We show that a very clear signal of the presence of a strong magnetic field during the early stage of a high-energy heavy-ion collision is provided by the decay of the $Z^0$ into dimuon pairs. We find that the process is highly anisotropic, producing pairs mainly out of plane, as signaled by a negative value of $v_2$, and leads to an antimuon transverse momentum distribution which peaks at a higher value of the transverse momentum compared to the peak of the muon transverse momentum distribution. We also show that the process does not produce a significant distortion of the $Z^0$ spectral function. The signal can be identified by comparing the dimuon-invariant mass and the individual muon and antimuon spectra produced in semicentral heavy-ion collisions with the corresponding scaled spectra produced in $p+p$ collisions at the $Z^0$ peak.

We performed a systematic analysis of ground-state properties for isotones of neutron shell closures. Using the Hartree-Fock-Bogoliubov theory with different energy density Skyrme functionals, we calculated structure properties, obtaining consistent agreement with available experimental data. The density-dependent cluster model with folding potential, considering nuclear deformations, is used to predict $\alpha$-decay half-lives for isotones leading to $N=184$ daughter nuclei. A clear, shell-driven pattern is evident in the evolving properties of isotones, established by data for $N=50$, 82, and 126, and extending to theoretical estimates for the unobserved $N=184$ isotones. While the binding energy weakens and peaks at higher isospin asymmetry for heavier neutron shell closures, two-proton and two-neutron separation energies follow distinct linear trends dictated by the shell structure. Furthermore, charge radii evolve systematically, with neutron-skin thickness increasing with isospin-asymmetry but decreasing in magnitude for heavier shells. The shell-driven recurrent patterns of $\alpha$-decay energy and half-life demonstrate a clear dependence on the number of protons outside a closed proton shell core. The consistent patterns observed in this study indicate that the most promising region for synthesizing $N=184$ isotones lies between $Z=112$ and $Z=120$. A key challenge for lower-$Z$ candidates in this range is their higher isospin asymmetry, which contradicts the trend of a narrowing stability window for heavier nuclei.

A systematic study of fission barrier heights and static properties of even-even actinide nuclei from Th to Cf has been performed within the Warsaw macroscopic-microscopic model using the five-dimensional Fourier-over-spheroid shape parametrization. The use of a large deformation grid, containing about $1.3\times {10}^8$ points for each nucleus, allows for a refined and numerically complete exploration of the potential-energy landscape without dividing the configuration space into subregions or applying interpolation. Barrier heights, extracted via the immersion water flow method, show good agreement with empirical evaluations (including the new IAEA RIPL-4 dataset) with mean deviations below 1 MeV. Special attention is given to the long-debated third, hyperdeformed minimum. For Th isotopes, a shallow but distinct third well appears, whereas it is absent in heavier actinides (U, Pu).

Precision measurements of observables in neutron $\beta$ decay are used to test the standard model description of the weak interaction and search for evidence of new physics. The Nab experiment at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source was constructed to measure correlations in neutron decay by utilizing an asymmetric spectrometer and novel detection system to accurately reconstruct the proton momentum and electron energy for each $\beta$ decay. This work describes the detection of neutron $\beta$-decay products in the Nab spectrometer and presents the first full Dalitz plot representation of the phase space of neutron $\beta$ decay for all electrons $>100$ keV. In addition, new constraints are placed on a possible excited neutron state, hypothesized to explain the disagreement between the appearance and disappearance neutron lifetime techniques.

The number and properties of the neutrons and photons emitted in nuclear fission are directly related to the excitation energy of the fission fragments when they are formed at scission. Though not observable experimentally because of the extremely short timescales, the excitation energy of fission fragments can be predicted by microscopic theory based on time-dependent density functional theory (TDDFT). Initial results on the value of the total kinetic energy of fission reactions were very promising, but could not probe all possible fragmentations. In this work, we perform large-scale TDDFT calculations in ${}^{240}\mathrm{Pu}$ enabled by the development of a new TDDFT solver. We obtain TDDFT trajectories covering nearly all possible fragmentations. We find that the total kinetic energy is close to experimental values only for the most likely fission while it is severely underestimated at both small and large asymmetries. This conclusion seems rather independent of the parametrization of the energy functional, both in its particle-hole and particle-particle channels.

We study the internal structure of exotic hadrons, especially focusing on the relation between the compositeness and physical observables. Defined as the probability of finding hadronic molecular components in the wave function, compositeness serves as a quantitative measure of the internal structure of exotic hadrons. We utilize the coupled-channel potential model incorporating both quark and hadron degrees of freedom, which naturally generate the “bare state” responsible for the elementary component as the bound state in the quark channel. The behavior of the compositeness under the variation of the model parameters is investigated by using the $X\left(3872\right)$ as an example. In particular, we analyze the associated scattering phase shifts and the bound-state wave functions to discuss the relation between the compositeness and the scattering observables for a shallow bound state. As a phenomenological application of the present framework, the compositeness of the $X\left(3872\right), T_{cc}\left(3875\right), D_{s0}\left(2317\right)$, and $D_{s1}\left(2460\right)$ is discussed.

We investigate the cluster-breaking effect and spatial distribution of negative-parity states in the ${}_{\mathrm{\Lambda }}{}^{12}\mathrm{B}$ hypernucleus using the Hyper-Brink model with cluster breaking (CB-Hyper-Brink) optimized via control neural network (Ctrl.NN). The results demonstrate that the inclusion of cluster breaking is essential for accurately reproducing the observed low-lying energy levels and for making reliable predictions of the Hoyle-analog state $1_4^{-}$ in ${}_{\mathrm{\Lambda }}{}^{12}\mathrm{B}$. Cluster breaking manifests as strong spin-orbit correlations and the dissolution of ideal cluster configurations, as revealed by the analysis of one-body spin-orbit-operator expectation values and the spatial overlap with projected cluster bases. The interplay between short-range repulsion and intermediate-range attraction in the $\mathrm{\Lambda }N$ interaction induces the cluster reconfiguration effect, which is characterized by the coexistence of $\mathrm{\Lambda }\text{−}\alpha$ and $\mathrm{\Lambda }$-triton correlations; this reconfiguration effect leads to a modest stabilization and shrinkage of cluster structures. The variation in electric quadrupole transition strengths, $B\left(E2\right)$, between the ground and Hoyle-analog states, serves as a sensitive probe for the degree of cluster breaking, providing direct evidence for its physical relevance. These findings highlight the crucial role of cluster breaking in characterizing the hypernuclear structure and offer a comprehensive framework for understanding the interplay between clustering and shell-model dynamics in hypernuclei.

Three-body Faddeev-type equations for bound, resonant, and scattering states in systems with a nuclear core and two nucleons are solved using the momentum-space framework. Two approaches for eliminating the Pauli-forbidden deeply bound states are compared: projecting out those states by using a nonlocal term in the potential, and by using a supersymmetric transformation of the potential. While the former method is preferred by the experimental data for deuteron-${}^4\mathrm{He}$ scattering, the results for bound and resonant states do not indicate a clear superiority of a single method. Instead, systematic differences between them are found.

The low-lying excitation region in ${}^9\mathrm{B}$ has been studied through the ${}^{12}\mathrm{C}(p,\alpha ){}^9\mathrm{B}$ reaction with a proton beam energy of 33 MeV at the Birmingham MC40 Cyclotron. Coincident recoil $\alpha$-particle and ${}^9\mathrm{B}$ breakup products were detected by a silicon double-sided strip detector array and reconstructed to identify signatures of the elusive ${}^9\mathrm{B}(1/2^{+})$ state. Data were collected for two distinct $\alpha$-particle recoil angles, ${31}^{\circ }$ and ${106}^{\circ }$, with a total beam exposure of $\approx 0.52$ mC. $R$-matrix analysis indicates the presence of a state at $E_{\mathrm{x}}=1.83\pm 0.05$ MeV with a width of $\mathrm{\Gamma }=850{\pm }_{88}^{110}$ keV with a confidence level of 99.1% and no signature of any lower-lying state. This result is shown to be consistent with four previous measurements over the last 25 years, signifying strong evidence that the first excited state in ${}^9\mathrm{B}$ lies at a weighted average excitation of $E_{\mathrm{x}}=1.84\pm 0.04$ MeV with $\mathrm{\Gamma }=740{\pm }_{66}^{77}$ keV.

Nuclear coherent population transfer (NCPT) offers numerous potential applications, particularly in next-generation nuclear clocks and nuclear batteries. However, realization of high fidelity, fast operation, and low energy consumption in NCPT remains so far challenging. Here we employ physics-informed neural networks (PINNs) to the population transfer in an open three-level nuclear system with spontaneous emission. The method embeds the systems control equations and boundary conditions into the loss function, thereby enabling automatic learning of optimal laser pulse sequences that drive highly efficient population transfer. We take a short-lived excited state of ${}^{172}\mathrm{Yb}$ and a long-lived state of ${}^{229}\mathrm{Th}$ as representative examples and systematically compare the performance of the PINNs approach with three conventional control strategies. We show that PINNs can achieve higher transfer efficiency with smaller pulse areas and shorter durations across different lifetime regimes. Our results provide a new perspective to overcome the lifetime limitation and enhance the efficiency of nuclear state transfer.

This study presents a comprehensive analysis of the elliptic flow coefficient, $v_2$, for charged hadrons at midrapidity in $d+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$. Utilizing a multiphase transport (AMPT) model in both default and string melting modes, we examine the dependence of $v_2$ on transverse momentum, collision centrality, and particle type. Furthermore, we present $v_2$ across different collision centralities in $d+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$ within the AMPT model with the string melting mode. Our results indicate that the early-stage partonic phase significantly influences $v_2$, as observed by variations in parton scattering cross section. We also studied the effect of final-state hadronic interactions on $v_2$ by varying the hadronic cascading time. Comparisons with STAR and PHENIX experimental data show that the AMPT model effectively captures the transverse momentum dependence of $v_2$, underlining the importance of parton scattering mechanisms and the need for careful interpretation of experimental results in asymmetric systems.

We investigate charge-balance functions for pion, kaon, and proton pairs in proton-proton (pp) collisions at $\sqrt{s}=13$ TeV using Monte Carlo models, pythia8, and epos-lhc, with transverse spherocity to classify event topology and charged-particle multiplicity to select system size. Simulations with pythia8 and epos-lhc reveal that balance-function widths in rapidity and azimuthal angle depend on multiplicity and event shape. In pythia8, widths decrease monotonically with multiplicity, consistent with local charge conservation in a fragmentation-dominated scenario. In contrast, the epos-lhc model, especially when using the core corona implementation, exhibits a more intricate response, where the combined effects of hydrodynamic radial flow and longitudinal diffusion result in narrower azimuthal correlations and broader rapidity correlations. These features are characteristic signatures of collective dynamics, similar to those observed in heavy-ion collisions. Events with low spherocity, which are jetlike in nature, exhibit significantly narrower balance-function widths compared to isotropic events with high spherocity, illustrating that event-shape selection provides clear sensitivity to the underlying dynamics of particle production in pp collisions. The species dependence and event-shape sensitivity of the balance-function widths provide information about the hadronization dynamics and collectivity in small systems. These results demonstrate that multidimensional, particle-species-dependent balance-function measurements can disentangle the underlying mechanisms of charge correlations and mediumlike behavior in high-multiplicity pp collisions.

We apply the Bayesian model selection method (based on the Bayes factor) to optimize $\sqrt{s_{NN}}$-dependence in the phenomenological parameters of the $(3+1)$-dimensional hybrid framework for describing relativistic heavy-ion collisions within the beam energy scan program at the Relativistic Heavy Ion Collider. The effects of various experimental measurements on the posterior distribution are investigated. We also make model predictions for longitudinal flow decorrelation, rapidity-dependent anisotropic flow, and identified particle $v_0\left(p_{\mathrm{T}}\right)$ in $\mathrm{Au}+\mathrm{Au}$ collisions, as well as anisotropic flow coefficients in small systems. Systematic uncertainties in the model predictions are estimated using the variance of the simulation results with a few parameter sets sampled from the posterior distributions.

Nuclear masses of neutron-deficient nuclei play an important role in our understanding of the astrophysical rapid proton $\left(rp\right)$ capture process. With the help of advanced mass spectrometers, nuclear masses of ${}^{61}\mathrm{Ga}$ and ${}^{62}\mathrm{Ge}$ were directly measured with a high precision, yielding a precise proton separation energy of $S_p=2.452\left(38\right)$ MeV for ${}^{62}\mathrm{Ge}$, which is a critical input for characterization of the waiting point ${}^{60}\mathrm{Zn}$ in the $rp$ process. Using the new $S_p$ value, the thermonuclear reaction rate and its associated uncertainties for ${}^{61}\mathrm{Ga}(p,\gamma ){}^{62}\mathrm{Ge}$ have been reevaluated. We find that our new rates are overall larger than those from the statistical models across the range of 0.1–1.8 GK. Within the temperature range of 0.1–0.45 GK the new rate exceeds the REACLIB V2.2 recommended values, whereas above 0.45 GK it falls below them. Simulations of type-I x-ray bursts using mesa demonstrate that the newly determined ${}^{61}\mathrm{Ga}(p,\gamma ){}^{62}\mathrm{Ge}$ rates have a substantial influence on the composition of the burst ashes: the maximum mass fraction increases for nuclei with A = 60–63, even reaching a level of 90% in the burst ashes, despite no significant variation in the light curve.

This work analyzes fusion data for the medium-heavy systems ${}^{58}\mathrm{Ni}+{}^{58}\mathrm{Ni}$ and ${}^{58}\mathrm{Ni}+{}^{54}\mathrm{Fe}$ and the medium-light systems ${}^{48}\mathrm{Ca}+{}^{48}\mathrm{Ca}$ and ${}^{36}\mathrm{S}+{}^{64}\mathrm{Ni}$, and compares them with previous results for ${}^{64}\mathrm{Ni}+{}^{64}\mathrm{Ni}$. While all the systems exhibit negative $Q$ values and signatures of fusion hindrance, the lighter systems do not show a maximum in the astrophysical $S$ factor or a substantial increase in the logarithmic slope at the lowest measured energies. To elucidate these differences, fusion cross sections derived from interaction potentials calculated within the Skyrme energy density functional (SEDF) approach are examined. The analysis indicates that Skyrme forces with a softer incompressibility modulus $K$ $\approx 216\mathrm{MeV}$ best describe the behavior of the medium-heavy systems, where an $S$-factor maximum and an increase in the barrier height emerge at low energies. Applying the same methodology to ${}^{48}\mathrm{Ca}+{}^{48}\mathrm{Ca}$ and ${}^{36}\mathrm{S}+{}^{64}\mathrm{Ni}$ suggests that observing a similar steep falloff in their fusion excitation functions may require measurements at lower bombarding energies. Estimates indicate that energies of approximately $E$ $\approx 44\mathrm{MeV}$ for ${}^{48}\mathrm{Ca}+{}^{48}\mathrm{Ca}$ and $E$ $\approx 50\mathrm{MeV}$ for ${}^{36}\mathrm{S}+{}^{64}\mathrm{Ni}$ corresponding to cross sections of roughly 0.8 and 3 nb, respectively, may be necessary to reveal this behavior.

The MAGNETO-$\nu$ experiment searches for keV-scale heavy neutral leptons (HNLs) through precise measurements of the ${\beta }^{-}$-decay spectrum of ${}^{241}\mathrm{Pu}$. We present spectra comprising a total of 194 million ${\beta }^{-}$ decays recorded using decay energy spectrometry with metallic magnetic calorimeters, representing the most statistically precise measurement of ${}^{241}\mathrm{Pu}{\beta }^{-}$ decay to date. The $\beta$-endpoint energy was determined using $\gamma$ rays and x-rays from an external ${}^{133}\mathrm{Ba}$ calibration source, yielding $Q_{\beta }=22.273\left(33\right)\mathrm{keV}$. The measured spectrum shows no statistically significant deviation from the allowed $\beta$-decay model. From a subset of the high-statistics data, we set an upper limit on the mixing of an 11.5-keV HNL with the electron neutrino, $|U_{e4}{|}^2<1.31\times {10}^{-3}$ at the 95% confidence level.

We compute moments of the isoscalar monopole response of $N=Z$ closed-shell nuclei based on chiral nucleon-nucleon plus three-nucleon interactions. We employ the random-phase approximation (RPA) and two ab initio many-body approaches, the in-medium similarity renormalization group (IMSRG) and coupled-cluster theory (CC). In the IMSRG framework, the moments are obtained as ground-state expectation values, whereas in the CC approach, they are evaluated through excited-state calculations. We find good agreement between the IMSRG and CC results across all nuclei studied. RPA provides a reasonable approximation to the correlated methods if the interaction is soft. From the calculated moments, we extract average energies of the monopole response, compute finite-nucleus incompressibilities, and estimate the incompressibility of symmetric nuclear matter by a fit to a leptodermous expansion. Our extrapolated values are lower than those obtained in nuclear-matter calculations with the same interactions, but the values are consistent with phenomenological ranges.

Multinucleon transfer (MNT) reactions offer a promising pathway to synthesize neutron-rich heavy nuclei, but the mechanism of inverse quasifission, as a key reaction channel of MNT, still remains not well understood. We employ time-dependent Hartree-Fock theory to investigate the reaction mechanism, especially the role of the octupole deformed shell in the MNT reaction of ${}^{160}\mathrm{Gd}+{}^{186}\mathrm{W}$. The results show that inverse quasifission occurs when the deformed projectile and target collide in near tip-tip and tip-side orientations, which favors production of neutron-rich transtarget nuclei. Interestingly, the distributions and single-particle spectra of primary products reveal that the $N=88$ octupole deformed shell in light fragments dominates inverse quasifission instead of the spherical shells of ${}^{208}\mathrm{Pb}$ at a center-of-mass energy of $502.6\text{MeV}$, thus explaining the experimental observation that the yields of the transtarget products are enhanced in the Au region. Further exploration finds that quantum shell effects in inverse quasifission exhibit energy dependence. These results demonstrate that the octupole deformed shell plays a crucial role in the inverse quasifission dynamics, significantly advancing the understanding of the MNT reaction mechanism.

Proton-induced fission has an advantage for studying nuclear reactions because it involves simpler reaction mechanisms compared to reactions induced by heavier nuclei. Moreover, as charged particles, proton beams can be precisely accelerated and controlled over a wide energy range, allowing systematic analysis of fission fragment yields and improving the production efficiency of rare isotopes. In this work, we investigate proton-induced fission of ${}^{238}\mathrm{U}$ and ${}^{232}\mathrm{Th}$ at incident energies of 20–80 MeV, which are relevant to experiments at the isotope separation on-line (ISOL) facility of the Rare isotope Accelerator complex for ON-line experiments (RAON) in South Korea. The stochastic dynamics of the excited compound nuclei is modeled using the Langevin approach, incorporating a charge-asymmetry coordinate as an additional degree of freedom. This extension enables simultaneous determination of both mass and charge distributions of fission fragments. To estimate the contribution of each fission chance in multichance fission (MCF), we adopt the Fermi gas model instead of the General Fission (GEF) code, in order to include nuclear structure effects such as nuclear pairing. We find that our results for the fission fragment mass distribution (FFMD) are consistent with the available experimental data. Furthermore, we consider prompt neutron emission from primary fragments to calculate the independent fission cross sections, which show reasonable agreement with experimental observations. We also observe that, in the case of proton-induced fission of ${}^{232}\mathrm{Th}$, the nuclear level density parameter plays an important role.

Proton-induced quasifree knockout reactions provide a powerful probe of nuclear single-particle structure and reaction dynamics in both stable and neutron-rich nuclei. In this work we develop a unified theoretical framework for the calculation of inclusive $(p,2p)$ and sequential $(p,3p)$ reaction cross sections and fragment momentum distributions at intermediate and relativistic energies. The approach is based on a probabilistic extension of Glauber multiple-scattering theory combined with microscopic nuclear densities obtained from Hartree-Fock-Bogoliubov calculations using Skyrme energy-density functionals. We focus in particular on the sensitivity of total cross sections and longitudinal momentum dispersions to neutron-skin thickness along isotopic chains. Our results indicate that both $(p,2p)$ and $(p,3p)$ reactions exhibit a systematic decrease of cross section and momentum width with increasing neutron excess, reflecting enhanced attenuation and surface bias induced by neutron skins. The effect is significantly stronger for two-proton removal, suggesting that $(p,3p)$ reactions may offer enhanced sensitivity to isovector nuclear structure. These findings establish proton-induced knockout reactions as complementary hadronic probes of neutron skins and the density dependence of the nuclear symmetry energy.