We study quantum-information aspects of neutron-proton scattering in the spin-space $M$-matrix framework. Four representative classes of input states are considered, namely, diagonal mixed states, separable pure states, general two-qubit pure states, and a special Schmidt-like entangled subclass. For each class, ensemble-averaged output mutual information, reduced-state linear entropy, negativity, and geometric quantum discord are calculated in the relative momentum–scattering angle plane. The results show that the outgoing spin correlations are governed jointly by scattering kinematics and by the structure of the incoming quantum ensemble. Input states with stronger intrinsic coherence or entanglement give larger maxima and higher minima in the mutual information, negativity, and geometric quantum discord. The enhanced regions of the mutual information and geometric discord depend on the input states, while the negativity maximum remains concentrated in the high-momentum backward-scattering region. These results extend earlier studies based on product-state entanglement power and provide an ensemble-based description of how spin correlations in neutron-proton scattering arise from the interplay between input-state structure and scattering dynamics.

The nuclear shell model is known to describe the properties of various nuclei extremely well. However, the auxiliary-field quantum Monte Carlo calculations cannot be applied to it with general interactions due to the sign problem. The model has therefore been investigated primarily by variational methods, where the accuracy of the results depends crucially on the ansatz for the wave function. Here we perform the auxiliary-field quantum Monte Carlo calculations in the case of small systems at finite temperature using the complex Langevin method (CLM), which has been successfully applied to various interesting systems with the sign problem over the decade. In particular, we show the existence of a parameter region in which the validity criterion for the CLM is satisfied and the expectation value of the energy obtained by exact diagonalization is correctly reproduced. Thus the CLM can be a complementary approach to the variational method for large systems.

Nuclear density functional theory provides a unified description of finite nuclei and bulk nuclear matter, and is widely used to model the neutron star (NS) equation of state. However, extrapolations to suprasaturation densities require a quantified treatment of uncertainties arising from parameter estimation and functional choices. We present an updated Bayesian inference of a Skyrme energy density functional augmented by a flexible metamodel density dependence at high density. Nuclear observables are computed using a Gaussian emulator of the publicly available Milano hfbcs-qrpa code, enabling efficient exploration of a high-dimensional parameter space. Relative to previous analyses, we extend the calibration set with isospin-sensitive data, including masses and charge radii along selected Ca and Sn isotopic chains, and updated constraints from giant monopole resonances. The resulting posteriors are further constrained by ab initio neutron-matter calculations and astrophysical observations, including recent NICER measurements, yielding consistent crust and core properties of catalyzed NS compatible with current constraints. Bulk nuclear-matter parameters are well approximated by a multivariate Gaussian with covariance matrix provided for direct reuse, while several finite-nucleus parameters exhibit pronounced non-Gaussianity.

The $K$-isomeric states in the heaviest nuclei are among the interesting topics in superheavy-element research. In the present work, we report on the discovery of $\mu \mathrm{s}$ isomers in ${}^{258,259,260}\mathrm{Sg}$ which deexcite with half-lives of ${120}_{-55}^{+578}\mu \mathrm{s}$, $85\pm 6\mu \mathrm{s}$, and $8.5_{-1.8}^{+3.1}\mu \mathrm{s}$, respectively, and are attributed to high-$K$ states formed in multiquasiparticle couplings. In ${}^{261}\mathrm{Sg}$, activity with $12.6_{-1.6}^{+2.2}\mu \mathrm{s}$ half-life was observed and it is suggested to originate from decays of a high-$K$ multiquasiparticle and/or single-particle isomeric states.

Background: Contemporary stopping powers for $fp$-shell nuclei slowing in tantalum can differ by a factor of 2 from the 1963 Lindhard, Scharff, and Schiøtt (LSS) theory [Mat. Fys. Medd. Dan. Vidensk Selsk. 33, no. 14 (1963)] used in Doppler-shift attenuation method (DSAM) lifetime measurements dating back to the 1970s. In recent work by Woodside et al. [Phys. Rev. C 113, 044306 (2026)], it was found that anomalously high collectivity in the $4_1^{+}\to 2_1^{+}$ transition of ${}^{58}\mathrm{Fe}$ given in the Evaluated Nuclear Structure Data File (ENSDF), Nesaraja et al. [Nucl. Data Sheets 111, 897 (2010)] could be traced back as largely due to the use of these historical stopping powers in the Doppler-shift lifetime measurements. Satisfactory agreement with shell-model calculations was obtained from a reanalysis of the 1978 DSAM measurement of Bolotin et al. [Nucl. Phys. A 311, 75 (1978)] once the stopping powers were replaced by up-to-date values.

Purpose: The DSAM measurement on ${}^{54}\mathrm{Cr}$ by the same group, Stuchbery et al. [Nucl. Phys. A 337, 1 (1980)], which used the same experimental methods and procedures, is reexamined.

Method: The computer code used in the original DSAM analysis has been rebuilt and upgraded with the capacity to use contemporary stopping powers. Reduced $E2$ transition strengths derived from the revised lifetimes are compared with shell-model calculations.

Results: The impact of revised stopping powers on the excited-state lifetimes depends on the relative contributions of nuclear and electronic stopping powers. It is primarily the electronic stopping powers that differ from LSS values. Hence, the magnitude of the change in lifetime depends on the lifetime itself. In the present case, the lifetimes increase by 16% to 27%, with the larger increase generally corresponding to shorter lifetimes where electronic stopping dominates.

Conclusions: Revised lifetimes, based on current stopping powers, imply $B\left(E2\right)$ transition rates between states up to the $6_1^{+}$ state in ${}^{54}\mathrm{Cr}$ that compare well with shell-model calculations using the GXFP1A interaction. Better agreement is obtained with the effective charges recently proposed by Ogunbeku et al. [Phys. Rev. Lett. 135, 072501 (2025)], namely $e_{\pi }=1.3$ and $e_{\nu }=0.45$, than with the standard $e_{\pi }=1.5$ and $e_{\nu }=0.5$. The lifetime data together with branching ratios and the shell-model calculations strongly suggest revision of the spins assigned to the levels at 3.786 [currently ${\left(4\right)}^{+}$] and 4.043 MeV (currently $5^{+}$). These levels are suggested to be the $5_1^{+}$ and $6_2^{+}$ states, respectively.

We investigate the influence of the tensor component of the Skyrme interaction on $\alpha$ clustering and $\alpha$ decay in heavy nuclei within the Hartree-Fock-Bogoliubov framework. Ground-state-to-ground-state $\alpha$ decays in even-even Po, Rn, and Ra isotopes are treated microscopically using the formalism proposed by Ward et al. [Phys. Rev. C 88, 064316 (2013)]. By comparing calculations with and without the tensor force, we find that the tensor interaction significantly improves the description of the relative $\alpha$-decay rates by better reproducing the shell evolution of the reduced widths across the $N=126$ shell closure. A microscopic analysis shows that the tensor force modifies the spin-orbit splittings and rearranges single-particle orbitals near the Fermi surface, which in turn changes the pairing correlations and the $\alpha$-cluster formation probability. Although the tensor interaction does not remove the underestimation of the absolute decay widths within the present mean-field framework, it plays an important role in capturing the systematic trends of $\alpha$ clustering in heavy nuclei.

A microscopic study of $\alpha$-decay half-lives is performed to examine the influence of the nuclear medium effect on the $\alpha$-daughter interaction. The conventional double-folding potential is improved by replacing the fixed free-$\alpha$ density with a density-dependent $\alpha$-cluster distribution that varies with the local density of the daughter nucleus. This modification accounts for the change of the $\alpha$-cluster size induced by Pauli blocking and the surrounding nuclear mean field during the decay process. Because $\alpha$ decay is highly sensitive to the surface region of the interaction potential, the medium-induced modification of the $\alpha$ density has a direct impact on the barrier penetrability and calculated half-lives. The calculations are carried out for a wide range of 256 nuclei, with special attention to isotopic chains around shell closures in order to clarify the role of magicity in $\alpha$-decay systematics. Nuclear deformation is included through deformed daughter-density distributions, and its effect on the orientation-dependent potential and half-life is investigated. The influence of the exchange part of the effective nucleon-nucleon interaction is also analyzed by comparing zero-range and finite-range exchange treatments of the M3Y-Paris interaction. The results show that the nuclear medium effect improves the description of experimental half-lives, while deformation and finite-range exchange provide additional refinements, especially for open-shell and deformed nuclei. The observed behavior around magic numbers confirms the strong connection between shell structure, $\alpha$-cluster formation, and decay probability. These findings indicate that the combined treatment of medium effects, deformation, and exchange interaction is important for a reliable microscopic description of $\alpha$ decay.

Low-spin excited states in ${}^{68}\mathrm{Zn}$ have been studied at the High Intensity Gamma-Ray Source ($\mathrm{HI}\gamma \mathrm{S}$) from the ground state up to the particle emission threshold using the nuclear resonance fluorescence technique and the newly developed clover array. Low-spin levels were excited by linearly polarized, 2.90–9.79 MeV photon beams. Spin-parity quantum numbers as well as associated $M1$ and $E1$ decay strengths were determined for a large fraction of the 158 states observed. In addition, long-duration coincidence measurements at 9.46 and 9.79 MeV enabled the investigation of the level scheme near the ground state. The results have been interpreted with shell-model calculations using two different model spaces and several effective interactions often used to describe nuclei in this mass region. While the structure near the ground state can be understood in terms of excitations involving solely valence nucleons, core breaking is required to account for the evolution of the total $M1$ strength at excitation energies above approximately 5 MeV.

Background: Mass-asymmetric fission in the actinide nuclei is dominated by shell gaps in the heavy fragment, proposed to be due to octupole deformed shell gaps between $Z=52$ and 56. The mass-asymmetric fission of nuclei lighter than lead shows the influence of different shell gaps, centered around $Z=34,36$ and $Z=44,46$. There is indirect evidence that the $Z=44$ shell gap may influence fission in isotopes as heavy as ${}^{240}\mathrm{Pu}$.

Purpose: Examine the fission modes present in ${}^{216–221}\mathrm{Ra}$ (proton number $Z=88$) where the $Z=44$ shell gap may be expected to influence fission at mass symmetry, and investigate their evolution along the Ra chain.

Method: Fission of ${}^{216–221}\mathrm{Ra}$ was induced in the heavy-ion fusion of ${}^{12,13}\mathrm{C}$ with ${}^{204,206,208}\mathrm{Pb}$ at excitation energies between 24 and 28 MeV. Fission fragments were detected in coincidence and their mass ratios and total kinetic energies (TKEs) reconstructed.

Results: The presence of the asymmetric modes of fission near $Z=52,56$ and the presence of a mode located at symmetry ($Z=44$) with TKE higher than the wide mass-symmetric (liquid-drop) fission is established over the entire ${}^{216–221}\mathrm{Ra}$ chain. In ${}^{216–219}\mathrm{Ra}$, two-dimensional mass-ratio-TKE fits suggest the additional influence of fission driven by $Z=46$ and/or its complementary fragment at $Z=42$.

Conclusions: High-statistics measurements of heavy-ion fusion-fission, combined with statistically rigorous analysis, enables high-fidelity decomposition into Gaussian fission modes, even at relatively high excitation energies. Consistent evidence for a high-TKE shell-driven mode at $Z=44$ contributes to a growing body of evidence that the $Z=44$ mode shell gap is important both in the preactinides and in the actinides, and to the idea that bimodal symmetric fission may occur whenever a favorable shell gap coincides with mass symmetry.

The synthesis of superheavy nuclei (SHN) through fusion reactions is a critical area of nuclear physics, offering insights into nuclear stability and the limits of the periodic table. However, theoretical predictions of evaporation residue cross sections ${\sigma }_{\mathrm{ER}}$ remain challenging due to large uncertainties arising from complex reaction mechanisms and sensitive model parameters. In this work, the average production probabilities of SHN with atomic number $Z\ge 110$ are systematically analyzed, based on the barrier tunneling concept. Together with the empirical barrier distribution method for describing capture, a phenomenological formula, EBD3, is proposed, which reproduces 58 measured ${\sigma }_{\mathrm{ER}}$ within one order of magnitude, with a root-mean-square deviation of 0.369. The formula successfully captures key quantities in the fissionlike process, including fission barrier height, mass asymmetry, depth of the capture pocket, and the effective fusion barrier height. Predictions for the synthesis of element 119 are presented, identifying promising projectile-target combinations such as ${}^{50}\mathrm{Ti}+{}^{249}\mathrm{Bk}$ with a maximum cross section of $54.9_{-29.0}^{+61.3}$ fb at the excitation energy of 36.5 MeV. The maximum cross section falls to $3.2_{-1.7}^{+3.6}$ fb for ${}^{54}\mathrm{Cr}+{}^{243}\mathrm{Am}$ at the optimal incident energy of 244 MeV.

The generation of fission fragment spin as a probe of scission mechanism remains a question of considerable interests. We present here microscopic calculations of rapidly rotating fission of the compound nucleus ${}^{240}\mathrm{Pu}$ under varying initial conditions within the time-dependent density functional theory framework. The obtained spin ratio of light to heavy nascent fragments is unchanged up to high spins but diminished as excitation energies increase, indicating sawtooth structures in fragment spins would fade away at high excitations rather than high angular momentum. Results also show elongated neck configurations and nonaxially symmetric deformations of fragments owing to rapid rotations. These findings offer insights into the scission mechanism of rapidly rotating compound nuclei with strong fragment spin polarizations.

Nuclear pear-shaped, or octupole, deformation enhances the sensitivity of nuclei to fundamental symmetry-violating effects, including CP violation, yet its quantitative characterization, particularly its quantum fluctuations, remains challenging. We establish a multiscale validation strategy that combines low-energy electromagnetic transitions with intermediate-energy nucleus-nucleus collisions to probe octupole deformation and its associated quantum shape fluctuations. Using a microscopic collective Hamiltonian based on density functional theory, we first reproduce the electric octupole transition strengths of ${}^{226}\mathrm{Ra}, {}^{238}\mathrm{U}$, and ${}^{244}\mathrm{Pu}$, thereby validating the underlying nuclear-structure inputs. Within the isospin Boltzmann-Uehling-Uhlenbeck transport model, we then verify the geometric response by correlating initial participant eccentricities with self-correlation-subtracted two-particle flow observables. The resulting triangular-flow observable $v_3{\left\{2\right\}}^2$ scales with the mean-square octupole deformation $\langle {\beta }_3^2\rangle$. Crucially, the event-by-event fluctuation $\sigma \left[v_3{\left\{2\right\}}^2\right]$ exhibits a robust linear correlation with the octupole quantum-shape fluctuation $\sqrt{\langle {\beta }_3^4\rangle -{\langle {\beta }_3^2\rangle }^2}$. This provides an experimentally accessible collision observable for probing quantum fluctuations associated with nuclear deformation.

This work proposes Quantum Monte Carlo (QMC) methods for interacting many-fermion systems by leveraging the stochastic gauge freedom, originally developed in Gaussian phase-space QMC, within the phaseless auxiliary-field QMC (AFQMC) framework. In particular, the approach reinterprets the conventional force bias in phaseless AFQMC as a drift gauge and explores Fermi gauges based on the natural orbitals of a reduced one-body density matrix defined via a mixed estimator, yielding stochastic, time-dependent Hartree-Fock-like dynamics. A symmetry-projection sampling scheme is also introduced to improve sampling efficiency. As a proof of concept, these gauge-augmented AFQMC methods are applied to a simple shell-model Hamiltonian: the Lipkin-Meshkov-Glick model. Numerical results illustrate the potential of stochastic gauges to enhance accuracy and reduce fluctuations, underscoring the promise for advancing these techniques toward more realistic shell-model applications.

Conventional nuclear mass formulas, predicated on the charge independence of nucleon-nucleon ($NN$) interactions, generally parametrize the neutron-proton asymmetry $[I=(N-Z)/A]$ using even powers or absolute values. Previously, an $I^3$ term was incorporated into the classical liquid drop model to examine the influence of isospin symmetry breaking (ISB) on nuclear mass. Although this term captures the ISB effect especially in the mass region of large isospin asymmetry, its directly fitted coefficient is often overshadowed by the dominant macroscopic background. This may lead to numerically entangled and physically unreasonable values, which would undermine the credibility of subsequent conclusions regarding the breaking effect. To address this issue, this paper utilizes a double-difference analysis of binding energies to extract a more physically rational coefficient for the $I^3$ term. Benefiting from the isospin-related terms, the coefficients of these terms all have been refined, during which the volume symmetry energy coefficient was readjusted to around −29 MeV. This is slightly lower than the typical results found in previous models. Furthermore, the ratio of surface symmetry energy coefficient to the volume symmetry energy coefficient is in the range of 1.6–1.8, which is in good agreement with the results reported in previous works. More importantly, the value of the ISB term coefficient, as expected, was refined to $-3.7\pm 0.65$ MeV. Although the contribution of this term to nuclear mass in the liquid drop model is small, the extracted values remain highly stable, particularly when approaching the neutron-rich region.

A consistent finite-temperature microscopic theory for the response of strongly coupled superfluid fermionic systems is formulated. We start from the general many-body Hamiltonian with the vacuum (bare) two-fermion interaction and derive the equation of motion (EOM) for the thermally averaged two-time two-fermion correlation function, which determines the spectrum of the system under study. The superfluidity is introduced via the Bogoliubov transformation of the fermionic field operators, and the entire formalism is carried out in the basis of Bogoliubov's quasiparticles, keeping the complete $4\times 4$ block matrix structure of the two-fermion EOM. Fully correlated static and dynamical interaction kernels of the resulting EOM are discussed. A special focus is then placed on the latter kernel, which is advanced to a factorized form, enabling a minimal truncation of the many-body problem while keeping important effects of emergent collectivity and mapping to the quasiparticle-vibration coupling (qPVC). As in the zero-temperature and nonsuperfluid cases, the qPVC can be associated with a new order parameter, the qPVC vertex. In the thermal superfluid theory, this vertex as well as the components of the dynamical kernel acquire an extended form including thermally unblocked transition amplitudes.

We investigate the Gamow-Teller (GT) transition strength distributions in the light carbon isotopes ${}^{12,14,16}\mathrm{C}$ within the framework of the deformed quasiparticle random-phase approximation (DQRPA). Nuclear deformation is explicitly incorporated through Skyrme-Hartree-Fock mean-field calculations combined with the QRPA formalism. The residual particle-hole $\left(\text{p-h}\right)$ and particle-particle $\left(\text{p-p}\right)$ interactions are derived from Brückner $G$-matrix calculations based on the CD-Bonn potential, and their impact on the low-lying GT strengths is systematically examined by varying the corresponding interaction strengths. We find that nuclear deformation, particularly that induced by a reduced spin-orbit strength, plays a significant role in interpreting the GT strength distribution of ${}^{12}\mathrm{C}$. In contrast, the calculated ${\mathrm{GT}}^{(-)}$ strength distribution of ${}^{14}\mathrm{C}$ in the spherical limit reproduces the essential features of the experimental $(p,n)$ charge-exchange data. The case of ${}^{16}\mathrm{C}$ reveals additional high-lying GT strength associated with deformation-induced configuration mixing.

We report measurements of the total two-neutron stripping cross section for the ${}^{197}\mathrm{Au}({}^{18}\mathrm{O},{}^{16}\mathrm{O}){}^{199}\mathrm{Au}$ reaction across the energy range $E_{\mathrm{Lab}}$ = 63–125 MeV, corresponding to $0.8\le E_{\mathrm{Lab}}/V_B^{\mathrm{Lab}}\le 1.6$. The experiment employed the stacked-foil activation technique, where eight thin gold targets were irradiated sequentially arranged in a stack by an ${}^{18}\mathrm{O}$ beam. The resulting ${}^{199}\mathrm{Au}$ activities were measured via offline $\gamma$-ray spectroscopy. The production of ${}^{199}\mathrm{Au}$ was confirmed by observing its characteristic $\gamma$ rays ($\gamma$-ray transitions in ${}^{199}\mathrm{Hg}$ following the ${\beta }^{-}$ decay of ${}^{199}\mathrm{Au}$), and further validated through decay-curve analysis of the ${}^{199}\mathrm{Au}$ half-life. Absolute cross sections for the two-neutron stripping channel were extracted and compared with theoretical model predictions. The measured cross sections increase sharply near the Coulomb barrier, from $0.96\pm 0.65$ mb at $E_{\mathrm{Lab}}/V_B^{\mathrm{Lab}}=0.80$ to approximately 40–42 mb at energies above the barrier. Theoretical calculations using the semiclassical GRAZING model systematically underestimate the data, particularly at sub-barrier energies, suggesting limitations in its treatment of pair-correlated transfer. Coupled-reaction-channel calculations performed with the $\mathrm{FRESCO}$ code indicate that two-neutron stripping mechanism is dominated mainly by simultaneous transfer of two neutrons rather than the sequential two-step process. The data are best reproduced by a cluster model with reduced spectroscopic amplitudes, pointing to the role of pairing correlations and configuration mixing in the transfer process. This work provides new absolute cross-section data for two-neutron transfer on a heavy target at sub-barrier energies and highlights challenges in current theoretical descriptions of pair-transfer reactions near the Coulomb barrier.

Background: Neutron reactions off lithium isotopes up to 50 MeV are important for nuclear data science, around the International Fusion Material Irradiation Facility (IFMIF) facility in particular.

Purpose: We aim at constructing a semimicroscopic reaction model that describes neutron elastic scattering off ${}^6\mathrm{Li}$ up to 50 MeV, taking the breakup channels of ${}^6\mathrm{Li}$ into account.

Methods: We adopt the continuum-discretized coupled-channels method (CDCC) with an $\alpha +p+n$ three-body model of ${}^6\mathrm{Li}$. We employ the $g$-matrix effective interaction by Jeukenne, Lejeune, and Mahaux (JLM). The renormalization factors of the real and imaginary parts of the JLM interaction are treated as free parameters.

Results: The renormalization parameter of the real part of the JLM interaction is found to be constant ($=1.1$), whereas that for the imaginary part has a smooth energy dependence. The four-body CDCC calculation with these parameters well describes the angular distributions of both proton and neutron elastic scatterings as well as the neutron total cross section and proton total-reaction cross section. The applicable energy range is found to be from 7 MeV to 50 MeV.

Conclusions: We have constructed a reliable reaction model for describing nucleon-${}^6\mathrm{Li}$ scattering between 7 MeV and 50 MeV. This model can directly be applied to inelastic scattering and breakup reactions for ${}^6\mathrm{Li}$ with the help of the complex scaling method.

Angular distributions for the ${}^{12}\mathrm{C}(p,p^{\prime }){}^{12}\mathrm{C}^{*}\left(7.65\mathrm{MeV}\right)$ reaction populating the Hoyle state have been measured at incident proton energies between 10.8 and 18.0 MeV. It extends the available experimental cross section data in the intermediate energy region and suggests a small resonance around 12.0 MeV. The measured cross sections along with the available data were used to evaluate the proton-induced deexcitation rates of the Hoyle state. The resulting enhancement factors for the triple-$\alpha$ reaction rate are found to differ substantially throughout the calculated temperature range, $0.1–10.0$ GK, and can be as much as $22\%$ higher than the previous estimate that relied on sparse experimental data. The observed deviation highlights the sensitivity of the enhancement to the underlying inelastic scattering cross sections. Further, the experimental data provides more reliable constraints for modeling ${}^{12}\mathrm{C}$ production in hot and dense stellar environments, especially in proton-rich astrophysical environments.