International Journal of Modern Physics E

The properties of charmed mesons in nuclear matter and nuclei are reviewed. Different frameworks are discussed paying a special attention to unitarized coupled-channel approaches which incorporate heavy-quark spin symmetry. Several charmed baryon states with negative parity are generated dynamically by the s-wave interaction between pseudoscalar and vector meson multiplets with 1/2⁺ and 3/2⁺ baryons. These states are compared to experimental data. Moreover, the properties of open-charm mesons in matter are analyzed. The in-medium solution accounts for Pauli blocking effects, and for the meson self-energies in a self-consistent manner. The behavior in the nuclear medium of the rich spectrum of dynamically-generated baryon states is studied as well as their influence in the self-energy and, hence, the spectral function of open charm. The possible experimental signatures of the in-medium properties of open charm are finally addressed, such as the formation of charmed nuclei, in connection with the future FAIR facility.

A review is given of attempts to describe nuclear properties in terms of neutron–proton pairs that are subsequently replaced by bosons. Some of the standard approaches with low-spin pairs are recalled but the emphasis is on a recently proposed framework with pairs of neutrons and protons with aligned angular momentum. The analysis is carried out for general j and applied to N=Z nuclei in the 1f_7/2 and 1g_9/2 shells.

We study systematically various types of phase transitions in nuclear matter at finite temperature T and baryon chemical potential μ based on the extended linear sigma model with nucleon degrees of freedom. It is shown that there are three types of phase transitions in nuclear matter: the chiral symmetry nonrestoration (SNR) at high temperature, the well-known liquid–gas (LG) phase transition at sub-saturation density and the Lifshitz phase transition (LPT) from the fully-gapped state to the state with Fermi surface. Their phase diagrams are established in the (T, μ)-plane and their physical properties are investigated in detail. The relationship between the chiral phase transition and the LG phase transition in nuclear matter is discussed.

The transition scenario between bound, virtual and resonance states is investigated for the Dirac and Schrödinger operator with a spherically symmetric square well potential of varying depth λ≥0. This includes rigorous results derived with the help of the Birman–Schwinger principle and perturbation methods, and a numerical study of the motion of the corresponding S-matrix poles as a function of λ by displaying the computed energy curves in the complex plane.

We study the half-lives of some nuclei via the alpha-decay process in ground-state to ground-state (g.s.→g.s.) transitions. To go through the problem, we consider the parabola and WKB approximations to fin the penetration probability. This new formula is used to evaluate alpha-decay half-lives and a good agreement with the experiment is obtained.

The alpha-decay half-lives of the 24 isotopes of Eu (Z = 63) nuclei in the region 130≤A≤153, have been studied systematically within the Coulomb and proximity potential model (CPPM). We have modified the assault frequency and re-determined the half-lives and they show a better agreement with the experimental value. We have also done calculations on the half-lives within the recently proposed Coulomb and proximity potential model for deformed nuclei (CPPMDN). The computed half-lives are compared with the experimental data and they are in good agreement. Using our model, we could also demonstrate the influence of the neutron shell closure at N = 82, in both parent and daughter nuclei, on the alpha-decay half-lives.

Using the Coulomb modified Glauber model, we analyze the elastic scattering of protons from He and Li isotopes at 60 MeV and 72 MeV. The calculations require two inputs; the nucleon–nucleon (NN) amplitude and the nucleon density distributions in target nuclei. The central part of the NN amplitude is taken from the available NN scattering observables. To find the spin-dependent part, we employ p-⁴He scattering data to fix its parameter values. For target nuclei, we use nucleon density distributions available in the literature. The NN amplitude, as obtained in this work, is then used to study the sensitivity of the calculated differential cross-section and polarization for p-^{6, 8}He scattering on the density distributions used. It is found that both the differential cross-section and polarization could provide a test to know which is the better choice of nucleon (especially neutron) density distributions. We also present the differential cross-sections for p-^{6, 9, 11}Li scattering at 60 MeV and 72 MeV in order to assess the suitability of the obtained NN amplitude. It is found that the results are in reasonable agreement with the experiment up to only moderate scattering angles, leaving significant discrepancy at large scattering angles. Our calculations suggest the need of medium modifications in the NN amplitude, arising due to Pauli blocking.

Using one- and two-body density matrices, we calculate the spatial and momentum distributions, two-particle Hanbury-Brown–Twiss (HBT) correlation functions, and the chaotic parameter λ in HBT interferometry for the systems of boson gas within the harmonic oscillator potentials with anisotropic frequencies in transverse and longitudinal directions. The HBT chaotic parameter, which can be obtained by measuring the correlation functions at zero relative momentum of the particle pair, is related to the degree of Bose–Einstein condensation and thus the system environment. We investigate the effects of system temperature, particle number and the average momentum of the particle pair on the chaotic parameter. The value of λ decreases with the condensed fraction, f₀. It is one for f₀ = 0 and zero for f₀ = 1. For a certain f₀ between 0 and 1, we find that λ increases with the average momentum of the particle pair and decreases with the particle number of system. The results of λ are sensitive to the ratio, ν = ω_z/ω_ρ, of the frequencies in longitudinal and transverse directions. They are smaller for larger ν when ω_ρ is fixed. In the heavy-ion collisions at the Large Hadron Collider (LHC) energy the large identical pion multiplicity may possibly lead to a considerable Bose–Einstein condensation. Its effect on the chaotic parameter in two-pion interferometry is worth considering in earnest.

Optical potentials for the scattering of K^± from ⁶Li and ¹²C nuclei are calculated using the Watanabe superposition model in terms of the alpha-particle and deuteron optical potentials. The elastic and inelastic scattering differential cross-sections obtained using these potentials are compared with experimental data. Good fits are obtained without modifying any of the parameters. Further measurements for K^± scattering from ⁶Li are stressed.

Adopting the equation of states (EOSs) from the relativistic mean field (RMF) theory, the relationships among the keplerian frequency f_K, gravitational mass M and radius R for the rapidly rotating neutron stars with and without hyperons are presented and analyzed. For various RMF EOSs, the empirical formula , proposed by P. Haensel et al. [Astron. Astrophys.502 (2009) 605], is found to be an approximation with the error at most 13% and such approximation is worse for the neutron stars with hyperons. It indicates that the errors should be considered when the empirical formula is used to discuss the properties of neutron stars.

In this study, the elastic scattering of ⁶He projectile from ¹²⁰Sn nucleus has been analyzed in terms of optical model (OM). Microscopic double folding (DF) model has been used to generate the real central part of the OM potential. The imaginary part has been restricted to Woods–Saxon phenomenological form. Skyrme–Hartree–Fock, Symmetrized Fermi and Gaussian-Exponential densities for ⁶He nucleus while Hartree–Fock–Bogolyubov (HFB) density of ¹²⁰Sn nucleus have been used to construct the real DF potential. For the effective interaction, the widely used M3Y has been adopted in the DF procedure. The results of DF have been compared with both literature experimental data and phenomenological analysis.