arXiv subjects

T. K. Jha

Publications and source records attributed to T. K. Jha.

27 records · Page 2Linked to original sources

arXiv2009

`$f_0 (600)$' and chiral dynamics

The role of light scalar meson `$f_0 (600)$' is investigated in nuclear matter in an Effective chiral model in the mean-field approach. For the purpose, we scan the properties of the matter at various saturation densities imposing constraint such as the vacuum value of the pion decay constant $f_π \approx 131 ~MeV$. With a simple approach, the bound on the mass of the scalar meson is calculated and found in the range $m_σ = 546 \pm 10 MeV$. Further, the present analysis show that nuclear matter favor high nucleon effective mass and dominant repulsive forces at high density, the insight and the implications of which are discussed.

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arXiv2009

Axially-symmetric Neutron stars: Implication of rapid rotation

Models of relativistic rotating neutron star composed of hyperon rich matter is constructed in the framework of an effective field theory in the mean-field approach. The gross properties of compact star is calculated at both static and the mass-shedding limit in the axially symmetric basis. The effect of appearance and abundance of hyperons on equation of state of dense matter and stellar properties is lineated with particular emphasis on the underlying nuclear interactions. We find that the models can explain fast rotations, which supports the existence of millisecond pulsars. An important offshoot of the present investigation is that, irrespective of the model parameters and interaction taken, the star seems to sustain faster rotations (an increase in rotational frequency up to $\approx$ 50%) without any further deformation.

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arXiv2009

From nuclear matter to Neutron Stars

Neutron stars are the most dense objects in the observable Universe and conventionally one uses nuclear theory to obtain the equation of state (EOS) of dense hadronic matter and the global properties of these stars. In this work, we review various aspects of nuclear matter within an effective Chiral model and interlink fundamental quantities both from nuclear saturation as well as vacuum properties and correlate it with the star properties.

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arXiv2009

Constraints on nuclear matter parameters of an Effective Chiral Model

Within an effective non-linear chiral model, we evaluate nuclear matter parameters exploiting the uncertainties in the nuclear saturation properties. The model is sternly constrained with minimal free parameters, which display the interlink between nuclear incompressibility ($K$), the nucleon effective mass ($m^{\star}$), the pion decay constant ($f_π$) and the $σ-$meson mass ($m_σ$). The best fit among the various parameter set is then extracted and employed to study the resulting Equation of state (EOS). Further, we also discuss the consequences of imposing constraints on nuclear EOS from Heavy-Ion collision and other phenomenological model predictions.

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arXiv2008

On attributes of a Rotating Neutron star with a Hyperon core

We study the effect of rotation on global properties of neutron star with a hyperon core in an effective chiral model with varying nucleon effective mass within a mean field approach. The resulting gross properties of the rotating compact star sequences are then compared and analyzed with other theoretical predictions and observations from neutron stars. The maximum mass of the compact star predicted by the model lies in the range $(1.4-2.4) ~M_{\odot}$ at Kepler frequency $Ω_K$, which is consistant with recent observation of high mass stars thereby reflecting the sensitivity of the underlying nucleon effective mass in the dense matter EoS. We also discuss the implications of the experimental constraints from the flow data from heavy-ion collisions on the global properties of the rotating neutron stars.

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arXiv2007

Neutron star matter in an effective model

We study the equation of state (EOS) for dense matter in the core of the compact star with hyperons and calculate the star structure in an effective model in the mean field approach. With varying incompressibility and effective nucleon mass, we analyse the resulting EOS with hyperons in beta equilibrium and its underlying effect on the gross properties of the compact star sequences. The results obtained in our analysis are compared with predictions of other theoretical models and observations. The maximum mass of the compact star lies in the range $1.21-1.96 ~M_{\odot}$ for the different EOS obtained, in the model.

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arXiv2004

The island of deformation and shape co-existence in neutron-deficient nuclei of the Pb region using relativistic mean field model

We have investigated the ground-state structures of even-even neutron-deficient isotopes of Hg and Pb nuclei within the framework of a deformed relativistic mean field formalism for a number of commonly used parameter sets, namely NL1, NL3, NL-SH, NL-RA1 and TM1. The ground states of a bunch of Hg and Pb-isotopes towards the proton-dripline are found to be deformed for all the forces, with a constant pairing gap. The small differences in the ground- and the first-excited state binding energies predict a sea of low-lying excited states, and hence of shape co-existence, for both the Hg and Pb nuclei. In general, a discrepancy between the experimentally observed and theoretically predicted (sign of) quadrupole deformations is noticed in this mass region. The constrained potential energy surfaces and the single-particle energy spectra analyzed for some selected nuclei show that the known large shell gap for Pb nuclei at Z=82 is almost extinguished for its proton-rich isotopes.

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arXiv2003

Hot Nuclear Matter in Asymmetry Chiral Sigma Model

In the frame work of SU(2) chiral sigma model, the nuclear matter properties at zero and finite temperature have been investigated. We have analyzed the nuclear matter equation of state by varying different parameters, which agrees well with the one derived from the heavy-ion collision experiment at extreme densities and reliable realistic(DBHF) model at low density region. We have then calculated the temperature dependent asymmetric nuclear matter, also investigated the critical temperature of liquid gas phase transition and compared with the experimental data. We found that the critical temperature in our model is in the range of 14-20 MeV.

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arXiv2003

Role of BCS-type pairing in light deformed nuclei: A relativistic mean field approach

We calculate the binding energy and deformation parameter for light nuclei with and without pairing using a deformed relativistic mean field model. The role of BCS-type pairing effect is analyzed for Ne and F isotopes. The calculated odd-even staggering and the deformation parameters argue strongly against the role of pairing in the light nuclei.

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