Numerous measurements of ${}^{239}\mathrm{Pu}$ fission cross sections are available for incident neutron energies below 30 MeV. On the other hand, there are no measurements of partial fission cross sections. We propose, in this paper, to give an estimate of these cross sections between 5 and 30 MeV from measurements and calculations of prompt fission neutron spectra and multiplicities. These new cross sections provide a better description of experimental prompt neutron data.

The reaction dynamics for the proton halo nucleus ${}^8\mathrm{B}$ $+$ ${}^{\mathrm{nat}}\mathrm{Zr}$ is explored through an elastic scattering measurement at the sub-Coulomb barrier energy of 26.5 MeV. The differential angular distribution has been measured and the total reaction cross section as well as the interaction distance are derived via an optical model analysis. The present result is combined with relevant values for ${}^8\mathrm{B}$ in comparison with ${}^6\mathrm{He}$, ${}^7\mathrm{Be}$, ${}^{6,7}\mathrm{Li}$, and ${}^{16}\mathrm{O}$ on various targets through a consistent optical model analysis at sub- and near-barrier energies. The results demonstrate the proton halo nature of this exotic nucleus, which exhibits larger values for both the total reaction and interaction radii observables, than those determined for the proton-rich radioactive nucleus ${}^7\mathrm{Be}$ as well as for other stable weakly bound projectiles. Similar results are found for the neutron halo nucleus ${}^6\mathrm{He}$. The present elastic scattering results are also described well with continuum-discretized coupled-channels calculations, exhibiting a weak coupling to continuum.

Halos epitomize the fascinating interplay between weak binding, shell evolution, and deformation effects, especially in nuclei near the drip line. In this Letter, we apply the state-of-the-art ab initio valence-space in-medium similarity renormalization group approach to predict potential candidates for one- and two-neutron halo in the intermediate-mass region. Notably, we use spectroscopic factors (SF) and two-nucleon amplitudes (TNA) as criteria for suggesting one- and two-neutron halo candidates, respectively. This approach is not only theoretically sound but also amenable to experimental validation. Our research focuses on Mg, Al, Si, P, and S neutron-drip-line nuclei, offering systematic predictions of neutron halo candidates in terms of separation energies, SF (TNA), and average occupation. The calculation suggests the ground states of ${}^{40,42,44,46}\mathrm{Al}$, ${}^{41,43,45,47}\mathrm{Si}$, ${}^{46,48}\mathrm{P}$, and ${}^{47,49}\mathrm{S}$ are promising candidates for one-neutron halos, while ${}^{40,42,44,46}\mathrm{Mg}$, ${}^{45,47}\mathrm{Al}$, ${}^{46,48}\mathrm{Si}$, ${}^{49}\mathrm{P}$, and ${}^{50}\mathrm{S}$ may harbor two-neutron halos. In addition, the relative mean-square neutron radius between halo nuclei and inner core is calculated for suggested potential neutron halos. Finally, the relations of halo formations and shell evolution are discussed.

The ${}^7\mathrm{He}$ nucleus was studied by the $(d,p)$ reaction at $29A\mathrm{MeV}$ beam energy. The ${}^7\mathrm{He}$ spectrum was measured up to 8 MeV above the ${}^6\mathrm{He}+n$ threshold. The forward-backward asymmetry in the neutron emission from unbound states of ${}^7\mathrm{He}$ has been found. That implies the presence of a positive parity partial wave in the ${}^7\mathrm{He}$ spectrum.

A lepton-neutron potential in configuration space is obtained. It is based on the Coulomb plus hyperfine interaction Hamiltonian integrated over the neutron charge and magnetic densities. Different parametrizations of the neutron electromagnetic form factors are compared. It is given in the operator form with central, spin-spin, tensor, and spin-orbit terms. The potentials for lowest partial wave states are presented. We compute the lepton-neutron low-energy parameters for the $S$ waves, estimate the zero-energy cross sections for higher angular momentum states, and point out a possible divergence in the partial wave summation due to the spin-orbit potential.

We study the evolution of $K^{\pi }=6^{+}$ and $8^{-}$ two-quasiparticle (q.p.) configurations in the isotopic and isotonic chains of even-even deformed nuclei around ${}^{178}\mathrm{Hf}$ and their ability to describe series of observed $K$-isomer excitations within the framework of a Skyrme Hartree-Fock-BCS (SHFBCS) approach using SIII interaction and seniority pairing strengths with self-consistent blocking. We apply the approach along the prescription of Minkov et al. [Phys. Rev. C 105, 044329 (2022)] used to describe $K$ isomers in the actinide and transfermium mass regions. The calculations allow us to identify the regions where proton or neutron configurations or their mixture may be responsible for the $K$-isomer formation. The obtained results provide a detailed test for the Skyrme SIII interaction used and outline the limits of applicability of the overall SHFBCS approach in the regions of well deformed nuclei. The study suggests that similar systematic analysis can be implemented in the heavier mass regions whenever enough data are available.

Complex processes of fermionic systems ranging from protein folding to nuclear fission often follow a low-dimensional reaction path parametrized in terms of a few collective variables. In nuclear theory, variables related to the shape of the nuclear density in a mean-field picture are key to describing the large amplitude collective motion of the neutrons and protons. Exploring the adiabatic energy landscape spanned by these degrees of freedom reveals the possible reaction channels while simulating the dynamics in this reduced space yields their respective probabilities. Unfortunately, this theoretical framework breaks down whenever the systems encounters a quantum phase transition with respect to the collective variables. Here, we introduce a novel generative deep-learning algorithm designed to build reaction paths that ensure that the many-fermion wave function stays differentiable with respect to the collective variables. This approach is applicable to any fermionic system described by a coherent state. We use the case of potential energy curves in the ${}^{16}\mathrm{O}$ nucleus within the Hartree-Fock theory to illustrate its main features.

Measurements of the $p_{\mathrm{T}}$-dependent flow vector fluctuations in Pb–Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$ using azimuthal correlations with the ALICE experiment at the Large Hadron Collider are presented. A four-particle correlation approach [ALICE Collaboration, Phys. Rev. C 107, L051901 (2023)] is used to quantify the effects of flow angle and magnitude fluctuations separately. This paper extends previous studies to additional centrality intervals and provides measurements of the $p_{\mathrm{T}}$-dependent flow vector fluctuations at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$ with two-particle correlations. Significant $p_{\mathrm{T}}$-dependent fluctuations of the ${\vec{V}}_2$ flow vector in Pb–Pb collisions are found across different centrality ranges, with the largest fluctuations of up to $\sim 15\%$ being present in the 5% most central collisions. In parallel, no evidence of significant $p_{\mathrm{T}}$-dependent fluctuations of ${\vec{V}}_3$ or ${\vec{V}}_4$ is found. Additionally, evidence of flow angle and magnitude fluctuations is observed with more than $5\sigma$ significance in central collisions. These observations in $\text{Pb–Pb}$ collisions indicate where the classical picture of hydrodynamic modeling with a common symmetry plane breaks down. This has implications for hard probes at high $p_{\mathrm{T}}$, which might be biased by $p_{\mathrm{T}}$-dependent flow angle fluctuations of at least 23% in central collisions. Given the presented results, existing theoretical models should be reexamined to improve our understanding of initial conditions, quark–gluon plasma properties, and the dynamic evolution of the created system.

The differential cross section and polarization observables for the elastic reaction induced by deuteron scattering off electrons at rest are calculated in the one-photon-exchange (Born) approximation. Specific attention is given to the kinematical conditions, that is, to the specific range of incident energy and transferred momentum. The peculiar interest of this reaction is to access very small transferred momenta. Numerical estimates are given for polarization observables that describe the of single- and double-spin effects, provided that the polarization components (both vector and tensor) of each particle in the reaction are determined in the rest frame of the electron target.

A dynamical model based on a phenomenological charm quark-nucleon ($c-N$) potential $v_{cN}$ and the Pomeron-exchange mechanism is constructed to investigate the $J/\psi$ photoproduction on the nucleon from threshold to invariant mass $W=300$ GeV. The $J/\psi -N$ potential, $V_{J/\psi N}\left(r\right)$, is constructed by folding $v_{cN}$ into the wave function ${\varphi }_{J/\psi }\left(c\overline{c}\right)$ of $J/\psi$ within a constituent quark model (CQM) of Segovia et al. [Int. J. Mod. Phys. E 22, 1330026 (2013)]. A photoproduction amplitude is also generated by $v_{cN}$ by a $c\overline{c}$-loop integration over the $\gamma \to c\overline{c}$ vertex function and ${\varphi }_{J/\psi }\left(c\overline{c}\right)$. No commonly used vector meson dominance assumption is used to define this photoproduction amplitude which is needed to describe the data near the threshold. The $c-N$ potential $v_{cN}\left(r\right)$ is parameterized in a form such that the predicted $V_{J/\psi N}\left(r\right)$ at large distances has the same Yukawa potential form extracted from a lattice QCD (LQCD) calculation of Kawanai and Sasaki, [Phys. Rev. D 82, 091501(R) (2010)]. The parameters of $v_{cN}$ are determined by fitting the total cross-section data of Jefferson Laboratory (JLab) by performing calculations that include $J/\psi -N$ final-state interactions (FSI). The resulting differential cross sections $d\sigma /dt$ are found in good agreements with the data. It is shown that the FSI effects dominate the cross section in the very near-threshold region, allowing for sensitive testing of the predicted $J/\psi -N$ scattering amplitudes. By imposing the constraints of $J/\psi -N$ potential extracted from the LQCD calculation of Kawanai and Sasaki, [Phys. Rev. D 82, 091501(R) (2010)], we have obtained three $J/\psi -N$ potentials which fit the JLab data equally well. The resulting $J/\psi -N$ scattering lengths are in the range of $a=[-0.05,-0.25]$ fm. With the determined $v_{cN}\left(r\right)$ and the wave functions generated from the same CQM, the constructed model is used to predict the cross sections of photoproduction of ${\eta }_c\left(1S\right)$ and $\psi \left(2S\right)$ mesons for future experimental tests.

We assess the impact of two-particle–two-hole excitations on the semi-inclusive electron scattering process $(e,e^{\prime }p)$ using a fully relativistic nuclear model calculation that precisely incorporates antisymmetrization. The calculation encompasses all contributions involving the exchange of a single pion and the excitation of a $\mathrm{\Delta }$ resonance. Our results are compared with $(e,e^{\prime }p)$ data on carbon at kinematics where two-nucleon emission dominates. This work represents an essential step towards the microscopic computation of the two-particle–two-hole contribution to semi-inclusive neutrino reactions, crucial in the analysis of neutrino oscillation experiments.

Estimates for the quantum electrodynamical (QED) and dispersion effects on the spin asymmetry of perpendicularly polarized electrons scattered from a ${}^{208}\mathrm{Pb}$ nucleus are given. The QED effects are calculated nonperturbatively in terms of their respective potentials. For dispersion, the transient nuclear excitations of ${}^{208}\mathrm{Pb}$ with low multipolarity and energy below 30 MeV are accounted for. Collision energies up to 1 GeV are considered. The results can help to explain the measured spin asymmetry near 1 GeV at forward angles.

Large-scale nuclear shell-model calculations are performed in Xe, Cs, and Ba isotopes up to mass 142 $(Z\ge 50 \text{and} N\ge 82)$ assuming ${}^{132}\mathrm{Sn}$ as a doubly magic core. All the single-particle levels in the one-major shells, six neutron $(1f_{7/2},$ $2p_{3/2},$ $2p_{1/2},$ $0h_{9/2},$ $1f_{5/2}, \text{and} 0i_{13/2})$ orbitals, and five proton $(0g_{7/2},$ $1d_{5/2},$ $1d_{3/2},$ $0h_{11/2}, \text{and} 2s_{1/2})$ orbitals, are considered. For an effective two-body interaction, only one set of the multipole pairing and quadrupole-quadrupole interactions between neutrons and protons is employed and the strengths of the two-body interactions are set constant for all the nuclei considered. These interactions are phenomenologically determined to reproduce the experimental energy spectra in two-body systems. Single-particle energies are set constant for all the nuclei except the neutron $0i_{13/2}$ intruder orbital. Some of the isomeric states are analyzed in terms of the shell-model configurations. In this mass region, octupole correlated states are found in the low-lying energy, for which the collective octupole vibrational motion is involved. These states are constructed by phenomenologically introducing a collective octupole-phonon built on top of each shell-model state. Octupole vibrational bands naturally emerge in this treatment.

We construct efficient emulators for the ab initio computation of the infinite nuclear matter equation of state. These emulators are based on the subspace-projected coupled-cluster method for which we here develop a new algorithm called small-batch voting to eliminate spurious states that might appear when emulating quantum many-body methods based on a non-Hermitian Hamiltonian. The efficiency and accuracy of these emulators facilitate a rigorous statistical analysis within which we explore nuclear matter predictions for $>{10}^6$ different parametrizations of a chiral interaction model with explicit $\mathrm{\Delta }$-isobars at next-to-next-to leading order. Constrained by nucleon-nucleon scattering phase shifts and bound-state observables of light nuclei up to ${}^4\mathrm{He}$, we use history matching to identify nonimplausible domains for the low-energy coupling constants of the chiral interaction. Within these domains we perform a Bayesian analysis using sampling and importance resampling with different likelihood calibrations and study correlations between interaction parameters, calibration observables in light nuclei, and nuclear matter saturation properties.

Nuclear saturation and the symmetry energy are key properties of low-energy nuclear physics that depend on fine details of the nuclear interaction. The equation of state around saturation is also an important anchor for extrapolations to higher densities and studies of neutron stars. Here we develop a unified statistical framework that uses realistic nuclear forces to link the theoretical modeling of finite nuclei and infinite nuclear matter. We construct fast and accurate emulators for nuclear-matter observables and employ an iterative history-matching approach to explore and reduce the enormous parameter domain of $\mathrm{\Delta }$-full chiral interactions. We perform rigorous uncertainty quantification and find that model calibration including ${}^{16}\mathrm{O}$ observables gives saturation predictions that are more precise than those that only use few-body data.

The semimicroscopic particle-hole dispersive optical model is adapted for a description of the main properties of charge-exchange giant spin-multipole resonances in medium-heavy closed-shell parent nuclei. The adapted model is implemented to evaluate the strength functions, transition densities, and branching ratios of direct one-nucleon decay for charge-exchange giant spin-dipole resonances in the ${}^{48}\mathrm{Ca}, {}^{90}\mathrm{Zr}, {}^{132}\mathrm{Sn}$, and ${}^{208}\mathrm{Pb}$ parent nuclei. Some of the calculation results are compared with available experimental data.

Lepton pair photoproduction provides a unique probe of the strong electromagnetic field produced in ultrarelativistic heavy-ion collisions. To map out the broadening behavior of the lepton pair transverse momentum with respect to the back-to-back correlation structure, we present a theoretical model based on the equivalent photon approximation, and then we update it to make direct comparisons with the recent experimental measurements. We find that the model calculations can describe well not only the average transverse momentum squared of $e^{+}{e}^{-}$ pairs in Au-Au collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$, but also the acoplanarity of ${\mu }^{+}{\mu }^{-}$ pairs in Pb-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV. Furthermore, the model predictions are also able to reproduce the measured lepton pair mass and transverse momentum squared distributions.

We calculate the elliptic flow of deuterons in $\mathrm{Pb}+\mathrm{Pb}$ collisions at 2.76 TeV per colliding nucleon-nucleon pair and show that it can be used to discriminate between direct statistical production and coalescence. The emission from the fireball is parametrized and tuned to reproduce transverse momentum spectra and the elliptic flow of protons and pions. Coalescence leads to higher deuteron elliptic flow than statistical production and agrees better with experimental data. We attribute this observation to the varying size of the nucleon-producing region for the emission in different azimuthal angles.