arXiv subjects

Subhrajyoti Biswas

Publications and source records attributed to Subhrajyoti Biswas.

10 recordsLinked to original sources

arXiv2019

Effect of in-medium $π$ and $η$ propagators to charge symmetry breaking interaction

We revisit the charge symmetry breaking $(CSB)$ in nucleon-nucleon $(NN)$ interaction caused by $π$-$η$ mixing in nuclear matter $(NM)$ employing one boson exchange $(OBE)$ model. The medium effect on $CSB$ is incorporated through the in-medium $π$ and $η$ propagators. In addition, the medium modification to the nucleon mass is also taken into account to construct the $CSB$ class $III$ potential considering off-shell $π$-$η$ mixing amplitude and large contribution of in-medium meson propagators to $CSB$ potential is found for the pseudoscalar $(PS)$ interaction compared to that of pseudovector $(PV)$ interaction.

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arXiv2016

Pionic dispersion relations in the presence of a weak magnetic field

In this work, dispersion relations of $π^0$ and $π^{\pm}$ have been studied in vacuum in the limit of weak external magnetic field using a phenomenological pion-nucleon $(πN)$ Lagrangian. For our purpose, we have calculated the results up to one loop order in self energy diagrams with the pseudoscalar $(PS)$ and pseudovector $(PV)$ pion-nucleon interactions. By assuming weak external magnetic field it is seen that the effective mass of pion gets explicit magnetic field dependence and it is modified significantly for the case of PS coupling. However, for the PV coupling, only a modest increase in the effective mass is observed. These modified dispersion relations due to the presence of the external field can have substantial influence in the phenomenological aspect of the mesons both in the context of neutron stars as well as relativistic heavy ion collisions.

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arXiv2010

$π$-$η$ mixing and charge symmetry violating NN potential in matter

We construct density dependent Class $III$ charge symmetry violating (CSV) potential due to mixing of $π$-$η$ meson with off-shell corrections. The density dependence enters through the non-vanishing $π$-$η$ mixing driven by both the neutron-proton mass difference and their asymmetric density distribution. The contribution of density dependent CSV potential is found to be appreciably larger than the contribution of vacuum CSV potential.

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arXiv2009

Matter induced charge symmetry violating NN potential

We construct density dependent Class $III$ charge symmetry violating (CSV) potential due to mixing of $ρ$-$ω$ meson with off-shell corrections. Here in addition to the usual vacuum contribution, the matter induced mixing of $ρ$-$ω$ is also included. It is observed that the contribution of density dependent CSV potential is comparable to that of the vacuum contribution.

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arXiv2009

Ground state energy of spin polarized quark matter with correlation

We calculate the ground state energy of cold and dense spin polarized quark matter with corrections due to correlation energy $(E_{corr})$. Expressions for $E_{corr}$ both in the non-relativistic and ultra-relativistic regimes have been derived and compared with the exchange and kinetic term present in the perturbation series. It is observed that the inclusion of correlation energy does not rule out the possibility of the ferromagnetic phase transition at low density within the model proposed by Tatsumi\cite{tatsumi00}. We also derive the spin stiffness constant in the high density limit of such a spin polarized matter.

hep-ph↗

arXiv2009

Spin dependent Fermi Liquid parameters and properties of polarized quark matter

We calculate the spin dependent Fermi liquid parameters (FLPs), single particle energies and energy densities of various spin states of polarized quark matter. The expressions for the incompressibility($K$) and sound velocity ($c_1$) in terms of the spin dependent FLPs and polarization parameter $(ξ)$ are derived. Estimated values of $K$ and $c_1$ reveal that the equation of state (EOS) of the polarized matter is stiffer than the unpolarized one. Finally we investigate the possibility of the spin polarization (ferromagnetism) phase transition.

hep-ph↗

arXiv2008

$ρ$-$ω$ mixing and spin dependent CSV potential

We construct the charge symmetry violating (CSV) nucleon-nucleon potential induced by the $ρ^0$-$ø$ mixing due to the neutron-proton mass difference driven by the $NN$ loop. Analytical expression for for the two-body CSV potential is presented containing both the central and non- central $NN$ interaction. We show that the $ρ$$NN$ tensor interaction can significantly enhance the charge symmetry violating $NN$ interaction even if momentum dependent off-shell $ρ^0$-$ω$ mixing amplitude is considered. It is also shown that the inclusion of form factors removes the divergence arising out of the contact interaction. Consequently, we see that the precise size of the computed scattering length difference depends on how the short range aspects of the CSV potential are treated.

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arXiv2008

Fermi Liquid parameters for dense nuclear matter in Effective Chiral Model

We calculate relativistic Fermi liquid parameters (RFLPs) for the description of the properties of dense nuclear matter (DNM) using Effective Chiral Model. Analytical expressions of Fermi liquid parameters (FLPs) are presented both for the direct and exchange contributions. We present a comparative study of perturbative calculation with mean field (MF) results. Moreover we go beyond the MF so as to estimate the pionic contribution to the FLPs. Finally, we use these parameters to estimate some of the bulk quantities like incompressibility, sound velocity, symmetry energy etc. for DNM interacting via exchange of $σ$, $ω$ and $π$ meson. In addition, we also calculate the energy densities and the binding energy curve for the nuclear matter. Results for the latter have been found to be consistent with two loop calculations reported recently within the same model.

hep-ph↗

arXiv2008

Effects of Dirac sea on pion propagation in asymmetric nuclear matter

We study pion propagation in asymmetric nuclear matter (ANM). One of the interesting consequences of pion propagation in ANM is the mode splitting for the different charged states of pions. First we describe the pion-nucleon dynamics using the non-chiral model where one starts with pseudoscalar (PS) $π$N coupling and the pseudovector (PV) representation is obtained via suitable non-linear field transformations. For both of these cases the effect of the Dirac sea is estimated. Subsequently, we present results using the chiral effective Lagrangian where the short-distance behavior (Dirac vacuum) is included by re-defining the field parameters as done in the modern effective field theory approach developed recently. The results are compared with the previous calculations for the case of symmetric nuclear matter (SNM). Closed form analytical results are presented for the effective pion masses and dispersion relations by making hard nucleon loop (HNL) approximation and suitable density expansion.

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arXiv2006

Isospin mode splitting and mixing in asymmetric nuclear matter

We estimate exclusive density and asymmetry parameter dependent dispersion relations of various charged states of pions in asymmetric nuclear matter. The possibility of matter induced mixing of $π^0$ with $η$ is clearly exposed with the further mass modification of $π^0$ meson due to mixing. Asymmetry driven mass splitting and mixing amplitude are of the same order as the corresponding values in vacuum. Closed form analytic results for the mass shifts and dispersion relations with and without mixing are presented. Furthermore, we discuss the sensitivity of our results on the scalar mean field within the framework of Quantum Hadrodynamics.

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