arXiv subjects

Pallabi Parui

Publications and source records attributed to Pallabi Parui.

10 recordsLinked to original sources

arXiv2025

Compressibility and speed of sound in magnetized nuclear matter with broken scale invariance

The thermodynamical properties of magnetized nuclear matter at finite temperature and baryon chemical potential are studied within an effective model incorporating the QCD trace anomaly effect. The presence of magnetic field induces anisotropic structure in the energy momentum tensor due to the broken rotational invariance. The study exhibits a phase transition through the sudden change of the effective nucleon mass in a certain range of baryon chemical potential and temperature. The addition of nucleonic vacuum contribution at finite magnetic field leads to the magnetic catalysis effect. The change in squared speed of sound with chemical potential at various temperatures is closely connected to the nature of phase transition in nuclear matter. The pressure anisotropy results in different values of sound speed and isothermal compressibility in the parallel and perpendicular directions with respect to the magnetic field. The smaller values of isothermal compressibility in the parallel direction compared to the perpendicular one indicate that the equation of state is stiffer along the magnetic field direction. The studies of these thermodynamic observables can have significant importance in analyzing the properties of some compact astrophysical objects as well as in the context of non-central heavy ion collision experiments.

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arXiv2023

Spectral properties of $\omega$, $\rho$ and $A_1$ mesons in hot magnetized matter: effects of (inverse) magnetic catalysis

In-medium masses of the light vector $\omega$, $\rho$ and axial-vector $A_1$ mesons are studied in the magnetized hot nuclear matter, accounting for the effects of (inverse) magnetic catalysis. The in-medium partial decay widths for the $A_1\rightarrow \rho \pi$ channels are studied from the in-medium masses of the initial and the final state particles, by applying a phenomenological Lagrangian to account for the $A_1\rho\pi$ interaction vertices. The masses are calculated within the QCD sum rule framework, with the medium effects coming through the light quark ($\sim \langle \bar{q}q \rangle$) and the scalar gluon condensates ($\sim \langle G^2 \rangle$), as well as the light four-quark condensate ($\sim \langle \bar{q}q\rangle^2 $). The condensates are calculated within the chiral $SU(3)$ model in terms of the medium modified scalar fields: isoscalar $\sigma$, $\zeta$, isovector $\delta$ and the dilaton field $\chi$. The effects of magnetic fields are incorporated through the magnetized Dirac sea contribution as well as the Landau energy levels of protons. The incorporation of the magnetic field through the Dirac sea of nucleons lead to an enhancement (reduction) of the light quark condensates with magnetic field, give rise to the phenomenon of magnetic (inverse) catalysis. The effects of (inverse) magnetic catalysis at finite temperature nuclear matter are studied on the spectral functions and production cross-sections of the neutral $\rho$ and $A_1$ mesons. This may affect the production of the light vector and axial-vector mesons in the peripheral heavy-ion collision experiments, where estimated magnetic field is very large at the early stages of collisions with very high temperature.

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arXiv2022

Medium modifications of Heavy Quarkonia masses in a generalized Linear Sigma Model

We study the mass shifts of the charmonium ($\bar{c}c$) states ($J/ψ$, $ψ(2S)$, $ψ(1D)$, $χ_{c0}$, $χ_{c1}$ and $χ_{c2}$) as well as the bottomonium ($\bar{b}b$) states ($Υ(1S)$, $Υ(2S)$, $Υ_2(1D)$, $χ_{b0}$, $χ_{b1}$ and $χ_{b2}$) in isospin asymmetric nuclear matter. These are investigated using a generalized linear sigma model. The broken scale invariance of QCD is incorporated in the chiral $SU(2)\times SU(2)$ Lagrangian through an effective potential involving logarithmic terms of a scalar (glueball) dilaton field $χ$. The mass shifts of the quarkonium states are obtained through the medium modifications of the dilaton field which simulates the scalar gluon condensate of QCD. We observe an appreciable mass drop in the states of heavy quarkonia under this study. The in-medium masses at finite densities thus obtained should modify the in-medium partial decay widths of heavy quarkonia to open heavy flavor mesons. These density effects can be probed in in the high energy nuclear collisions at the future facility at GSI (at Germany) and JINR (at Russia) in the experiments producing highly dense baryonic matter.

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arXiv2022

In-medium properties of light vector and axial-vector mesons: effects of Dirac sea

The in-medium masses of the light vector, $ρ^{0, \pm}$, $ω$ and the light axial-vector, $A_1^{0, \pm}$ mesons, are studied in the magnetized nuclear matter, accounting for the effects of the Dirac sea. The in-medium partial decay widths for the $A_1\rightarrow ρπ$ channels, are studied from the in-medium masses of the initial and the final state particles, by applying a phenomenological Lagrangian to account for the $A_1ρπ$ interaction vertices. The masses calculated within the QCD sum rule framework, are obtained in terms of the light quark ($\sim \langle \bar{q}q \rangle$) and the scalar gluon condensates ($\sim \langle G^2 \rangle$), as well as the light four-quark condensate ($\sim \langle \bar{q}q\rangle^2 $). The condensates are calculated within the chiral $SU(3)$ model in terms of the medium modified scalar fields. The effects of magnetic fields are incorporated through the Landau energy levels of protons, anomalous magnetic moments (AMMs) of the nucleons in the nuclear matter, in addition to the magnetized Dirac sea contribution, within the chiral effective model. The enhancement (reduction) of the light quark condensates with magnetic field, is called (inverse) magnetic catalysis. The effects of magnetic fields on the in-medium hadronic decay widths of the $A_1$ mesons, are observed to be significant through the Dirac sea effect, accounting for the AMMs of the nucleons. This may affect the light mesons production in the non-central, heavy-ion collision experiments, where estimated magnetic field is very large.

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arXiv2022

Charm mesons in magnetized nuclear matter -- effects of (inverse) magnetic catalysis

We investigate the in-medium masses of the pseudoscalar $(D,{\bar D},D_s^{\pm})$, and vector $(D^*,\bar{D}^*, D_s^{*\pm})$, open charm mesons in isospin asymmetric magnetized nuclear matter, accounting for the effects of Dirac sea. The masses are used to study the in-medium partial decay widths of $D^* \rightarrow D \pi$ ($\bar{D}^*\rightarrow \bar{D}\pi$) and $\Psi(3770) \rightarrow D \bar{D}$, using the $^3P_0$ model. The in-medium masses of the open charm mesons are calculated from their interactions with the nucleons and scalar mesons within the generalized chiral effective model, in terms of the scalar and number densities of nucleons and the scalar fields fluctuations. The effects of Landau energy levels of protons and AMMs of the nucleons are also considered in the magnetized nuclear matter. The light quark condensates are modified considerably with magnetic field, leading to (inverse) magnetic catalysis due to the magnetized Dirac sea effects. The magnetic field causes modifications to occur due to the mixing of the pseudoscalar and longitudinal component of the vector mesons, along with the lowest Landau level contribution to the ground state energy of the charged mesons as point particle correction. For the charmonium state $\Psi(3770)$, the effects of the magnetized Dirac sea are incorporated to the mass modifications through the medium modified scalar dilaton field $\chi$ within the chiral model. The in-medium masses and decay widths of the open charm and charmonium mesons thus obtained should have important observable consequences in the production of the open charm mesons and charmonia in peripheral ultra-relativistic heavy ion collision experiments, where huge magnetic fields are expected to be created.

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arXiv2022

Open bottom mesons in magnetized matter -- effects of (inverse) magnetic catalysis

In-medium masses of the pseudoscalar and vector open bottom mesons ($B$, $\bar{B}$, $B_s$ and $B^*$, $\bar{B}^*$, $B_s^*$) are studied in the magnetized nuclear matter by considering the effects of Dirac sea, within the chiral effective model. The mass modifications arise due to the interactions of the open bottom mesons with the nucleons and the scalar mesons, calculated in terms of the scalar and number densities of the nucleons and the scalar fields fluctuations. The effects of the magnetized Dirac sea lead to the considerable changes in the scalar fields with magnetic field, which are related to the light quark condensates. There is observed to be a (reduction) enhancement in the light quark condensates with magnetic field, a phenomenon called (inverse) magnetic catalysis.The contribution of the magnetic field on the Fermi sea of nucleons are taken into account through the Landau energy levels of protons and anomalous magnetic moments (AMMs) of the nucleons. The additional contribution of the lowest Landau level for the charged mesons are considered. The spin-magnetic field interaction between the longitudinal component of the vector and the pseudoscalar mesons ($B^{*||}(\bar{B}^{*||})-B (\bar{B}))$ and ($B_s^{*||}-B_s$) are studied, which lead to a level repulsion between their masses with magnetic field. Magnetic fields are observed to have significant contribution on the in-medium masses of the open bottom mesons through the Dirac sea effect as comparedto the case when this effect is not considered. In vacuum, considerable changes are obtained only due to the magnetized Dirac sea at zero and finite nucleonic AMMs.

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arXiv2022

QCD sum rule analysis of Heavy Quarkonium states in magnetized matter -- effects of (inverse) magnetic catalysis

The masses of the $1S$ and $1P$ states of heavy quarkonia are investigated in the magnetized, asymmetric nuclear medium, accounting for the Dirac sea effects, using a combined approach of chiral effective model and QCD sum rule method. These are calculated from the in-medium scalar and twist-2 gluon condensates, calculated within the chiral model. The gluon condensate is simulated through the scalar dilaton field, $\chi$ introduced in the model through a scale-invariance breaking logarithmic potential. Considering the scalar fields to be classical, the dilaton field, $\chi$, the non-strange isoscalar, $\sigma (\sim (\langle \bar u u\rangle +\langle \bar d d\rangle ))$, strange isoscalar, $\zeta (\sim \langle \bar s s\rangle)$ and non-strange isovector, $\delta (\sim (\langle\bar u u\rangle-\langle\bar d d\rangle)$) fields, are obtained by solving their coupled equations of motion, as derived from the chiral model Lagrangian. The effects of magnetic field due to the Dirac sea as well as the Landau energy levels of protons, and the non-zero anomalous magnetic moments of the nucleons are considered in the present study. In presence of an external magnetic field, there is also mixing between the longitudinal component of the vector meson and pseudoscalar meson (PV mixing) in both quarkonia sectors, leading to a rise (drop) of the masses of $J/\psi^{||}\ (\eta_c$) and $\Upsilon^{||}(1S)\ (\eta_b$) states. These might show in the experimental observables, e.g., the dilepton spectra in the non-central, ultra-relativistic heavy ion collision experiments at RHIC and LHC, where the produced magnetic field is huge.

hep-ph↗

arXiv2021

QCD sum rule analysis of Bottomonium ground states

The in-medium masses of the bottomonium ground states [$1S$ ($Υ(1S), η_b$) and $1P$ ($χ_{b0},χ_{b1}$)] are investigated in the magnetized vacuum (nuclear medium), using the QCD sum rule framework. In QCD sum rule approach, the mass modifications are calculated in terms of the medium modifications of the scalar and twist-2 gluon condensates, which are obtained in the nuclear medium, from the medium change of a scalar dilaton field, $χ$ within a chiral effective model. The in-medium masses of the bottomonium ground states are observed to decrease with increasing density. P-wave states are observed to have more appreciable mass-shifts than the S-wave states. In the present investigation, the effects of spin-mixing between 1S bottomonium states, $Υ(1S)$ and $η_b$ are taking into account in presence of an external magnetic field. The contribution of magnetic fields are seen to be dominant via spin-magnetic field interaction effects, which leads to an appreciable rise and drop in the in-medium masses of the longitudinal component of vector $1S$ state ($Υ$) and pseudoscalar state ($η_b$) respectively. For zero magnetic field, the effects of baryon density on the bottomonium ground states in isospin asymmetric nuclear medium are observed to be quite appreciable. These should have observable consequences for the production of the open and hidden bottom meson states resulting from high energy asymmetric nuclear collisions in facilities which probe high density baryonic matter. There is observed to be large contributions to the masses of the longitudinal component of the vector bottomonium state, $Υ(1S)$ and pesudoscalar state $η_b$ in strong magnetic fields.

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arXiv2019

Charmonium ground states in presence of strong magnetic fields

The in-medium masses of the lowest S-wave charmonium states (vector meson, $J/ψ$ and pseudoscalar meson, $η_c$) and P-wave charmonium states (scalar, $χ_{c0}$ and axialvector $χ_{c1}$) are investigated in magnetized nuclear matter, within the framework of QCD sum rule approach. These are computed from the medium modifications of the scalar as well as twist--2 gluon condensates, obtained from the medium modifications of a scalar dilaton field, within a chiral effective model. The effects of the magnetic field, isospin asymmetry and density on the masses of these charmonium states have been investigated. The modifications of the masses of the P-wave charmonium states ($χ_{c0}$ and $χ_{c1}$) are observed to be much larger as compared to those of the S-wave states, $J/ψ$ and $η_c$ within the QCD sum rule approach. The effects of the coupling of the spin with the magnetic field are also investigated in the present work, which result in the mixing of the spin zero charmonium state with the longitudinal component of the vector meson. This leads to an increase (drop) in mass of the longitudinal $J/ψ$ ($η_c$) for the S-wave states. The effects of the spin-magnetic field interactions are observed to be dominant at high magnetic fields.

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arXiv2019

Light vector mesons ($ω$, $ρ$ and $ϕ$) in strong magnetic fields: A QCD sum rule approach

The mass modifications of the light vector mesons ($ω$, $ρ$ and $ϕ$) are investigated in asymmetric nuclear matter in the presence of strong magnetic fields, using a QCD sum rule approach. These are computed from the medium modifications of the non-strange and strange light quark condensates as well as scalar gluon condensate. The quark and gluon condensates are calculated from the medium changes of the scalar fields (non-strange and strange) and a scalar dilaton field in the magnetized nuclear matter, within a chiral SU(3) model. The scalar dilaton field within the model breaks the scale invariance of QCD and simulates the gluon condensate. The anomalous magnetic moments for the nucleons are taken into account in the present study.

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