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Sarthak Satapathy

Publications and source records attributed to Sarthak Satapathy.

18 recordsLinked to original sources
arXiv2026

One-loop HDL thermodynamics of a strongly magnetized isospin asymmetric cold quark matter

We have computed the longitudinal pressure and magnetization of strongly magnetized cold QCD matter in the presence of both quark and isospin chemical potentials using the hard-dense-loop perturbation theory (HDLpt). For that purpose, we have first obtained the resummed quark and gluon propagators in the presence of a strong magnetic field and isospin density. We have found that pressure gets monotonically enhanced with both chemical potentials. Magnetization is found to be positive, which indicates the paramagnetic nature of the cold quark matter. We also discuss the resulting pressure anisotropy, where the transverse pressure is suppressed relative to the longitudinal pressure in the strong-field regime.

hep-ph↗
arXiv2025

Thermodynamics of strongly magnetized dense quark matter from hard dense loop perturbation theory

We discuss the hard dense loop perturbation theory approach for studying the thermodynamics of strongly magnetized dense quark matter. The free energy of quarks and gluons have been calculated for one-loop quark and gluon self-energies, respectively. The longitudinal and transverse components of pressure, magnetization, second-order quark number susceptibility, and speed of sound have been computed, and their behavior with chemical potential and magnetic field has been analyzed. Our numerical results show that the longitudinal pressure increases with chemical potential and magnetic field, while for the transverse component, it is diminished. We also analyze the longitudinal component of the speed of sound at high chemical potentials, which approaches the speed of light in the asymptotic limit. The obtained results may be helpful in studying magnetized quark matter in the core of neutron stars and magnetars.

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arXiv2024

Shear viscosity of rotating, hot, and dense spin-half fermionic systems from quantum field theory

In this study, we calculate the shear viscosity for rotating fermions with spin-half under conditions of high temperature and density. We employ the Kubo formalism, rooted in finite-temperature quantum field theory, to compute the field correlation functions essential for this evaluation. The one-loop diagram pertinent to shear viscosity is analyzed within the context of curved space, utilizing tetrad formalism as an effective approach in cylindrical coordinates. Our findings focus on extremely high angular velocities, ranging from 0.1 to 1 GeV, which align with experimental expectations. Furthermore, we explore the inter-relationship between the chemical potential and angular velocity within the scope of this study.

hep-ph↗
arXiv2023

Bulk viscosity of rotating, hot and dense spin 1/2 fermionic systems from correlation functions

In this work we have presented the one-loop calculation of the bulk viscosity of a system of rotating, hot and dense spin 1/2 fermions within the framework of Kubo formalism calculated from correlation functions of fields which in turn is used to calculate the spectral function of energy-momentum tensors. The calculation has been done in curved space by the help of tetrad formalism, where the the gamma matrices in this set-up assume their generic structure by becoming space dependent. The techniques of thermal field theory have been employed which take into account the three energy scales viz. temperature, chemical potential and angular velocity into account in the Matsubara frequency summation. The study has been performed in the ambience of very large angular velocities, ranging from 0.1 to 1.0 GeV. The fermion propagator used in this work is appropiate for the regime of large angular velocities. We explore the behaviour of bulk viscosity with angular velocity, temperature and chemical potential through our plots.

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arXiv2023

Spatial diffusion of heavy quarks in background magnetic field

The ratio of shear viscosity to entropy density shows a valley-shaped pattern well-known in the community of heavy-ion physics. Diffusion coefficients of heavy quark and meson shows the similar structure, and both sketches have become quite popular in the community. Present work has attempted a finite magnetic field extension of the diffusion coefficients of heavy quark and meson. Using Einstein's diffusion relation, we calculated heavy quark and heavy meson diffusion by the ratio of conductivity to susceptibility in the kinetic theory framework of relaxation time approximation. The relaxation time of heavy quark and meson are tuned from the knowledge of earlier works on spatial diffusion estimations, and then we have extended the framework for a finite magnetic field, where our outcomes have revealed two aspects - anisotropic and quantum aspects of diffusion with future possibilities of phenomenological signature.

hep-ph↗
arXiv2023

Quantum expression for the electrical conductivity of massless quark matter and of the hadron resonance gas in the presence of a magnetic field

We have studied the classical and quantum expressions of electrical conductivity and their numerical estimation in the presence of a magnetic field for hadron resonance gas (HRG) and massless quark matter. Classical results of transport coefficients of HRG matter in the presence of a magnetic field were studied previously by Dash et al. [Phys. Rev. D 102, 016016 (2020)] using the standard relaxation time approximation in the Boltzmann equation. In the same reference, the transition from isotropic transport coefficients to anisotropic coefficients in the presence of a magnetic field was also estimated for massless and HRG matter. This led to an upper limit or Stefan-Boltzmann (SB) type limit to the nonperturbative domain transition of transport coefficients. In a similar context, the present work has concentrated on the classical to quantum transition of HRG transport from the domain of high temperature and low magnetic field to that of low temperature and high magnetic field. We have also compared the quantum modification of HRG results with that of massless quark matter, where we observed an opposite trend. A similar kind of quantum effect is also noticed between mesons and baryons due to their different particle distribution functions. Despite the fact that HRG contains both mesons and baryons, Landau quantization of its net magnetothermodynamic phase space reveals meson- or boson-dominated quantum modification. That is why the quantum modification of HRG results reveals the opposite trend from that of massless quark matter, which faces fermionic quantum modification.

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arXiv2022

Dynamics of Hot QCD Matter -- Current Status and Developments

The discovery and characterization of hot and dense QCD matter, known as Quark Gluon Plasma (QGP), remains the most international collaborative effort and synergy between theorists and experimentalists in modern nuclear physics to date. The experimentalists around the world not only collect an unprecedented amount of data in heavy-ion collisions, at Relativistic Heavy Ion Collider (RHIC), at Brookhaven National Laboratory (BNL) in New York, USA, and the Large Hadron Collider (LHC), at CERN in Geneva, Switzerland but also analyze these data to unravel the mystery of this new phase of matter that filled a few microseconds old universe, just after the Big Bang. In the meantime, advancements in theoretical works and computing capability extend our wisdom about the hot-dense QCD matter and its dynamics through mathematical equations. The exchange of ideas between experimentalists and theoreticians is crucial for the progress of our knowledge. The motivation of this first conference named "HOT QCD Matter 2022" is to bring the community together to have a discourse on this topic. In this article, there are 36 sections discussing various topics in the field of relativistic heavy-ion collisions and related phenomena that cover a snapshot of the current experimental observations and theoretical progress. This article begins with the theoretical overview of relativistic spin-hydrodynamics in the presence of the external magnetic field, followed by the Lattice QCD results on heavy quarks in QGP, and finally, it ends with an overview of experiment results.

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arXiv2022

Quantum field theoretical structure of electrical conductivity of cold and dense fermionic matter in the presence of a magnetic field

We have gone through a detailed calculation of the two-point correlation function of vector currents at finite density and magnetic field by employing the real time formalism of finite temperature field theory and Schwinger's proper time formalism. With respect to the direction of external magnetic field, the parallel and perpendicular components of electric conductivity for the degenerate relativistic fermionic matter are obtained from the zero momentum limit of the current-current correlator, owing to Kubo formula. Our quantum field theoretical expressions and numerical estimations are compared with the same, obtained from the relaxation time approximation methods of kinetic theory and its Landau quantized extension, which may be called as classical and quantum results respectively. All the results are merged in the classical domain i.e. high density and low magnetic field region but in the remaining (quantum) domain, quantum results carry a quantized information like Shubnikov-de Haas oscillation along density and magnetic field axes. We have obtained completely new quantum field theoretical expression for perpendicular conductivity of degenerate relativistic fermionic matter. Interestingly, our quantum field theoretical calculation provide a new mathematical form of cyclotron frequency with respect to its classical definition, which might require more future research to interpret the phenomena.

hep-ph↗
arXiv2021

Kubo estimation of the electrical conductivity for a hot relativistic fluid in the presence of a magnetic field

We have explored the multi-component structure of electrical conductivity of relativistic Fermionic and Bosonic fluid in presence of magnetic field by using Kubo approach. This is done by explicitly evaluating the thermo-magnetic vector current spectral functions using the real time formalism of finite temperature field theory and the Schwinger proper time formalism. In absence of magnetic field, the one-loop diagramatic representation of Kubo expression of any transport coefficients is exactly same with relaxation time approximation (RTA) based expression, but this equality does not hold for finite magnetic field picture due to lacking of proper implementation of quantum effect in latter approach. We have shown this discrepancy for particular transport coefficient - electrical conductivity, whose starting point in Kubo approach will be electromagnetic current-current correlator and its one-loop skeleton diagram carrying two scalar/Dirac propagators for scalar/Dirac fluid. Through a numerical comparison between RTA and Kubo expressions of conductivity components (parallel and perpendicular), we have attempted to interpret detail quantum field theoretical effect, contained by Kubo expression but not by RTA expression. In classical RTA expression we get magnetic field independent parallel conductivity due to zero Lorentz force but in field theoretical Kubo expression, it decreases and increases with the magnetic field for scalar and Dirac medium respectively due to Landau quantization effect. This parallel component of conductivity can be interpreted as zero momentum limit of quantum fluctuation with same Landau level internal lines. While for perpendicular component of conductivity, fluctuation with Landau level differences $\pm 1$ are noticed, which might be a new realization of transportation in field theoretical sector.

hep-ph↗
arXiv2021

From Non-interacting to Interacting Picture of Quark Gluon Plasma in presence of magnetic field and its fluid property

We have attempted to build a parametric based simplified and analytical model to map the interaction of quarks and gluons in presence of magnetic field, which has been constrained by quark condensate and thermodynamical quantities like pressure, energy density etc., obtained from the calculation of lattice quantum chromodynamics. To fulfill that mapping, we have assumed a parametric temperature and magnetic field dependent degeneracy factor, average energy, momentum and velocity of quarks and gluons. Implementing this QCD interaction in calculation of transport coefficient at finite magnetic field, we have noticed that magnetic field and interaction both are two dominating sources, for which the values of transport coefficients can be reduced. Though the methodology is not so robust, but with the help of its simple parametric expressions, one can get a quick rough estimation of any phenomenological quantity, influenced by temperature and magnetic field dependent QCD interaction.

hep-ph↗
arXiv2021

Dynamics of QCD Matter -- current status

In this article, there are 18 sections discussing various current topics in the field of relativistic heavy-ion collisions and related phenomena, which will serve as a snapshot of the current state of the art. Section 1 reviews experimental results of some recent light-flavored particle production data from ALICE collaboration. Other sections are mostly theoretical in nature. Very strong but transient magnetic field created in relativistic heavy-ion collisions could have important observational consequences. This has generated a lot of theoretical activity in the last decade. Sections 2, 7, 9, 10 and 11 deal with the effects of the magnetic field on the properties of the QCD matter. There are several unanswered questions about the QCD phase diagram. Sections 3, 11 and 18 discuss various aspects of the QCD phase diagram and phase transitions. Recent years have witnessed interesting developments in foundational aspects of hydrodynamics and their application to heavy-ion collisions. Sections 12, 15, 16 and 17 of this article probe some aspects of this exciting field. Transport coefficients together with their temperature- and density-dependence, are essential inputs in hydrodynamical calculations. Sections 5, 8 and 14 deal with calculation/estimation of various transport coefficients (shear and bulk viscosity, thermal conductivity, relaxation times, etc.) of quark matter and hadronic matter. Sections 4, 6 and 13 deals with interesting new developments in the field. Section 4 discusses color dipole gluon distribution function at small transverse momentum in the form of a series of Bells polynomials. Section 6 discusses the properties of Higgs boson in the quark gluon plasma using Higgs-quark interaction. Section 13 discusses modification of coalescence model to incorporate viscous corrections and application of this model.

hep-ph↗
arXiv2020

Shear viscosity and electrical conductivity of relativistic fluid in presence of magnetic field: a massless case

We have explored the shear viscosity and electrical conductivity calculations for bosonic and fermionic medium, which goes from without to with magnetic field picture and then their simplified massless expressions. In presence of magnetic field, 5 independent velocity gradient tensors can be designed, so their corresponding proportional coefficients, connected with the viscous stress tensor provide us 5 shear viscosity coefficients. In existing litterateurs, two sets of tensors are available. Starting from them, present work has obtained two sets of expressions for 5 shear viscosity coefficients, which can be ultimately classified into three basic components: parallel, perpendicular and Hall components as one get same for electrical conductivity at finite magnetic field. Our calculations are based on kinetic theory approach in relaxation time approximation. Repeating same mathematical steps for finite magnetic field picture, which traditionally practiced for without field case, we have obtained 2 sets of 5 shear viscosity components, whose final expressions are in well agreements with earlier references, although a difference in methodology or steps can be clearly noticed. Realizing the massless results of viscosity and conductivity for Maxwell-Boltzmann, Fermi-Dirac and Bose-Einstein distribution function, we have applied them for massless quark gluon plasma and hadronic matter phases, which can provide us a rough order of strength, within which actual results will vary during quark-hadron phase transition. Present work also indicates that magnetic field might have some role for building perfect fluid nature in RHIC or LHC matter. The lower bound expectation of shear viscosity to entropy density ratio is also discussed.

hep-ph↗
arXiv2020

On lower bound of relaxation time for massless fluid in presence of magnetic field

Due to lowest possible quantum fluctuation, shear viscosity to entropy density ratio never reach to zero, rather has some lower bound (0.08 approx). Here, we have attempted to link our calculation, based on relaxation time approximation for massless relativistic fluid, with that value and interestingly found a lower and also an upper limit of relaxation time.

hep-ph↗
arXiv2020

Collisional time and shear relaxation time for interacting QGP

We have studied the collisional time and relaxation time of a QGP(Quark-Gluon Plasma) by parameterizing them by temperature. From this parameterization we have obtained the decay rate parameterized by temperature which further helps us to calculate and compare the shear viscosity to entropy density ratio of a QGP with the KSS(Kovtun-Son-Starinets) result.

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arXiv2020

Fluid property of QGP in presence of magnetic field

Fluidity of quark-gluon plasma (QGP) is studied where interaction between quark and gluon is mapped through fugacity in particle distribution function using lattice quantum chromodynamics (LQCD) results.

hep-ph↗
arXiv2019

From Non-interacting to Interacting Picture of Thermodynamics and Transport Coefficients for Quark Gluon Plasma

We have attempted to build first some simplified model to map the interaction of quarks and gluons, which can be contained by their thermodynamical quantity like entropy density, obtained from calculation of lattice quantum chromo dynamics (LQCD). With respect to entropy density of the standard non-interacting massless quark gluon plasma (QGP), its interacting values from LQCD simulation are reduced as we go from higher to lower temperature through the cross-over of quark-hadron phase transition. By parameterizing increasing degeneracy factor or increasing interaction-fugacity or decreasing thermal width of quarks and gluons with temperature, we have matched LQCD data.Using that interaction picture, shear viscosity and electrical conductivity are calculated. For getting nearly perfect fluid nature of QGP, interaction might have some role when we consider temperature dependent thermal width.

hep-ph↗