calculate fission rates.

Methods: The proposed algorithm is used to obtain the probability distributions of the FPE. Fission rates and half-lives are calculated with the resultant probability distributions.

Results: Plausible predictions of fission half-lives match the experiment data well. The thermal fission rates and fission times are also consistent with various microscopic calculation results.

Conclusions: The results show that the FPE can be solved reliably and feasibly with our proposed algorithm with a reasonable accuracy. This algorithm can be used to analyze various transport problems.

Spontaneous neutron emission has been observed in many neutron-rich nuclei beyond the neutron drip line with the development of experimental nuclear physics. Compared with proton emission, $\alpha$ decay, and heavy cluster radioactivity, neutron emission has the same mechanism, namely quantum tunneling, but the research on neutron emission is still at its beginning. Our purpose is to extend the previous theoretical model of charged particle emission to neutron emission, especially the time evolution. In this work, the Woods-Saxon potential and spin-orbit interaction are used to construct the daughter-neutron potential. To calculate the half-life, as a dynamic simulation, TDSE (time-dependent Schrödinger equation) approach is employed to research the decay process in detail for some neutron emitters, and its results are compared with experiments and the Wentzel-Kramers-Brillouin (WKB) approximation, a conventional method of particle emission, verifying the stability of our model, despite relatively large or small half-lives or the emitters in the island of inversion. Particularly, we also theoretically calculate the extremely fast neutron radioactivity occurring in the recently discovered new nuclide ${}^{30}\mathrm{F}$ [Phys. Rev. Lett. 133, 082501 (2024)], and obtain results consistent with experiments. We also observe some new phenomena and propose a tentative conjecture to explain them, which is difficult to find using traditional methods. It is expected that this work can be a helpful reference for future studies of neutron-rich nuclei.

Pairing plays a crucial role in the microscopic description of nuclear fission. Microscopic methods provide access to three quantities related to pairing, namely, the pairing gap $\left(\mathrm{\Delta }\right)$, the particle number fluctuations $\left(\mathrm{\Delta }{\widehat{N}}^2\right)$, and the quenching factor of the pairing strength. The aim of this work is to analyze the impact of each of these quantities on the mean-field description of the fission process, including collective inertias.

The masses of the ground and isomeric states in ${}^{124,125}\mathrm{Ag}$ have been measured using the phase-imaging ion-cyclotron-resonance technique at the JYFLTRAP double Penning trap mass spectrometer. The ground states of ${}^{124}\mathrm{Ag}$ and ${}^{125}\mathrm{Ag}$ were found to be 30(250) keV and 250(430) keV less bound but 36 and 110 times more precise than in the Atomic Mass Evaluation 2020, respectively. The excitation energy of ${}^{124}\mathrm{Ag}^m$, $E_x=188.2\left(25\right)$ keV, was determined for the first time. The new precise mass values have been utilized to study the evolution of nuclear structure via two-neutron separation energies. The impact on the astrophysical rapid neutron capture process has been investigated via neutron-capture reaction rate calculations. The precision measurements indicate a more linear trend in two-neutron separation energies and reduce the mass-related uncertainties for the neutron-capture rate of ${}^{124}\mathrm{Ag}(n,\gamma ){}^{125}\mathrm{Ag}$ by a factor of around 100. The new mass values also improve the mass of ${}^{123}\mathrm{Pd}$, previously measured using ${}^{124}\mathrm{Ag}$ as a reference.

Coexistent phase of kaon condensates and hyperons [$(Y+K)$ phase] in beta equilibrium with electrons and muons is investigated as a possible form of dense hadronic phase with multistrangeness. The effective chiral Lagrangian for kaon-baryon and kaon-kaon interactions is utilized within the chiral symmetry approach in combination with the interaction model between baryons. For the baryon-baryon interactions, one adopts the minimal relativistic mean-field theory with exchange of scalar mesons $(\sigma ,$ ${\sigma }^{*})$ and vector mesons $(\omega ,$ $\rho ,$ $\varphi )$ between baryons without including the nonlinear self-interacting meson-field terms. In addition, the universal three-baryon repulsion and the phenomenological three-nucleon attraction are introduced as density-dependent effective two-body potentials. The repulsive effects leading to a stiff equation of state at high densities consist of both the two-baryon repulsion via the vector-meson exchange and the universal three-baryon repulsion. Interplay of kaon condensates with hyperons through chiral dynamics in dense matter is clarified, and the resulting onset mechanisms of kaon condensation in hyperon-mixed matter and the equation of state with the ($Y+K$) phase and characteristic features of the system are presented. It is shown that the slope $L$ of the symmetry energy controls the two-baryon repulsion beyond the saturation density and the resulting stiffness of the equation of state. The stiffness of the equation of state in turn controls the admixture of hyperons and the onset and development of kaon condensates as a result of competing effects between kaon condensates and hyperons. The equation of state with the ($Y+K$) phase becomes stiff enough to be consistent with recent observations of massive neutron stars. Static properties of neutron stars with the ($Y+K$) phase are discussed, such as gravitational mass to radius, mass to baryon number density relations, and density distribution in the core with the ($Y+K$) phase for typical masses of neutron stars.

We present two developments which enhance the predictive power of empirical shell-model Hamiltonians for cases in which calibration data are sparse. A recent improvement in the $\mathit{abinitio}$ derivation of effective Hamiltonians leads to a much better starting point for the optimization procedure. In addition, we introduce a protocol to avoid overfitting, enabling a more reliable extrapolation beyond available data. These developments will enable more robust predictions for exotic isotopes produced at rare isotope beam facilities and in astrophysical environments.