A reliable way of calculating the width, $\mathrm{\Gamma }$, of an extremely narrow quantum resonance is suggested. The proposed method is based on expanding the Jost function in the Taylor series around the real resonance energy, $E_r$, and looking for its zero at the nearby complex point $E_r-i\mathrm{\Gamma }/2$. The coefficients of such an expansion can be obtained by solving a set of coupled differential equations. Using two simple exactly solvable models, it is demonstrated that the method is efficient and accurate.

A standard way to solve the Schrödinger equation is to discretize the radial coordinates and apply a numerical method for a differential equation, such as the Runge-Kutta method or the Numerov method. Here I employ a discrete basis formalism based on a finite mesh method as a simpler alternative, with which the numerical computation can be easily implemented by ordinary linear algebra operations. I compare the numerical convergence of the Numerov integration method to the finite mesh method for calculating penetrabilities of a one-dimensional potential barrier and show that the latter approach has better convergence properties.

High-spin states of ${}^{128}\mathrm{La}$ have been populated by the ${}^{118}\mathrm{Sn}({}^{14}\mathrm{N},4n){}^{128}\mathrm{La}$ reaction at a beam energy of 69 MeV. The previously known level scheme of ${}^{128}\mathrm{La}$ is extended with the addition of 27 $\gamma$ transitions. A new negative-parity band with the same $\pi h_{11/2}\otimes \nu d_{5/2}$ configuration as that of the yrare band is observed in ${}^{128}\mathrm{La}$. This pair of negative-parity bands is suggested to be candidate chiral doublet bands, which is supported by the particle rotor model calculations. Meanwhile, the newly identified negative-parity chiral doublet bands together with the previously known pair of positive-parity chiral doublet bands constitute a case of multiple chiral doublet bands in the odd-odd nucleus ${}^{128}\mathrm{La}$. Furthermore, systematic studies of multiple chiral doublet bands are presented in this work.

Muonic atom transitions have been measured for almost all stable nuclei to extract nuclear structure properties, including nuclear charge radii and quadrupole moment. To investigate the possibilities of extracting higher-order radial moments of nuclear charge density from muonic atom spectroscopy, a theory-to-theory benchmark analysis based on a model-independent density distribution, i.e., the Fourier-Bessel series expansion instead of two-parameter Fermi distribution, is performed by taking ${}^{208}\mathrm{Pb}$ as an example, where nuclear charge density obtained from the relativistic continuum Hartree-Bogoliubov calculation is used as the benchmark. It is found that the extractions of the higher-order moments, i.e., the fourth and sixth moments in addition to the second moment, are feasible with high accuracy. Moreover, the charge form factor in the low-$q$ region can also be well extracted.

We improve a nucleon coalescence model to include the coordinate-momentum correlation in nucleon joint distributions, and apply it to Pb-Pb collisions at $\sqrt{s_{NN}}=2.76\mathrm{TeV}$ to study production properties of deuterons ($d$), helions (${}^3\mathrm{He}$), and tritons ($t$). We give formulas of the coalescence factors $B_2$ and $B_3$, and naturally explain their behaviors as functions of the collision centrality and the transverse momentum per nucleon $p_T/A$. We reproduce the transverse momentum spectra, averaged transverse momenta, and yield rapidity densities of $d, {}^3\mathrm{He}$, and $t$, and find the system effective radius obtained in the coalescence production of light nuclei behaves similarly to Hanbury Brown–Twiss interferometry radius. We particularly give expressions of yield ratios $d/p, {}^3\mathrm{He}/d, t/p, {}^3\mathrm{He}/p, d/p^2, {}^3\mathrm{He}/p^3, t/{}^3\mathrm{He}$ and argue their nontrivial behaviors can be used to distinguish production mechanisms of light nuclei.

The recently published CREX results suggest a rather peculiar picture for the density dependence of the symmetry energy. Whereas PREX favors a large neutron skin thickness in ${}^{208}\mathrm{Pb}$, thereby suggesting a stiff equation of state, CREX suggests instead a much softer equation of state. This discrepancy has caused a large spur in the theoretical community, since no model has been able to simultaneously reproduce within $1\sigma$ the PREX and CREX results. Motivated by a novel correlation between a CREX observable and a combination of bulk symmetry energy parameters, we calibrate three new covariant energy density functionals that reproduce binding energies and charge radii of spherical nuclei—and also accommodate the constraints imposed by PREX and CREX. Given that these models suggest a stiff equation of state at high densities, predictions for neutron star properties are also discussed.

Microscopic cluster model (MCM) is a successful theoretical framework to investigate nuclear clustering phenomena. In this work, we put it in a harmonic oscillator trap (HOT) and propose a new method abbreviated as MCM-HOT to study scattering states of cluster systems in free space. As proofs of concept, we compute the scattering phase shifts for some single-channel two-cluster systems. The numerical results given by MCM-HOT agree well with those from the conventional microscopic $R$-matrix method, implying that our novel method MCM-HOT can be useful in studying scattering processes of light neutron-nucleus systems.

Fusion reactions with stable and radioactive isotopes of light nuclei are indicated to control the crustal composition, nucleosynthesis, and heating mechanism during nuclear burning in neutron stars. The role of isospin asymmetry and proton-/neutron-skin thickness in the fusion excitation function and its related astrophysical $S$ factor is investigated for the reactions involving ${}^{12,14-20,22,24,25,28}\mathrm{O}$ isotopes at sub-barrier energies of astrophysical interest. The calculations are performed in an extended quantum diffusion framework. Among many examined potentials, the only potentials based on the Skyrme-BSk19 and M3Y-Reid nucleon-nucleon interactions successfully reproduce the experimental ${}^{16}\mathrm{O}+{}^{16}\mathrm{O}$, ${}^{12}\mathrm{C}+{}^{16}\mathrm{O}$, ${}^{36}\mathrm{S}+{}^{48}\mathrm{Ca}$, and ${}^{48}\mathrm{Ca}+{}^{48}\mathrm{Ca}$ fusion data, over the whole considered energy range. The height, radius, and curvature of the Coulomb barrier for the interactions involving proton-rich ${}^{12,15}\mathrm{O}$ isotopes are found to impede the near- and above-barrier fusion cross section and the corresponding $S$ factor relative to the ${}^{16}\mathrm{O}+{}^{16}\mathrm{O}$ reaction. However, the relatively small reduced mass and proton-skin thickness act to enhance fusion at deeply sub-barrier energies. For the interactions involving neutron-rich $\mathrm{O}(N>8)$ isotopes, the fusion enhancement due to the produced Coulomb barrier is supported by relatively large $Q$ values and neutron-skin thicknesses, against the increase of reduced masses. The neutron transfer is indicated to hinder the fusion in some ${}^{A_1}\mathrm{O}+{}^{A_2}\mathrm{O}$ $(A_2\ge A_1+4)$ reactions at sub-barrier energy.

Background: Well established coupled channel (CC) and coupled reaction channel (CRC) processes make contributions to the elastic scattering optical model potential (OMP) that are not represented in local density folding models.

Purpose: We aim to establish and characterize the contribution to the ${}^3\mathrm{He}$ and ${}^3\mathrm{H}$ OMPs generated by coupling to proton or neutron pickup and stripping channels, in particular for 33 MeV ${}^3\mathrm{He}$ and ${}^3\mathrm{H}$ OMPs on ${}^{40}\mathrm{Ca}$; also stripping for 40 MeV ${}^3\mathrm{He}$.

Methods: CRC calculations provide the elastic channel $S$ matrix, $S_{lj}$, generated by the included processes. Inversion of $S_{lj}$ then produces a local potential, including a spin-orbit term, that yields, in a single channel calculation, the elastic scattering observables from the CRC calculation. Subtracting the bare potential then gives a local and $l$-independent representation of the dynamical polarization potential, DPP.

Results: Pickup generates greater OMP absorption for ${}^3\mathrm{He}$ than for ${}^3\mathrm{H}$. Neutron stripping for ${}^3\mathrm{H}$ generates much greater absorption than proton stripping for ${}^3\mathrm{He}$. Neutron pickup for ${}^3\mathrm{He}$ has a substantial repulsive effect. All stripping and pickup processes reduce the rms radius of the OMP. None of the coupling effects can be represented by a uniform renormalization of the OMP. A comparison of 33 and 40 MeV ${}^3\mathrm{He}$ stripping yields evidence of energy dependence of DPPs with available data.

Conclusions: The DPPs challenge the notion that local density folding models can provide a satisfactory description of elastic scattering from nuclei. No standard form global OMP could fit precisely ${}^3\mathrm{He}$ or ${}^3\mathrm{H}$ elastic scattering from ${}^{40}\mathrm{Ca}$. For both pickup and stripping coupling, the increase in reaction cross section is much less than the cross section to the coupled channel states, which is the opposite of what was found in many other cases.

We performed a least-squares fit analysis to reproduce the elastic angular distributions for $\alpha$ scattering on various nuclei form ${}^{12}\mathrm{C}$ to ${}^{208}\mathrm{Pb}$ for incident energies in the range 18–70 MeV using a velocity-dependent optical model (VDOM). The model reproduced the experimental data well including the enhanced angular distributions in the large-angle scattering region, which is commonly known as the anomalous large angle scattering (ALAS). Our best-fit potential parameters are linear functions of incident energy. Although the ALAS effect is not present in the case of $\alpha$ scattering on the medium mass ${}^{58}\mathrm{Ni}$ and heavy mass ${}^{208}\mathrm{Pb}$ nuclei, we considered these nuclei to demonstrate the effectiveness of the VDOM in describing the angular distributions for $\alpha$ scattering on various light, medium, and heavy mass nuclei. For $\alpha$ scattering on ${}^{40}\mathrm{Ca}$, we compared our results to two previous works that adopted the conventional optical model. One model reproduced the data better at low energies, while the other performed better at high energies. In contrast, the velocity-dependent model of this work described the data across the considered angular range.

Natural indium targets were exposed to high-energy bremsstrahlung radiation, from 9 MeV to 23 MeV. Using the measured $\gamma$ spectra, the yield ratio of ${}^{113m}\mathrm{In}$ and ${}^{115m}\mathrm{In}$ was determined. It was checked to what extent the measured values of the yield ratio can be reproduced using the existing experimental data of cross sections of relevant photonuclear reactions, as well as cross sections obtained by talys calculations. The measured reaction yield ratio was used to reconstruct the energy differential cross section of ${}^{115}\mathrm{In}(\gamma ,2n){}^{113m}\mathrm{In}$ using the unfolding procedure.

We propose two functions to distinguish fission-like events from quasielastic (QE) scattering and deep-inelastic collisions (DIC), for a better analysis of the measured mass-total kinetic energy distributions of binary fragments formed in fusion-fission reactions. We note that the ratio of capture to DIC events evidently decreases with the decreasing of the depth of the capture pocket predicted from the Skyrme energy density functional with which the capture pocket could be extracted from the measured mass-energy distributions. Together with the improved quantum molecular dynamics simulations, in which the typical contact time of the reaction partners is smaller than 200 $\mathrm{fm/}c$ for QE and is larger than 600 $\mathrm{fm/}c$ for fission-like events, we find that the ratio of capture to touching cross section systematically increases with the pocket depth.

Background: The fission mechanism of sub-lead nuclides remains unclear, especially the types of fission modes involved and their corresponding shell effects.

Purpose: The aim is to identify the different modes in the fission of ${}^{187}\mathrm{Ir}$, and investigate the corresponding mechanism.

Method: The three-dimensional Langevin approach considering nucleus elongation, deformation, and mass asymmetry is applied to simulate fission dynamics. The macro-microscopic models are used to calculate the transport coefficients.

Results: The fragment mass, deformation, and total kinetic energy (TKE) of ${}^{187}\mathrm{Ir}$ fission in the excitation energies range from 30 to 45 MeV are calculated. Based on the mass-TKE correlations, four fission modes are identified, namely two asymmetric standard modes, a symmetric superlong mode, and a symmetric liquid-drop mode. Strong excitation-energy resistance of two asymmetric modes is found. The mass distributions show the dominance of single-peak shape, which is in good agreement with experimental data. The fission potential energy surface and the fission dynamics are analyzed to investigate the origins of the modes and the competition between neutron and proton shell effects.

Conclusions: Multiple fission modes are included in the ${}^{187}\mathrm{Ir}$ fission behind the single-peak-like distribution of observables. The proton and neutron magic numbers with different asymmetry parameter might heighten the sensitivity to the uncertainties of shell corrections.

In this work we investigate the $J/\psi$ production in proton-proton collisions at the center-of-mass energy $\left(\sqrt{s}\right)$ equal to 2.76, 5.02, 7, 8, and 13 TeV with the parton and hadron cascade model PACIAE 2.2a. It is based on PYTHIA but extended considering the partonic and hadronic rescatterings before and after hadronization, respectively. In the PYTHIA sector the $J/\psi$ production quantum chromodynamics processes are selected specially and a bias factor is proposed correspondingly. The calculated total cross sections, the transverse momentum differential, and the rapidity differential cross sections of $J/\psi$ in the forward rapidity region reproduce the corresponding experimental measurements reasonably well. In the mid-rapidity region, the double-differential cross sections at $\sqrt{s}=5.02$, 7, and 13 TeV are also in a good agreement with the experimental data. Moreover, we interpolate the double-differential cross section as well as the total cross section of $J/\psi$ in the mid-rapidity region at $\sqrt{s}=8$ TeV, which could be validated if the experimental data are available.

In inertial confinement fusion implosions, tertiary reaction-in-flight processes create deuterium-tritium fusion reactions $\left[\mathrm{T}{(d,n)}^4\mathrm{He}\right]$ with an incident particle moving at MeV energies instead of the thermonuclear keV temperatures. Additional relativistic kinematic treatments were added to a nuclear resonance code, spect, and resulting calculations showed an upshifting of the deuterium-tritium fusion $\gamma$-ray pathway $\left[\mathrm{T}{(d,\gamma )}^5\mathrm{He}\right]$ for MeV interactions. Using the calculated spectra, a representative reaction-in-flight $\gamma$-ray emission for ICF implosions was estimated.

We extend multireference covariant density-functional theory (MR-CDFT) based on a relativistic point-coupling energy functional to describe the low-lying states of odd-mass nuclei. The nuclear wave function is constructed as a superposition of quadrupole-octupole deformed mean-field configurations, with projection onto angular momentum, particle numbers, and parity within the framework of the generator coordinate method. Using ${}^{25}\mathrm{Mg}$ as an example, we calculate the energy spectrum, electric multipole, and magnetic dipole transition strengths based on three different schemes for the mean-field configurations of odd-mass nuclei. We find that the low-energy structure of ${}^{25}\mathrm{Mg}$ is reasonably reproduced in all three schemes. In particular, the effect of octupole correlation is illustrated in the application to the low-lying parity doublets of ${}^{21}\mathrm{Ne}$. This work demonstrates the success of the MR-CDFT for the low-lying states of odd-mass nuclei with possible strong quadruple-octupole correlations.

Background: We clarified that the fusion hindrance in heavy ion collisions is caused by the expansion of the neck bridge at the early stage of collision [Phys. Rev. C 108, 014612 (2023)]; however, our discussion was limited to the trajectory analysis. To get a reliable fusion cross section, it is important to understand the fusion process connecting with multinucleon transfer and also the process depending on the target orientation in detail. Especially, the effects of target orientation on the multinucleon transfer process have not been discussed so far in our model.

Purpose: First, we investigate precisely the start time of the neck expansion relevant to the mass transfer. The main aims of this paper are to discuss the mass drift in the collision with the different target orientations within the dynamical approach based on the fluctuation-dissipation theorem in the reaction ${}^{36}\mathrm{S}+{}^{232}\mathrm{Th}$.

Method: The orientation effects are incorporated within the framework of the Langevin equation with three nuclear deformation parameters as the degree of freedom and the two-center shell model (TCSM) for the potential energy of the system.

Results: The start time of the neck expansion was presumed to be 10 zs ($\mathrm{zs}={10}^{-21}\mathrm{s}$) by analysis in several entrance channels. By taking account of the target nuclear orientation, a strong mass-angle correlation was obtained which is compatible with the experimental data. There was a large difference in the mass transfer or the mass drift mode in the fusion process between the tip and side collisions.

Conclusions: Not only “delayed relaxation” of the neck but also the nuclear orientation effects have an important role in the strong correlation between fragment mass and its emitting angle. The mass evolution toward mass symmetry is slower than the standard mass drift mode assuming an exponential-type function. Particularly, the mass drift of the tip collision follows the slow mass drift mode assuming a Fermi-type function rather than an exponential-type function, which is related to the different features of the maximum neck cross-sectional area in the sticking process.

Utilizing rapidity-dependent measurements to map the QCD phase diagram provides a complementary approach to traditional beam-energy-dependent measurements around midrapidity. The changing nature of thermodynamic properties of QCD matter along the beam axis in heavy-ion collisions at low collision energies both motivates and poses challenges for this method. In this study, we derive the analytical cumulant-generating function for subsystems within distinct rapidity windows, while accounting for global net-baryon charge conservation of the full system. Rapidity-dependent net-baryon cumulants are then calculated for a system exhibiting inhomogeneity along the beam axis, and their sensitivity to finite acceptances through changing rapidity bin widths is explored. We highlight the nontrivial behaviors exhibited by these cumulants, underscoring their importance in establishing a noncritical baseline for interpreting net-proton cumulants in the search for the QCD critical point. Finally, we discuss the implications of the rapidity scan for mapping the QCD phase diagram within the current context.

It is well known that the traditional treatment of radiative corrections that utilizes the “true” neutrino momentum ${\vec{p}}_{\nu }$ in the differential decay rate formula could lead to a $\sim \alpha /\pi$ systematic error in certain observables due to the mistreatment of 4-body kinematics. I investigate the theory structure of one of the proposed solutions, the “${\nu }^{\prime }$-formalism”, in the nonrecoil limit appropriate for neutron and nuclear $\beta$ decays. I derive an elegant master formula for the 4-body phase space and use it to reanalyze the spectrum-dependent “outer” radiative corrections to the $\beta$ decay of a polarized spin-half nucleus; a complete set of analytic expressions is provided for readers to straightforwardly obtain the final numerical results. I compare it to the “recoil formalism” where the energy of the recoil nucleus is fixed.

Calculations of (anti)neutrino-nucleus scattering cross sections are vital since experimental results for these cross sections for terrestrial-based (anti)neutrino sources in the low-to-intermediate energy ranges are exceedingly rare. A recent measurement of the scattering of stopped-pion neutrinos off ${}^{127}\mathrm{I}$ by the COHERENT Collaboration yielded a cross section that was only $41\%$ of the expected theoretical prediction. Inspired by this, we have computed the cross sections for (anti)neutrino scatterings off ${}^{127}\mathrm{I}$ and ${}^{133}\mathrm{Cs}$ by considering also the effect of the quenching of the weak axial coupling $g_{\text{A}}$ on the results. Two quenching schemes, a conservative and a radical estimate, were considered. The cross sections as functions of the neutrino energy are presented along with folded cross sections for stopped-pion and supernova (anti)neutrino spectra. The nuclear model used was the microscopic quasiparticle-phonon model based on large single-particle model spaces and realistic $G$-matrix-based effective two-body interactions. The obtained inclusive cross sections for stopped-pion neutrino scattering off ${}^{127}\mathrm{I}$ are in good agreement with the experimental results. The results indicate that discrepancy between the experimental and theoretical results could be at least partly explained by the quenching of $g_{\text{A}}$.