S. K. Tripathy

Neutron?proton effective mass splitting and thermal evolution in neutron-rich matter

The thermal evolution of properties of neutron rich asymmetric nuclear matter such as entropy density, internal energy density, free energy density and pressure are studied in the non-relativistic mean field theory using finite range effective interactions. In this framework the thermal evolution of nuclear matter properties is directly connected to the neutron and proton effective mass properties. Depending on the magnitude of neutron-proton effective mass splittings, two distinct behaviours in the thermal evolution of nuclear matter properties are noticed.The thermal evolution of properties of neutron-rich asymmetric nuclear matter such as entropy density, internal energy density, free energy density and pressure is studied in the non-relativistic mean field theory using finite range effective interactions. In this framework, the thermal evolution of nuclear matter properties is directly connected to the neutron and proton effective mass properties. Depending on the magnitude of neutron–proton effective mass splittings, two distinct behaviours in the thermal evolution of nuclear matter properties are noticed.

Proton radioactivity with a Yukawa effective interaction

The half-lives of proton radioactivity of proton emitters are investigated theoretically. Proton-nucleus interaction potentials are obtained by folding the densities of the daughter nuclei with a finite-range effective nucleon-nucleon interaction having Yukawa form. The Wood-Saxon density distributions for the nuclei used in calculating the nuclear as well as the Coulomb interaction potentials are predictions of the interaction. The quantum mechanical tunneling probability is calculated within the WKB framework. These calculations provide reasonable estimates for the observed proton radioactivity lifetimes. The effects of neutron-proton effective mass splitting in neutron-rich asymmetric matter as well as the nuclear matter incompressibility on the decay probability are investigated.

Temperature dependence of the nuclear symmetry energy and equation of state of charge neutral n + p + e + μ matter in beta equilibrium

The temperature and density dependence of the nuclear symmetry energy is studied in the nonrelativistic mean field theory by using a density-dependent finite range effective interaction. The temperature evolution of the interaction part of symmetry energy is decided by the nature of the finite range exchange interactions acting between a pair of like and unlike nucleons, an area which is less understood. In view of this, two cases corresponding to different strengths of exchange interaction between two like nucleons are considered to examine their influence on the temperature dependence of the nuclear symmetry energy. The symmetry energy obtained as a function of temperature and density is used to study the temperature dependence of leptonic fractions, proton fraction and equation of state of charge neutral n + p + e + μ matter under β-equilibrium for the two different cases.

Proton radioactivity half-lives with Skyrme interactions

The potential barrier impeding the spontaneous emission of protons in the proton radioactive nuclei is calculated as the sum of nuclear, Coulomb and centrifugal contributions. The nuclear part of the proton-nucleus interaction potential is obtained in the energy density formalism using the Skyrme effective interaction that results into a simple algebraic expression. The half-lives of the proton emitters are calculated for the different Skyrme sets within the improved WKB framework. The results are found to be in reasonable agreement with the earlier results obtained for more complicated calculations involving finite-range interactions.

Anisotropic cosmological model with variable G and Λ

Anisotropic Bianchi-III cosmological model is investigated with variable gravitational and cosmological constants in the framework of Einstein’s general relativity. The shear scalar is considered to be proportional to the expansion scalar. The dynamics of the anisotropic universe with variable G and Λ are discussed. Without assuming any specific forms for Λ and the metric potentials, we have tried to extract the time variation of G and Λ from the anisotropic model. The extracted G and Λ are in conformity with the present day observations. Basing upon the observational limits, the behavior and range of the effective equation of state parameter are discussed.

An effective Nuclear Model: from Nuclear Matter to Finite Nuclei

The momentum and density dependence of mean fields in symmetric and asymmetric nuclear matter are analysed using the simple density dependent finite range effective interaction containing a single Gaussian term alongwith the zero-range terms. Within the formalism developed, it is possible to reproduce the various diverging predictions on the momentum and density dependence of isovector part of the mean field in asymmetric matter. The finite nucleus calculation is formulated for the simple Gaussian interaction in the framework of quasilocal density functional theory. The prediction of energies and charge radii of the interaction for the spherical nuclei compares well with the results of other effective theories.

Azimuthal correlations of D-mesons in p+p and p+Pb collisions at LHC energies

Abstract.We study the correlations of D mesons produced in p+p and p+Pb collisions. These are found to be sensitive to the effects of the cold nuclear medium and the transverse momentum (

A Model Study of D-h Azimuthal Correlation at LHC Energies

p_{{\rm T}}

Density dependence of nuclear symmetry energy

pT) regions we are looking into. In order to put this on a quantitative footing, as a first step we analyse the azimuthal correlations of D meson-charged hadron (Dh), and then predict the same for D meson-anti D meson (

Bulk viscous string cosmological models with electromagnetic field

{\rm D}\overline{{\rm D}}