International Journal of Modern Physics E最新文献

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. C105 (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.

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 1$$A$$GeV. 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.

It is known that pseudospin symmetry plays a crucial role in formation of many physical phenomena. By combining the relativistic mean field theory with the complex momentum representation method, the pseudospin symmetry in the single particle resonant states in the deformed nucleus ${}^{154}$Dy is investigated through the energy and width splittings, the quadrupole deformation parameter, the radial density distributions and occupation probabilities of the pseudospin doublets. Near the continuum threshold, the pseudospin symmetry is well reserved in both bound and resonant states. The energy and width splittings of pseudospin doublets in resonant states exhibit correlations with the deformation and quantum numbers. The good pseudospin symmetry is expected with lower pseudo-orbital angular momentum projection $\tilde{\mathrm{\Lambda }}$ and the main quantum number N. In general, an increase in deformation tends to weaken the quality of the pseudospin symmetry. The understanding of the evolution of the pseudospin doublets in the resonant states has been deepened by studying the pseudospin symmetry in the deformed nuclei.

To resolve the nonconvex optimization problem in partial wave analysis, this paper introduces a novel approach that incorporates fraction constraints into the likelihood function. This method offers significant improvements in the efficiency of pole searching within partial wave analysis.

The ⁷He nucleus was studied using the ⁶He${(d,p)}^7$He reaction in inverse kinematics at 29 $\text{A}\cdot$MeV ⁶He beam delivered by the ACCULINNA-2 fragment separator (FLNR, JINR). The registration of neutrons from ${}^7\mathrm{\text{He}}\to n{+}^6\mathrm{\text{He}}$ decay made it possible to derive the ⁷He ground state parameters, the decay energy of 0.38(2)$$MeV and width of 0.11(3)$$MeV.

We calculate four types of initial vorticities in Au$$$+$$$Au collisions at energies $\sqrt{S_{\mathrm{\text{NN}}}}=5$–200$$GeV using a microscopic transport model PACIAE. Our simulation shows the nonmonotonic dependence of the initial vorticities on the collision energies. The energy turning point is around 10–15$$GeV for different vorticities but not sensitive to impact parameter.