A data-driven idea is presented to test if light nuclei and hypernuclei obey the coalescence-inspired sum rule, i.e., to test if the flow of a light nucleus or hypernucleus is the summed flow of each of its constituents. Here, the mass difference and charge difference among the constituents of light nuclei and hypernuclei are treated appropriately. The idea is applied to the available data for $\sqrt{s_{NN}}=3$ GeV fixed-target $\mathrm{Au}+\mathrm{Au}$ collisions at the Relativistic Heavy Ion Collider (RHIC), published by the STAR Collaboration. It is found that the sum rule for light nuclei is approximately valid near midrapidity ($-0.3<y<0$), but there is a clear violation of the sum rule at large rapidity ($y<-0.3$). The Jet AA Microscopic Transport Model (JAM), with baryonic mean-field plus nucleon coalescence, generates a similar pattern as obtained from the experimental data. In the present approach, the rapidity dependence of directed flow of the hypernuclei ${}_{\mathrm{\Lambda }}^3\mathrm{H}$ and ${}_{\mathrm{\Lambda }}^4\mathrm{H}$ is predicted in a model-independent way for $\sqrt{s_{NN}}=3$ GeV $\mathrm{Au}+\mathrm{Au}$ collisions, which will be explored by ongoing and future measurements from STAR.

Regression analysis for the symmetry energy within a sample of relativistic mean-field models of nuclear matter is performed. The selected models consistently meet the experimentally obtained limitations. A proposed measure of the importance of adding the fourth-order term to the symmetry energy is analyzed. As a result of the research, it became possible to arrange the models and perform two-dimensional and one-dimensional linear regression analyses. The one-dimensional regression analysis between the input parameters confirms the appropriateness of introducing the division of the sample of considered models into four separate classes representing four statistically different fits. An additional result is the formulation of constraints on the function, which describes the energy density of the system. The performed two-dimensional regression analysis refers to an alternative method of parametrizing the symmetry energy using the power law. It was found that the Akaike information criterion of model selection involving the $\gamma$ exponent is sensitive to splitting the symmetry energy into the kinetic and potential parts. The analysis indicates that the more appropriate way of splitting is the one that does not consider the interaction with the sigma meson in the kinetic part.

Motivated by the recent observation of high-mass pulsars ($M\approx 2M_{\odot }$), we employ the $\sigma$-cut potential on the equation of state (EOS) of high-density matter and the properties of neutron stars within the relativistic mean-field model using ${\text{TM1}}^{*}$ parameter set. The $\sigma$-cut potential is known to reduce the contributions of the $\sigma$ field, resulting in a stiffer EOS at high densities and hence leading to larger neutron star masses without affecting the properties of nuclear matter at normal saturation density. We also analyzed the effect of the same on pure neutron matter and also on the neutron star matter with and without hyperonic core and compared it with the available theoretical, experimental, and observational data. The corresponding tidal deformability (${\mathrm{\Lambda }}_{1.4}$) is also calculated. With the choice of meson-hyperon coupling fixed to hypernuclear potentials, we obtain $\approx 10\%$ increase in mass by employing the $\sigma \text{−}\mathrm{cut}$ potential for $f_s=0.6$. Our results are in good agreement with various experimental constraints and observational data, particularly with the GW170817 data.

Nuclear fission produces fragments whose spins are coupled to the relative angular motion via angular momentum conservation. It is shown how ensembles of such spins can readily be obtained by either direct microcanonical sampling or by sampling of the associated normal modes of rotation. The resulting distribution of the spin-spin opening angle is illustrated in various three- and two-dimensional scenarios and it is demonstrated how recent mutually conflicting model calculations can be well reproduced with different assumptions about the scission geometry.

Nuclear $\beta$-decay half-lives are predicted with the so-called gross theory, which is improved by including the spin-orbit splitting from relativistic Hartree-Bogoliubov theory. The calculated differences between the Gamow-Teller and Fermi transition energies are in excellent agreement with experimental data for Zr, Sn, and Pb isotopes. The influences of the $Q$ value and the integrated Fermi function on the calculations of $\beta$-decay half-lives are carefully studied. Based on the mass predictions of the latest Weizsäcker-Skyrme model, the half-lives from Ca to Pb isotopes are systematically calculated. It is found that the Weizsäcker-Skyrme model well reproduces the experimental data with accuracy better than that of quasiparticle random-phase approximation approaches. When extrapolated to the unknown region, our results are generally close to those from the Skyrme finite-amplitude method. This improved gross theory can be employed to calculate half-lives based on mass predictions of various models and hence can provide relatively consistent half-life inputs for the $r$-process studies.

We study the implications of isospin symmetry in nuclear systems on two-body distributions and derive relations between different densities or momentum distributions of a given nucleus or of different nuclei in the same isospin multiplet. A connection between neutrinoless double beta decay transition of mirror nuclei and two-body densities is also obtained. The relations are numerically verified by means of quantum Monte Carlo calculations. We discuss the relevance of these results to the analysis of nuclear short-range correlations and also show that isospin symmetry allows us to extract information about the spectator nucleons when a short-range correlated pair is formed.

The Wigner rotation matrix ($d$ function), which appears as a part of the angular-momentum-projection operator, plays a crucial role in modern nuclear-structure models. However, it is a longstanding problem that its numerical evaluation suffers from serious errors and instability, which hinders precise calculations for nuclear high-spin states. Recently, Tajima [Phys. Rev. C 91, 014320 (2015)] has made a significant step toward solving the problem by suggesting the high-precision Fourier method, which however relies on formula-manipulation softwares. In this paper we propose an effective and efficient algorithm for the Wigner $d$ function based on the Jacobi polynomials. We compare our method with the conventional Wigner method and the Tajima Fourier method through some testing calculations, and demonstrate that our algorithm can always give stable results with similar high-precision as the Fourier method, and in some cases (for special sets of $j,m,k$, and $\theta$) ours are even more accurate. Moreover, our method is self-contained and less memory consuming. By taking the ${}^{156}\mathrm{Dy}$ yrast band as an example, we show that with the $d$ function calculated by our proposed Jacobi method in the angular-momentum projector, the realistic projected-shell-model calculation can be aggressively extended to the high-spin region where the conventional Wigner method collapses completely. A related testing code and subroutines for the three algorithms of $d$ function are provided as Supplemental Material in the present paper.

We generalize to N2LO Skyrme functionals the semiclassical approach of Grammaticos and Voros in order to calculate the extended Thomas-Fermi expressions of the new densities and currents appearing at the N2LO level. Within a one-dimensional model of semi-infinite symmetric nuclear matter and using a simple Fermi-like density profile, we obtain an easy-to-use formula for the surface-energy coefficient including the contributions of the central, density-dependent, and spin-orbit terms up to ${\hslash }^2$. Such a formula can be easily used as a first attempt to constrain the surface properties of new N2LO Skyrme parametrizations. The N2LO parametrization tested in this paper is shown to exhibit a shift (compared with a full Hartree-Fock calculation) which is quantitatively similar to the one obtained with the traditional Skyrme parametrizations.

Background: The information about the pre-scission emitted neutrons is crucial for the fission dynamics study such as fission time scale and dissipation mechanism.

Purpose: The aim is to investigate the influence of the pre-scission neutron emission on the fragments mass, total kinetic energy, and the deformation distribution at the scission point in ${}^{238}\mathrm{U}(n,f)$ fissions at 110, 325, and 500 MeV.

Method: A three-dimensional Langevin approach considering nucleus elongation, deformation, and mass asymmetry is applied to simulate fission dynamics. The Hauser-Feshbach statistical decay model is coupled to simulate the pre-scission neutron emission.

Results: The properties of the pre-scission emitted neutron are first investigated. It is found that the multiplicity and the average kinetic energy increase with increasing excitation energy. The energy carried away by neutron emission is not negligible and it leads to the multichance fission, especially for the 110 MeV case. The fragments mass, total kinetic energy, and the deformation distribution at the scission point are then calculated with and without coupling the Hauser-Feshbach statistical decay model. It is found that the calculations partially reproduce the leftward shift of the experimental fragment mass distribution at high excitation energy. The pre-scission neutron emission also causes a reduction of the average total kinetic energy by about 2 MeV and a leftward shift of the distribution. The deformation distribution shows that about 75% of the fragments are produced in spherical and prolate ellipsoid shapes. No significant influence on deformation at the scission point was found.

Conclusions: For high-energy fission, the energy reduction by pre-scission neutron emission should be considered, which will lead to the multichance fission. The pre-scission neutron emission is one of the reasons for the decrease of the average mass and the leftward shift of the fission fragments mass and total kinetic energy distribution.

Within the framework of intermittency analysis, a search for critical fluctuations is ongoing to locate the possible critical point in the quantum chromodynamics phase diagram. In this study, self-similar critical fluctuations from a critical Monte Carlo (CMC) model have been incorporated into the cascade ultrarelativistic quantum molecular dynamics (UrQMD) model. This hybrid $\mathrm{UrQMD}+\mathrm{CMC}$ model exhibits a clear power-law behavior of scaled factorial moment for charged particles in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=7.7$–200 GeV. By comparing the $\mathrm{UrQMD}+\mathrm{CMC}$ model results with those from the STAR experiment, it is found that the value of a calculated scaling exponent falls in the range of the experimental measurement when 1–2 % signal of intermittency fluctuations is added into the UrQMD sample.

The half-lives of two-proton $\left(2p\right)$ emitters ${}^6\mathrm{Be}$, ${}^{12}\mathrm{O}$, ${}^{16}\mathrm{Ne}$, ${}^{19}\mathrm{Mg}$, ${}^{45}\mathrm{Fe}$, ${}^{48}\mathrm{Ni}$, ${}^{54}\mathrm{Zn}$, and ${}^{67}\mathrm{Kr}$ have been predicted using the Coulomb and proximity potential model for deformed nuclei (CPPMDN) incorporating ground-state deformation (${\beta }_2$) and orientation effect, and the predicted values are compared with experimental data. As predicted values are in agreement with experimental data I extended my studies to 51 nuclei, whose decay are energetically possible with released energy $Q_{2p}>0$ for which $2p$ radioactivity is not yet experimentally detected, and the predicted half-life values are compared with other theoretical models/formulas. I hope the future experimental investigations will be guided by these predictions. The new Geiger Nuttall plot connecting ${log}_{10}\left[T_{1/2}\left(s\right)\right]$ computed using the CPPMDN versus $[Z_d^{0.8}+{\ell }^{\beta }]Q_{2p}^{-1/2}$ is found to be linear which shows the reliability of my calculations. It is found for the first time that $2p$ radioactivity also obeys the linear nature of a universal curve connecting ${log}_{10}\left[T_{1/2}\left(s\right)\right]$ versus $-lnP$ as that of the proton, $\alpha$, and cluster radioactivity.

Background: The determination of the nuclear neutron properties suffers from uncontrolled uncertainties, which have attracted considerable attention recently, such as in the context of the PREX experiment.

Purpose: Our aim is to analyze the sensitivity of charge-exchange $(p,n)$ reactions to the neutron density distribution ${\rho }_n$ and constrain the neutron characteristics in the nuclear structure models.

Method: By combing the folding and the mean-field models, the nucleon-nucleus $\left(NA\right)$ potential can be obtained from the nuclear density distribution. Further, the $(p,p)$ and $(p,n)$ cross sections for ${}^{48}\mathrm{Ca}$ and ${}^{208}\mathrm{Pb}$ are calculated following the distorted-wave Born approximation method.

Results: Compared with the $(p,p)$ cross section, the effects of ${\rho }_n$ variation on the $(p,n)$ cross section are significant, which is due to the impact of isovector properties. Based on the global folding model analyses of data, it is found that ${}^{48}\mathrm{Ca}$ and ${}^{208}\mathrm{Pb}$ have relatively large neutron skin thickness $\mathrm{\Delta }{R}_{np}$.

Conclusions: Results illustrate that the charge-exchange $(p,n)$ reaction is a sensitive probe of ${\rho }_n$. The results in this paper can offer useful guides for future experiments of neutron characteristics.

We describe and implement a procedure for determining the couplings of a relativistic mean-field theory (RMFT) that is optimized for application to neutron star phenomenology. In the standard RMFT approach, the couplings are constrained by comparing the theory's predictions for symmetric matter at saturation density with measured nuclear properties. The theory is then applied to neutron stars which consist of neutron-rich matter at densities ranging up to several times saturation density, which allows for additional astrophysical constraints. In our approach, rather than using the RMFT to extrapolate from symmetric to neutron-rich matter and from finite-sized nuclei to uniform matter, we fit the RMFT to properties of uniform pure neutron matter obtained from chiral effective field theory. Chiral effective field theory incorporates the experimental data for nuclei in the framework of a controlled expansion for nuclear forces valid at nuclear densities and enables us to account for theoretical uncertainties when fitting the RMFT. We construct four simple RMFTs that span the uncertainties provided by chiral effective field theory for neutron matter, and are consistent with current astrophysical constraints on the equation of state. Our RMFTs can be used to model the properties of neutron-rich matter across the vast range of densities and temperatures encountered in neutron stars and their mergers.

The $\alpha$ clustering in ${}^{10}\mathrm{Be}$ and ${}^{12}\mathrm{Be}$ has been studied within the framework of the real-time evolution method (REM). By using the effective interaction tuned to reproduce the charge radii and the threshold energies, we have evaluated the $\alpha$ reduced width amplitude (RWA) and spectroscopic factor ($S$ factor) for the ground and excited states. With several improvements made in this work, comparing with our previous calculations, larger rates of clustering results are obtained for ${}^{10}\mathrm{Be}$ and ${}^{12}\mathrm{Be}$ with correct asymptotics at large distance.

We introduce the concept of the nuclear octupole fourfold (i.e., applying simultaneously to all the four octupole deformations ${\alpha }_{30}$, ${\alpha }_{31}$, ${\alpha }_{32}$, and ${\alpha }_{33}$) neutron “magic number” $N=196$ and discuss the physical consequences of its presence. Our theoretical predictions are obtained using the realistic phenomenological mean-field approach with the deformed Woods-Saxon potential, the latter employing the new parametrization optimized in our preceding articles. Correlations among 4 parameters in the set of 12 parameters of the Woods-Saxon potential are detected and removed employing Monte Carlo approach leading to stabilization of the predictive power of the modeling. Our main focus is examining the impact of the four-fold octupole magic number $N=196$ on the stability properties of superheavy nuclei with $114\le Z\le 130$ and $166\le N\le 206$. Calculations suggest that majority of the examined nuclei are either spherical or octupole deformed, octupole-tetrahedral geometry playing the dominating role lowering the ground-state energy by up to 8 MeV. The origin and manifestations of this domination are illustrated and discussed. It turns out that, in several cases, alternative point-group symmetries may lead to noticeable lowering of the nuclear energy; this concerns the $C_{2v}$ geometry associated with ${\alpha }_{31}$, the $D_{3h}$ geometry related to ${\alpha }_{33}$, and $D_{2d}$ corresponding to the combination of ${\alpha }_{32}$ and ${\alpha }_{20}$ quadrupole component.

The nuclear level density (NLD) and $\gamma$-ray strength function ($\gamma \mathrm{SF}$) of ${}^{63}\mathrm{Ni}$ have been investigated using the Oslo method. The extracted NLD is compared with previous measurements using particle evaporation and those found from neutron resonance spacing. The $\gamma \mathrm{SF}$ was found to feature a strong low-energy enhancement that could be explained as $M1$ strength based on large-scale shell model calculations. Comparison of $\gamma \mathrm{SFs}$ measured with the Oslo method for various $\mathrm{Ni}$ isotopes reveals systematic changes to the strength below $5\mathrm{MeV}$ with increasing mass.

A new Hamiltonian is established for the particle nuclei near ${}^{132}\mathrm{Sn}$ by including both core excitations and neutron intruder orbit $i_{13/2}$. In this Hamiltonian, the two-body force strengths and monopole terms are determined by the data in ${}^{133}\mathrm{Sn}$, ${}^{134}\mathrm{Sn}$, ${}^{133}\mathrm{Sb},{}^{134}\mathrm{Sb}$, ${}^{134}\mathrm{Te}$, ${}^{135}\mathrm{Te}$, and ${}^{135}\mathrm{I}$. According to this interaction, the level spectra and electromagnetic transitions are described well in the model space including six proton orbits ($0g_{9/2},0g_{7/2},1d_{5/2},1d_{3/2},2s_{1/2},0h_{11/2}$), and eight neutron orbits ($1d_{3/2},0h_{11/2},1f_{7/2},2p_{3/2},2p_{1/2},0h_{9/2},1f_{5/2},0i_{13/2}$). This work shows that the neutron intruder orbit $i_{13/2}$ is necessary to describe particle nuclei near ${}^{132}\mathrm{Sn}$. The configuration including orbit $i_{13/2}$ forms a spin-trap structure and wins the competition of the lowest states at level $13/2^{+}$ in ${}^{137,139}\mathrm{Te}$. Spin-trap structures are also existed in levels $2^{-}$ and $9^{-}$ in ${}^{136,138}\mathrm{Te}$. Due to the decay block by spin-trap structures, these states are predicted as good isomers.

The Peierls-Yoccoz (PY) rotational energy of nuclei has been analyzed by the angular-momentum projection on the axial Hartree-Fock solutions, by using the semi-realistic effective Hamiltonian M3Y-P6. The rotational energy is decomposed into contributions of the individual terms of the Hamiltonian, and their ratios to the total PY rotational energy are calculated. Except for light or weakly deformed nuclei, the ratios of the individual terms of the Hamiltonian are insensitive to nuclides and deformation. The contributions of kinetic energies are large and close to the rigid-rotor values, although those of central forces are sizable. For light or weakly deformed nuclei, the ratios significantly depend on nuclei and deformation. The contributions of noncentral forces are not negligible. Regardless of nuclides, the attractive forces decrease the moment of inertia, and the repulsive forces increase it. A general formula for the PY rotational energy is derived, which suggests that higher-order terms of the cumulant expansion play roles in the rotational energy and the moment of inertia for light or weakly deformed nuclei.

Based on the transport model isospin-dependent Boltzmann-Uehling-Uhlenbeck coupled with a phase-space coalescence afterburner, we studied the effects of the high-momentum tail (HMT) of nucleon momentum distribution in initialization in ${}^{197}\mathrm{Au}+{}^{197}\mathrm{Au}$ reactions at a beam energy of 400 MeV/nucleon with different impact parameters. We found remarkable impact parameter-dependent HMT effects on the fragment multiplicity distribution. The average neutron to proton ratio of produced isotopes is also affected by the HMT. The rapidity distributions of triton and ${}^3\mathrm{He}$ and their elliptic flows are all evidently affected by the HMT. All the effects of the HMT on the cluster production in heavy-ion collisions are centrality dependent.

Fluorine is one of the most interesting elements in nuclear astrophysics. The ${}^{19}\mathrm{F}(p,\alpha ){}^{16}\mathrm{O}$ reaction is of astrophysical importance in addressing fluorine abundances in the universe and CNO material loss in the first generation stars. As a day-1 campaign in the Jinping Underground Nuclear Astrophysics experiment facility (JUNA), we report the full direct measurement results of the ${}^{19}\mathrm{F}(p,\alpha \gamma ){}^{16}\mathrm{O}$ reaction, which is one of the important channels in the ${}^{19}\mathrm{F}(p,\alpha ){}^{16}\mathrm{O}$ reaction. The $\gamma$-ray yields were measured over a center-of-mass energy range of $E_{\mathrm{c}.\mathrm{m}.}$ = 72.4–344 keV, covering the astrophysical Gamow window. The measurement has reached down to an unprecedentedly low energy of 72.4 keV. The experiment was performed under the extremely low cosmic-ray-induced background environment of the China JinPing underground Laboratory (CJPL), one of the deepest underground laboratories in the world (2400 m). The astrophysical $S$ factors in the energy region of 72.4–188.8 keV have been derived experimentally for the first time. The present low-energy astrophysical $S$ factors deviate significantly from previous theoretical predictions, and the associated uncertainties are remarkably reduced. The thermonuclear ${}^{19}\mathrm{F}(p,\alpha \gamma ){}^{16}\mathrm{O}$ rate has been determined down to a low temperature of $\approx 0.05$ GK, for astrophysical modeling, based on a firmer experimental basis. Furthermore, the present work shows that the contribution owing to the ($p,{\alpha }_0$) channel dominates the total ($p,\alpha$) rate over the entire low temperature region below 0.12 GK, clarifying the role these two channels contributing to the total rate.