arXiv subjects

Ishfaq A. Rather

Publications and source records attributed to Ishfaq A. Rather.

4 recordsLinked to original sources

arXiv2024

Microscopic Investigation of Ground State Properties and Shape Evolution in Osmium Isotopes

The present study focuses on investigating the shape evolution of neutron-rich even-even Osmium (Os) transitional nuclei within the range of neutron number N = 82 to N = 190. The investigation is conducted using density-dependent meson-nucleon and point-coupling models within the framework of the covariant density functional theory (CDFT). Additionally, the results obtained from the CDFT calculations are compared with those obtained using the relativistic mean-field model with a non-linear meson-nucleon interaction. The potential energy curve for Os isotopes (ranging from $^{158}$Os to $^{260}$Os) is analyzed in order to identify phase shape transitions, such as oblate-spherical-prolate. Furthermore, ground state bulk properties are calculated to gain insights into the structure of Os isotopes. The self-consistent calculations reveal a clear shape transition in the even-even Os isotopes, and overall, good agreement is observed among the different models employed as well as with the available experimental data.

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arXiv2023

Radial Oscillations in Neutron Stars with Delta Baryons

We investigate the effect of $Δ$ baryons on the radial oscillations of neutron and hyperon stars, employing a density-dependent relativistic mean-field model. The spin-$3/2$ baryons are described by the Rarita-Schwinger Lagrangian density. The baryon-meson coupling constants for the spin-3/2 decuplet and the spin-1/2 baryonic octet are calculated using a unified approach relying on the fact that the Yukawa couplings present in the Lagrangian density of the mean-field models must be invariant under the SU(3) and SU(6) group transformations. We calculate the 20 lowest eigenfrequencies and corresponding oscillation functions of $Δ$-inclusive nuclear (N+$Δ$) and hyperonic matter (N+H+$Δ$) by solving the Sturm-Liouville boundary value problem and also verifying its validity. We see that the lowest mode frequencies for N+$Δ$ and N+H EoSs are higher as compared to the pure nucleonic matter because of the deltas and hyperons present. Furthermore, the separation between consecutive modes increases with the addition of hyperons and $Δ$s.

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arXiv2023

Magnetic-Field Induced Deformation in Hybrid Stars

The effects of strong magnetic fields on the deconfinement phase transition expected to take place in the interior of massive neutron stars are studied in detail for the first time. For hadronic matter, the very general density-dependent relativistic mean-field (DD-RMF) model is employed, while the simple, but effective vector-enhanced bag model (vBag) model is used to study quark matter. Magnetic-field effects are incorporated into the matter equation of state and in the general-relativity solutions, which also satisfy Maxwell's equations. We find that for large values of magnetic dipole moment, the maximum mass, canonical mass radius, and dimensionless tidal deformability obtained for stars using spherically symmetric Tolman-Oppenheimer-Volkoff (TOV) equations and axisymmetric solutions attained through the LORENE library differ considerably. The deviations depend on the stiffness of the equation of state and on the star mass being analyzed. This points to the fact that, unlike what was assumed previously in the literature, magnetic field thresholds for the approximation of isotropic stars and the acceptable use of TOV equations depend on the matter composition and interactions.

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arXiv2022

Theoretical studies on structural properties and decay modes of $^{284-375}$119 isotopes

In this manuscript, we analyze the structural properties of $Z=119$ superheavy nuclei in the mass range of 284 $\le$ A $\le$ 375 within the framework of axially deformed relativistic mean field theory (RMF) and calculate the binding energy, radii, quadrupole deformation parameter, separation energies and density profile. To investigate the phenomenon of shape coexistence the RMF calculations are performed within three possible solutions i.e. prolate, oblate and spherical configurations. To get a better visualization of nucleon and total matter distribution, two-dimensional contour representation of density distribution for $^{291}$119 and $^{303}$119 has been made. Further, a competition between possible decay modes such as $α-$decay, $β-$decay and spontaneous fission (SF) of the isotopic chain of $Z=119$ superheavy nuclei under study is systematically analyzed within self-consistent relativistic mean field model. Our analysis confirmed that $α-$decay is restricted within the mass range 284 $\leq$ A $\leq$ 296 and thus being the dominant decay channel in this mass range. There is no possibility of $β-$decay for the considered isotopic chain. In addition, we forecasted the $α-$decay chain of fission survival nuclides i.e. $^{284-296}$119 and found as one $α$ chain from $^{284}$119 and $^{296}$119, two consistent $α$ chains from $^{285}$119 and $^{295}$119, three consistent $α$ chains from $^{286}$119 and $^{294}$119, four consistent alpha chains from $^{287}$119, six consistent alpha chains from $^{288-293}$119. Thus, such studies can be of great significance to the experimentalists in very near future for synthesizing $Z=119$ superheavy nuclei.

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