We propose a new model of a {\it gravastar} admitting conformal motion. While retaining the framework of the Mazur-Mottola model, the gravastar is assumed to be internally charged, with an exterior defined by a Reissner-Nordstr{\"o}m rather than a Schwarzschild line element. The solutions obtained involve (i) the interior region, (ii) the shell, and (iii) the exterior region of the sphere. Of these three cases the first case is of primary interest since the total gravitational mass vanishes for vanishing charge and turns the total gravitational mass into an {\it electromagnetic mass} under certain conditions. This suggests that the interior de Sitter vacuum of a charged gravastar is essentially an electromagnetic mass model that must generate the gravitational mass. We have also analyzed various other aspects such as the stress energy tensor in the thin shell and the entropy of the system.Comment: Minor addition, Accepted in Phys. Lett.

This paper discusses a new type of thin-shell wormhole constructed by applying the cut-and-paste technique to two copies of a charged black hole in generalized dilaton-axion gravity, which was inspired by low-energy string theory. After analyzing various aspects of this thin-shell wormhole, we discuss its stability to linearized spherically symmetric perturbations.PACS numbers: 95.30. Sf, 95.36.+x, 04.20.Jb

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A variational Monte Carlo study of 4 H (0 + ) and 4 H * (1 + ) hypernuclear states using a realistic Hamiltonian and a fully correlated wavefunction including N space-exchange correlation (SEC) is presented. For the strange sector of the Hamiltonian, phenomenological charge symmetric N and NN potentials are used along with Argonne NN(AV18) and Urbana NNN(UIX) potentials for the non-strange sector. Complete energy breakdown, -separation energy, polarization of the nuclear core, nucleon radii ( r 2 p 1/2 and r 2 n 1/2 ) and nucleon and density profiles are calculated for the 4 H hypernuclear state. The 0 + -1 + energy splitting and complete energy breakdown for 1 + excited state is also calculated. For the exact assessment of charge symmetry breaking energy, Coulomb energies for the rearranged distributions of protons in 4 He hypernucleus are calculated. Results for all these physical observables both with and without SEC in the wavefunction are essential to extract SEC effects. Best set of variational parameters of optimized wavefunctions, both with and without SEC, are found. Dependence of results on various sets of N potential strengths is investigated. This leads to some interesting results. Nucleons are pushed towards periphery as well as towards centre by the hyperon which stays in the interior region most of the time. SEC effects are found to be significant. Nuclear core is found to be compact having more polarization energy with SEC in the wavefunction.

The signature inversion observed in rotational bands belonging to high-j configurations of odd–odd deformed nuclei has been analyzed within the framework of an axially symmetric rotor plus two-particle model. The Coriolis and n–p interaction are considered the main cause of energy staggering. However, γ-triaxial deformation and the numbers of valence protons, Np, and neutrons, Nn also contribute to the energy staggering between odd- and even-spin states.