arXiv subjects

Binoy Krishna Patra

Publications and source records attributed to Binoy Krishna Patra.

At least 19 recordsLinked to original sources

arXiv2025

Generalized relativistic second order magnetohydrodynamics: A correlation function approach using Zubarev's nonequilibrium statistical operator

We use total energy-momentum conservation and the Bianchi identity (magnetic-flux conservation) to construct second-order relativistic magnetohydrodynamics in a Zubarev's non-equilibrium statistical operator (NESO) framework. We obtain all dissipative tensors in the medium by focusing on a relativistic magnetized plasma that preserves parity and is symmetric to charge-conjugation. We also provide Kubo formulas for all transport coefficients that arise at second order. Moreover, we extend the NESO formalism to systematically take into account for nonlocal contributions.

physics.flu-dyn↗

arXiv2025

Second-order spin hydrodynamics from Zubarev's nonequilibrium statistical operator formalism

Using the Zubarev's nonequilibrium statistical operator formalism, we derive the second-order expression for the dissipative tensors in relativistic spin hydrodynamics, {\em viz.} rotational stress tensor ($τ_{μν}$), boost heat vector ($q_μ$), shear stress tensor ($π_{μν}$), and bulk viscous pressure ($Π$). The first two ($τ_{μν}$ and $q_μ$) emerge due to the inclusion of the antisymmetric part in the energy-momentum tensor, which, in turn, governs the conservation of spin angular momentum ($Σ^{αμν}$). As a result, new thermodynamic forces, generated due to the antisymmetric part of $T_{μν}$, contain the spin chemical potential. In this work, we have also taken the spin density ($S^{μν}$) as an independent thermodynamic variable, in addition to the energy density and particle density, thereby resulting in two novel transport coefficients given by the correlation between spin density tensor and rotational stress tensor and vice versa. Additionally, the newly found terms in $π_{μν}$ and $Π$ are the artifacts of the new thermodynamic forces that arise due to the antisymmetric part of $T^{μν}$. Finally, we have derived the evolution equations for the aforesaid tensors: $τ_{μν}$, $q_μ$, $π_{μν}$, and $Π$.

hep-th↗

arXiv2024

Dynamics of Hot QCD Matter 2024 -- Hard Probes

The hot and dense QCD matter, known as the Quark-Gluon Plasma (QGP), is explored through heavy-ion collision experiments at the LHC and RHIC. Jets and heavy flavors, produced from the initial hard scattering, are used as hard probes to study the properties of the QGP. Recent experimental observations on jet quenching and heavy-flavor suppression have strengthened our understanding, allowing for fine-tuning of theoretical models in hard probes. The second conference, HOT QCD Matter 2024, was organized to bring the community together for discussions on key topics in the field. This article comprises 15 sections, each addressing various aspects of hard probes in relativistic heavy-ion collisions, offering a snapshot of current experimental observations and theoretical advancements. The article begins with a discussion on memory effects in the quantum evolution of quarkonia in the quark-gluon plasma, followed by an experimental review, new insights on jet quenching at RHIC and LHC, and concludes with a machine learning approach to heavy flavor production at the Large Hadron Collider.

nucl-ex↗

arXiv2024

Dynamics of Hot QCD Matter 2024 -- Bulk Properties

The second Hot QCD Matter 2024 conference at IIT Mandi focused on various ongoing topics in high-energy heavy-ion collisions, encompassing theoretical and experimental perspectives. This proceedings volume includes 19 contributions that collectively explore diverse aspects of the bulk properties of hot QCD matter. The topics encompass the dynamics of electromagnetic fields, transport properties, hadronic matter, spin hydrodynamics, and the role of conserved charges in high-energy environments. These studies significantly enhance our understanding of the complex dynamics of hot QCD matter, the quark-gluon plasma (QGP) formed in high-energy nuclear collisions. Advances in theoretical frameworks, including hydrodynamics, spin dynamics, and fluctuation studies, aim to improve theoretical calculations and refine our knowledge of the thermodynamic properties of strongly interacting matter. Experimental efforts, such as those conducted by the ALICE and STAR collaborations, play a vital role in validating these theoretical predictions and deepening our insight into the QCD phase diagram, collectivity in small systems, and the early-stage behavior of strongly interacting matter. Combining theoretical models with experimental observations offers a comprehensive understanding of the extreme conditions encountered in relativistic heavy-ion and proton-proton collisions.

nucl-th↗

arXiv2024

Heavy quark dynamics via Gribov-Zwanziger approach

In this work, we investigate the momentum-dependent drag and diffusion coefficient of heavy quarks (HQs) moving in the quark-gluon plasma (QGP) background. The leading order scattering amplitudes required for this purpose have been obtained using the Gribov-Zwanziger propagator for the mediator gluons to incorporate the non-perturbative effects relevant to the phenomenologically accessible temperature regime. The drag and diffusion coefficients so obtained have been implemented to estimate the temperature and momentum dependence of the energy loss of the HQ as well as the temperature dependence of the specific shear viscosity ($η/s$) of the background medium. Our results suggest a higher energy loss of the propagating HQ compared to the perturbative estimates, whereas the $η/s$ is observed to comply with the AdS/CFT estimation over a significantly wider temperature range compared to the perturbative expectation.

hep-ph↗

arXiv2024

Causal third-order viscous hydrodynamics within relaxation-time approximation

In the present work, we derive a linearly stable and causal theory of relativistic third-order viscous hydrodynamics from the Boltzmann equation with relaxation-time approximation. We employ viscous correction to the distribution function obtained using a Chapman-Enskog like iterative solution of the Boltzmann equation. Our derivation highlights the necessity of incorporating a new dynamical degree of freedom, specifically an irreducible tensors of rank three, within this framework. This differs from the recent formulation of causal third-order theory from the method of moments which requires two dynamical degrees of freedom: an irreducible third-rank and a fourth-rank tensor. We verify the linear stability and causality of the proposed formulation by examining perturbations around a global equilibrium state.

hep-ph↗

arXiv2024

Momentum transport of chiral modes in a thermal QCD medium

We have investigated the effect of a weak magnetic field on momentum transport in a thermal QCD medium at finite quark chemical potential using a semiclassical kinetic theory. In the presence of a magnetic field, the momentum transport coefficients acquire a tensor structure, reflected by the five shear $\left(η_0, η_1, η_2, η_3\right.$ and $\left.η_4\right)$ and two bulk viscous components $\left(ζ_0\right.$ and $\left. ζ_1\right)$. The weak magnetic field removes the degeneracy in the effective mass of flavours, leading to different masses for the left-handed (L) and right-handed (R) chiral modes of quarks. The coefficients, $η_0, η_1$ and $η_3$ decrease with magnetic field in L mode and increase in $\mathrm{R}$ mode, whereas, $η_2$ and $η_4$ increase in both L and $\mathrm{R}$ mode. The bulk viscous coefficients, $ζ_0$ and $ζ_1$ increase with magnetic field for both L and R mode. The shear and bulk viscous coefficients positively amplify with baryon asymmetry.

nucl-th↗

arXiv2023

QCD mesonic screening masses using Gribov quantization

The screening masses of mesons provide a gauge invariant and definite order parameter of chiral symmetry restoration. Different mesonic correlation lengths for flavor non-singlets, at least up to NLO, are well-defined gauge invariant physical quantities calculated earlier using the perturbative resummation techniques. The NLO perturbative results match the available non-perturbative lattice QCD results at the high-temperature regime. We have studied the spatial correlation lengths of various mesonic observables using the non-perturbative Gribov resummation, both for quenched QCD and (2 + 1) flavor QCD. The study follows the analogies with the NRQCD effective theory, a well-known theory for studying heavy quarkonia at zero temperature.

hep-ph↗

arXiv2023

Seebeck and Nernst coefficients of a magnetized hot QCD medium with number conserving kernel

We have studied the thermoelectric response of a hot and magnetized QCD medium created in the noncentral events at heavy-ion collider experiments. The collisional aspects of the medium have been embedded in the relativistic Boltzmann transport equation (RBTE) using Bhatnagar-Gross-Krook (BGK) collision integral, which insures the particle number conservation, unlike the commonly used relaxation time approximation (RTA). We have incorporated the thermal medium effects in the guise of a quasiparticle model, where the interaction among the partons is embodied in the medium dependent mass of the quark, which has been evaluated using the framework of the perturbative thermal QCD with a magnetic field in the background. In the absence of $B$, the Seebeck coefficient for individual quark flavors gets slightly reduced in the BGK term in comparison to naive RTA, while it gets enhanced for the composite partonic medium. In the presence of strong magnetic field ($B$), the BGK term enhances the Seebeck coefficient for the individual flavors as well as that for medium. The medium Seebeck coefficient rises with the strength of quark chemical potential ($μ$) in the absence as well as that in the strong $B$. We observe chirality dependence in the Seebeck and Nernst coefficients in the weak magnetic field as the degeneracy in the masses of left- and right-handed chiral modes gets lifted in the weak $B$. Seebeck coefficient is larger for left-handed modes contrary to the Nernst coefficient which is higher for the right-handed modes. Seebeck coefficient is almost similar in the weak field for both the collision term, while Nernst coefficient gets reduced (enhanced) for $L$ ($R$) modes considerably in the BGK collision term.

hep-ph↗

arXiv2023

NLO quark self-energy and dispersion relation using the hard thermal loop resummation

Using the hard-thermal-loop (HTL) resummation in real-time formalism, we study the next-to-leading order (NLO) quark self-energy and corresponding NLO dispersion laws. In NLO, we have replaced all the propagators and vertices with the HTL-effective ones in the usual quark self-energy diagram. Additionally, a four-point vertex diagram also contributes to the quark NLO self-energy. We calculate the usual quark self-energy diagram and the four-point vertex diagram separately. Using those, we express the NLO quark self-energy in terms of the three- and four-point HTL-effective vertex functions. Using the Feynman parametrization, we express the integrals containing the three- and four-point HTL effective vertex functions in terms of the solid angles. After completing the solid angle integrals, we numerically calculate the momentum integrals in the NLO quark self-energy and plot them as a function of the ratio of momentum and energy. Using the NLO quark self-energy, we plot the NLO correction to dispersion laws.

hep-ph↗

arXiv2023

Heavy quarkonia in a baryon asymmetric strongly magnetized hot quark matter

Recently there is a resurrection in the study of heavy quark bound states in a hot and baryonless matter with an ambient magnetic field but the matter produced at heavy-ion collider experiments is not perfectly baryonless, so we wish to explore the effect of small baryon asymmetry on the properties of heavy quarkonia immersed in a strongly magnetized hot quark matter. Therefore, we have first revisited the structure of gluon self-energy tensor in the above environment to compute the resummed propagator for gluons. This resummed propagator embodies the properties of medium, which gets translated into the (complex) potential between $Q$ and $\bar Q$ placed in the medium. We observe that the baryon asymmetry makes the real-part of potential slightly more attractive and weakens the imaginary-part. This opposing effects thus lead to the enhancement of binding energies and the reduction of thermal widths of $Q \bar Q$ ground states, respectively. Finally, the properties of quarkonia thus deciphered facilitates to compute the dissociation points of $J/ψ$ and $Υ$, which are found to have slightly larger values in the presence of baryon asymmetry. For example, $J/ψ$ is dissociated at $1.64~T_c$, $1.69~T_c$, and $1.75~T_c$, whereas $Υ$ is dissociated at $1.95~T_c$, $1.97~T_c$ and $2.00 ~T_c$, for $μ=0, 60$ and $ 100 $ MeV, respectively. This observation prevents early dissociation of quarkonia in the matter produced at ultrarelativistic heavy ion collisions with a small net baryon number, compared to the ideal baryonless matter.

hep-ph↗

arXiv2022

Transport coefficients in thermal QCD: A probe to the collision integral

We have studied the transport coefficients as a tool to probe the collision integral appeared in the Boltzmann equation. For this purpose, we have estimated the transport coefficients (momentum: \{$η$,$ζ$\}, heat: \{$κ$\}, and charge: \{$σ_{\rm el}$\}) in the kinetic theory with Bhatnagar-Gross-Krook (BGK) and the collision integral in RTA and ask whether we can distinguish between the two collision integrals. For example, $η$ gets enhanced while $ζ$ gets reduced w.r.t. to RTA. As a corollary, we then investigate the interplay among the aforesaid transport coefficients, {\em viz.} fluidity and transition point of QCD medium by evaluating the ratios, $η/s$ and $ζ/s$, respectively, nature of flow (Reynolds number, RI), sound attenuation (Prandtl number, Pr), and competition between the momentum and charge diffusion ($γ$) etc. as further plausible tools to decipher the same. With BGK collision integral, the ratios, $η/s$ (increase) and $ζ/s$ (decrease) shows opposite behavior whereas Pr, RI, $γ$ and the ratio $ζ/η$ get reduced w.r.t RTA. We then examine how a strong $B$ modulate the impact of collision integral, which, in a way, explore the dimensionality dependence of the momentum transport because the quark dynamics gets restricted to 1-D only and only the lowest Landau levels are populated. As a result, $η$ ($ζ$) gets reduced (amplified), which will have ramifications on the ratios, {\em viz.} $η/s$ ($ζ/s$) becomes smaller (larger), enhancement of Pr, $γ$ and $ζ/η$ etc. In this study, the thermo-magnetic medium effects have been incorporated by adopting a quasi-particle model, where the medium generated masses of the partons have been obtained from the pole of their resummed propagators calculated using perturbative thermal QCD in strong $B$.

hep-ph↗

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.

nucl-th↗

arXiv2022

Chirality dependence in charge and heat transport in thermal QCD

In the presence of weak magnetic field ($B$), novel phenomena, similar to Hall effect in condensed matter physics, emerge both in charge and heat transport in a thermal QCD medium. Here, we have employed the kinetic theory approach within a quasiparticle framework, wherein the effective masses for left (L) and right-handed (R) chiral modes of quarks are seen different, lifting the prevalent degeneracy. Another implication of weak $B$ is that the coefficients assume a tensorial structure: The diagonal elements represent the usual conductivities: $σ_{\text{Ohmic}}$ and $κ_0$ as the coefficients of charge and heat transport, respectively and the off-diagonal elements denote their Hall counterparts: $σ_{\text{Hall}}$ and $κ_1$, respectively. Finally, we have derived some coefficients, namely, the Knudsen number and Lorenz number in Wiedemann-Franz law. Lorenz number and Hall-Lorenz number for L-mode increases and for R-mode decreases with a magnetic field. it does not remain constant with $T$ hence violating the Wiedemann-Franz law.

nucl-th↗

arXiv2022

Chirality dependence of thermoelectric response in a thermal QCD medium

The lifting of the degeneracy between L- and R-modes of massless flavors in a weakly magnetized thermal QCD medium leads to a novel phenomenon of chirality dependence of the thermoelectric tensor, whose diagonal and non-diagonal elements are the Seebeck and Hall-type Nernst coefficient, respectively. Both coefficients in L-mode have been found to be greater than their counterparts in R-mode, however the disparity is more pronounced in the Nernst coefficient. Another noteworthy observation is the impact of the dimensionality of temperature (T) profile on the Seebeck coefficient, wherein we find that the coefficient magnitude is significantly enhanced (one order of magnitude) in the 2-D setup, compared to a 1-D T profile. Further, the chiral dependent quasifermion masses constrain the range of magnetic field (B) and T in a manner so as to enforce the weak magnetic field (eB << T^2 ) condition.

hep-ph↗

arXiv2021

Thermoelectric response of a weakly magnetized thermal QCD medium

We estimate the thermoelectric response, namely, the Seebeck and Nernst coefficients of a hot and deconfined plasma of quarks and gluons, created post ultrarelativistic heavy ion collisions in the presence of a weak, homogeneous background magnetic field. We employ the kinetic theory framework, wherein we use the relativistic Boltzmann transport equation in the relaxation time approximation. In-medium interactions are taken into account via the quasiparticle masses of the partons extracted from one loop perturbative thermal QCD. We calculate the individual and total Seebeck coefficients in 2 different approaches (1-D and 2-D formulations). In the 1-D analysis, we find that a larger current quark mass has an amplifying effect on the individual Seebeck coefficient in the presence of a weak magnetic field. The temperature sensitivities of the individual Seebeck coefficients increase with increase in the current mass of the quark species in the case of a weak magnetic field whereas the same records a decreasing trend in the presence of a strong magnetic field. The variation of individual and total Seebeck coefficients with temperature, chemical potential and background magnetic field are found to follow similar trends in both the approaches, viz. decrease in magnitude with increasing temperature and increase in magnitude with increase in chemical potential and magnetic field. We also calculate the individual and total Nernst coefficients (in 2-D formulation) which are found to decrease with both temperature and chemical potential and increase with the magnetic field. Further, we find that the sign of the Nernst coefficient is independent of the electric charge of the charge carrier of the medium.

nucl-th↗

arXiv2021

Cumulative effects of collision integral, strong magnetic field, and quasiparticle description on charge and heat transport in thermal QCD medium

Our first aim is to explore the effect of the collision integral with the insurance of instantaneous conservation of particle number on charge and heat transport in a thermal QCD medium. The second aim is to see how the dimensional reduction due to strong magnetic field (B) modulates the transport through the entangled effects, {\em such as} collision-time and occupation probability etc. in collision integral. The final aim is to check how the quasiparticle description through dispersion relation of thermal QCD in strong B, alters the aforesaid conclusions. We observe that modified collision term expedites both transport, which is manifested by large magnitudes of electrical ($σ_{\rm el}$) and thermal ($κ$) conductivities, in comparison to relaxation-collision term. As a corollary, Lorenz number is dominated by the later and Knudsen number is by the former. However, strong B not only flips the dominance of collision term in heat transport, it also causes drastic enhancement of both $σ_{\rm el}$ and $κ$ and reduction in specific heat. As a result, the equilibration factor, Knudsen number becomes much larger than one, which defies physical interpretation. Finally, quasiparticle description in the absence of strong B impedes the transport of charge and heat, resulting in the meagre decrease of conductivities, however, strong B does noticeable observations: conductivities now gets reduced to physically plausible values, T-dependence of $σ_{\rm el}$ gets reversed, {\em i.e.} it now decreases with T, effect of collision integral gets smeared in $κ$ etc. Knudsen number thus becomes much smaller than one, implying that the system be remained in equilibrium. These findings attribute to the fact that the collective modes in the dispersion relation of thermal QCD in strong B sets in much larger scale, manifested by large in-medium masses.

hep-ph↗

arXiv2021

Viscous properties of hot and dense QCD matter in the presence of a magnetic field

We have studied the effect of strong magnetic field on the viscous properties of hot QCD matter at finite chemical potential by calculating the shear ($η$) and bulk ($ζ$) viscosities. The viscosities are calculated using kinetic theory in the relaxation time approximation. The interactions are incorporated through the quasiparticle masses of partons at strong magnetic field and finite chemical potential. From this study, one can understand the effects of strong magnetic field and chemical potential on the sound attenuation through the Prandtl number (Pl), on the nature of the flow by the Reynolds number (Rl), and on the relative behavior between shear viscosity and bulk viscosity through the ratio $ζ/η$. We have found that, $η$ and $ζ$ get increased in a strong magnetic field and the additional presence of chemical potential further enhances their magnitudes. With the increase of temperature, $η$ increases in a strong magnetic field as well as in the absence of magnetic field, whereas $ζ$ decreases with the temperature, contrary to its increase in the absence of magnetic field. We have observed that, the Prandtl number gets increased in the presence of strong magnetic field and chemical potential as compared to the isotropic one, but it always remains larger than 1, thus the momentum diffusion largely affects the sound attenuation in the medium. The Reynolds number gets lowered than 1 in a strong magnetic field and it becomes further decreased in an additional presence of chemical potential, so the kinematic viscosity dominates over the characteristic length scale of the system. Finally, $ζ/η$ becomes larger than 1, contrary to its value in the absence of magnetic field and chemical potential where it is less than 1, so the bulk viscosity prevails over the shear viscosity for the hot and dense QCD matter in the presence of a strong magnetic field.

hep-ph↗