International Journal of Modern Physics E

The 2023 update of the discovery of nuclide project is presented when 13 nuclides were observed for the first time. In addition, a major update and revision of the isotope discovery project is described.

Essential understanding about the structure of rotating nuclei has come from the study on the band crossings which are often associated with the alignment of a pair of quasiparticles. In this work, the first and second discontinuities in the low-lying rotational bands of ${}^{156-160}$Er nuclei have been investigated systematically, for the first time, within the paired cranked Nilsson–Strutinsky–Bogoliubov (CNSB) framework. Our calculations show these irregularities are related to the high-j intruder $i_{13/2}$ neutron and $h_{11/2}$ proton alignment, which is consistent with the previous studies within the cranked shell model (CSM) approach. A comparison was made with the experimental data where available, and good agreement is observed.

We investigate the effect of a weak magnetic field on momentum transport in a thermal QCD medium at finite quark chemical potential using a semiclassical kinetic theory. In the presence of a magnetic field, the momentum transport coefficients acquire a tensor structure, reflected by the five shear (${\eta }_0,{\eta }_1,{\eta }_2,{\eta }_3$ and ${\eta }_4$) and two bulk viscous components (${\zeta }_0$ and ${\zeta }_1$). The weak magnetic field removes the degeneracy in the effective mass of flavors, leading to different masses for the left-handed (L) and right-handed (R) chiral modes of quarks. The coefficients, ${\eta }_0,{\eta }_1$ and ${\eta }_3$ decrease with magnetic field in L mode and increase in $\mathrm{\text{R}}$ mode, whereas, ${\eta }_2$ and ${\eta }_4$ increase in both L and $\mathrm{\text{R}}$ modes. The bulk viscous coefficients, ${\zeta }_0$ and ${\zeta }_1$ increase with magnetic field for both L and R modes. The shear and bulk viscous coefficients positively amplify with baryon asymmetry.

It has become obvious that one crucial aspect in understanding high energy nuclear reactions is the fragmentation of colliding nuclei. The nuclear emulsion is a 4$\pi$ detector that makes it simple to identify and quantify the charges of projectile fragments. In this work, we study the multiplicity distribution and angle distributions of single, double charge projectile fragments, fast target protons (gray particle) as well as their correlation for the events produced in the interactions of ${}^{84}{\mathrm{\text{Kr}}}_{36}$ with emulsion nuclei at 1AGeV. We also study the target-dependent angle distribution of gray particles. The results are compared with other experimental data as per availability. This analysis shows that multiplicity distributions have a remarkable link between the projectile and target fragmentation processes.

Orbital-free density functional theory (DFT) is much more efficient than the orbital-dependent Kohn–Sham DFT due to the avoidance of the auxiliary one-body orbitals. The machine learning approach has been applied to build nuclear orbital-free DFT recently [Wu et al., Phys. Rev. C 105 (2022) L031303] and achieved more precise descriptions for nuclei than existing orbital-free DFTs. Here, improved machine learning nuclear orbital-free density functional is built by including the Thomas–Fermi approach as a basement. Performances of the functional are compared in detail with the ones based on the pure machine learning approach. It is found that with the Thomas–Fermi functional included, the machine-learning-based functional can achieve better performance in directly predicting the kinetic energies and in providing the ground-state properties by the self-consistent procedures.

This study is an investigation of the effect of the pairing strength using different types of pairing (surface, volume and mixed surface–volume pairing) on the ground state properties of even and odd Mg isotopes. The Hartree–Fock–Bogoliubov (HFB) theory and two types of Skyrme forces, SKI3 and SLY6, were employed in our calculations. The pairing strength values are modified at each execution of the HFBTHO code to obtain the experimental values of binding energy for the investigated even and odd isotopes separately. Then a new formula for pairing strength for each even and odd isotope independently for all the pairing, surface, volume and mixed surface–volume types is developed by fitting the pairing strength values to the mass number. Based on the newly generated formulas for pairing strength, some of the calculated ground state properties are found to depend strongly on the pairing strength values and the pairing type also plays an essential role in providing accurate results.

In this paper, considering the power of the daughter nuclear charge as a function of the orbital angular momentum taken away by the emitted proton, we propose a formula for the half-life of proton radioactivity. In this formula, we have three coefficients with orbital angular momentum dependence. Using experimentally measured half-lives for 8 proton emitters with $l=0$, 14 proton emitters with $l=2$ and 18 proton emitters with $l=5$, we have obtained the coefficients. The root mean square deviations of our formula respect to the experimental value are found 0.2514, 0.4442 and 0.1846 for emitters $l=0$, 2 and 5, respectively. We have compared our results with Sreeja formula, the semiempirical relation of Hatsukawa and theoretical models such as the Coulomb and proximity potential model (CPPM) and the Gamow-like model. The better agreement with experimental data was observed for our formula in comparison with other theoretical models and Sreeja and Hatsukawa formulas.

In the framework of free triaxiality model, branching ratio of reduced E2-transitions probabilities is studied for the full region changes of the triaxiality parameter. The variables of quadrupole deformations ${\beta }_2$ and $\gamma$ are dynamic. The Davidson potential for ${\beta }_2$ and $\gamma$ variables was used. In the free triaxiality model, the energy levels were obtained by taking into account the high-order terms of the rotational energy operator series, which lead energy levels of ground-state-band, $\beta$- and $\gamma$-bands to improve considerably the agreement of the results with experimental data. The quadrupole moment of the nucleus expressed in terms of two internal quadrupole moments: $Q_0$ is quadrupole moment about the symmetry axis, $Q_2$ is the measure of the shape asymmetry about the symmetry axis. The intra/inter-band reduced E2-transition probabilities’ ground-state-band, $\beta$- and $\gamma$-bands are presented and are expressed in terms of four parameters: ${\mu }_{{\beta }_2}$, ${\mu }_{\gamma }$, ${\gamma }_0$ and $Q_0$. The influence of $\gamma$-oscillations to the reduced probabilities of E2-transitions is taken into account numerically. The sensitivity of the intra-/inter-band reduced E2-transition probabilities to the triaxiality parameter was analyzed.