Shashi K. Dhiman

A study of Λ hypernuclei within the Skyrme–Hartree–Fock model

Abstract We investigate the properties of the single Λ hypernuclei within a Skyrme–Hartree–Fock (SHF) model. The parameters of the Skyrme type effective lambda–nucleon ( ΛN ) interaction are obtained by fitting to the experimental Λ binding energies of hypernuclei with masses spanning a wide range of the periodic table. Alternative parameter sets are also obtained by omitting nuclei below mass number 16 from the fitting procedure. The SHF calculations are performed for the binding energies of the Λ single-particle states over a full mass range using the best fit parameter sets obtained in these fitting procedures and the results are compared with the available experimental data. The data show some sensitivity to the parameter sets obtained with or without including the nuclei below mass 16. The radii of the Λ orbits in the hypernuclear ground states and the Λ effective mass in nuclear matter show some dependence on different parameter sets. We present results for the total binding energy per baryon of the hypernuclei over a large mass region to elucidate their stability as a function of the baryon number. We have also employed the our best fit ΛN parameter sets to investigate the role of hyperons in some key properties of neutron stars.

Nonrotating and rotating neutron stars in the extended field theoretical model

We study the properties of nonrotating and rotating neutron stars for a new set of equations of state (EOSs) with different high-density behavior obtained using the extended field theoretical model. The high-density behavior for these EOSs are varied by varying the {omega}-meson self-coupling and hyperon-meson couplings in such a way that the quality of fit to the bulk nuclear observables, nuclear matter incompressibility coefficient, and hyperon-nucleon potential depths remain practically unaffected. We find that the largest value for maximum mass for the nonrotating neutron star is 2.1M{sub {center_dot}}. The radius for a neutron star with canonical mass is 12.8-14.1 km, provided only those EOSs are considered for which the maximum mass is larger than 1.6M{sub {center_dot}}, the lower bound on the maximum mass measured so far. Our results for the very recently discovered fastest rotating neutron star indicate that this star is supramassive with mass 1.7M{sub {center_dot}}-2.7M{sub {center_dot}} and circumferential equatorial radius 12-19 km.

Temperature and density dependence of asymmetric nuclear matter and protoneutron star properties within an extended relativistic mean field model

The effect of temperature and density dependence of the asymmetric nuclear matter properties is studied within the extended relativistic mean field (ERMF) model, which includes the contribution from the self and mixed interaction terms by using different parametrizations obtained by varying the neutron skin thickness

Double-Λ hypernuclei within a Skyrme–Hartree–Fock approach

\Delta

Structure of

r and

^8

\omega

B and astrophysical

-meson self-coupling (

S_{17}

\zeta

factor

). We observed that the symmetry energy and its slope and incompressibility coefficients decrease with increasing temperatures up to saturation densities. The ERMF parametrizations were employed to obtain a new set of equations of state (EOS) of the protoneutron star (PNS) with and without inclusion of hyperons. In our calculations, in comparison with cold compact stars, we obtained that the gravitational mass of the protoneutron star with and without hyperons increased by

Exploring the extended density-dependent Skyrme effective forces for normal and isospin-rich nuclei to neutron stars

\sim 0.4M_{\odot}