Binoy Patra - Academia.edu (original) (raw)

Papers by Binoy Patra

arXiv (Cornell University), Feb 16, 2018

In this article we have investigated the effects of strong magnetic field on the properties of qu... more In this article we have investigated the effects of strong magnetic field on the properties of quarkonia immersed in a thermal medium of quarks and gluons and studied its quasi-free dissociation due to the Landau-damping. Thermalizing the Schwinger propagator in the lowest Landau levels for quarks and the Feynman propagator for gluons in real-time formalism, we have calculated the resummed retarded and symmetric propagators, which in turn give the real and imaginary components of dielectric permittivity, respectively. Thus the effect of a strongly magnetized hot QCD medium have been encrypted into the real and imaginary parts of heavy quark interaction in medium, respectively. The magnetic field affects the large-distance interaction more than the short-distance interaction, as a result, the real part of potential becomes more attractive and the magnitude of imaginary part too becomes larger, compared to the thermal medium in absence of strong magnetic field. As a consequence the average size of J/ψ's and ψ ′ 's are increased but χ c 's get shrunk. Similarly the magnetic field affects the binding of J/ψ's and χ c 's discriminately, i.e. it decreases the binding of J/ψ and increases for χ c. However, the further increase in magnetic field results in the decrease of binding energies. On contrary the magnetic field increases the width of the resonances, unless the temperature is sufficiently high. We have finally studied how the presence of magnetic field affects the dissolution of quarkonia in a thermal medium due to the Landau damping, where the dissociation temperatures are found to increase compared to the thermal medium in absence of magnetic field. However, further increase of magnetic field decreases the dissociation temperatures. For example, J/ψ's and χ c 's are dissociated at higher

arXiv (Cornell University), Jan 11, 2019

We have investigated how the wakes in the induced charge density and in the potential due to the ... more We have investigated how the wakes in the induced charge density and in the potential due to the passage of highly energetic partons through a thermal QCD medium get affected by the presence of strong magnetic field (B). For that purpose, we wish to analyze first the dielectric responses of the medium both in presence and absence of strong magnetic field. Therefore, we have revisited the general form for the gluon self-energy tensor at finite temperature and finite magnetic field and then calculate the relevant structure functions at finite temperature and strong magnetic field limit (SMF: |q f B| ≫ T 2 as well as |q f B| ≫ m 2 f , q f (m f) is the electric charge (mass) of f-th flavour). We found that for slow moving partons, the real part of dielectric function is not affected by the magnetic field whereas for fast moving partons, for small |k|, it becomes very large and approaches towards its counterpart at B = 0, for large |k|. On the other hand the imaginary part is decreased for both slow and fast moving partons, due to the fact that the imaginary contribution due to quark-loop vanishes. With these ingredients, we found that the oscillation in the (scaled) induced charge density, due to the very fast partons becomes less pronounced in the presence of strong magnetic field whereas for smaller parton velocity, no significant change is observed. For the (scaled) wake potential along the motion of fast moving partons (which is of Lennard-Jones (LJ) type), the depth of negative minimum in the backward region gets reduced drastically, resulting in the reduction of the amplitude of oscillation. On the other hand in the forward region, it remains as the screened Coulomb one, except the screening now becomes much stronger for higher parton velocity. Similarly for the wake potential transverse to the motion of partons in both forward and backward regions, the depth of LJ potential for fast moving partons gets decreased severely, but still retains the forward-backward symmetry. However, for lower parton velocity, the magnetic field does not affect it significantly.

Physical review, Apr 25, 2023

We study the thermoelectric response of a hot and magnetized QCD medium created in the noncentral... more We study 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 the 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 quarks and gluons is assimilated in the medium dependent masses of the quarks, which have been evaluated using imaginary-time formalism of thermal QCD with a background magnetic field. 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 strong magnetic field (B), the BGK term enhances the Seebeck coefficient for the individual flavors, as well as that for the 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 transport coefficients in the weak B as the masses of chiral modes become nondegenerate. In the case of the L modes, the BGK collision term causes a slight reduction in the Seebeck coefficient, while for R modes both the collision integrals produce the same results. The Nernst coefficient gets reduced (enhanced) for L (R) chiral modes in the BGK term.

arXiv (Cornell University), Nov 19, 2022

We study the thermoelectric response of a hot and magnetized QCD medium created in the noncentral... more We study 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 quarks and gluons is assimilated in the medium dependent masses of the quarks, which have been evaluated using imaginary-time formalism of thermal QCD with a background magnetic field. 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 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 transport coefficients in the weak B as the masses of chiral modes become nondegenerate. In the case of the L modes, the BGK collision term causes slight reduction in the Seebeck coefficient, while for R modes both the collision integral produces same results. Nernst coefficient gets reduced (enhanced) for L (R) chiral modes in the BGK term.

arXiv (Cornell University), Jun 6, 2016

We have calculated the quenching parameter,q in a model-independent way using the gauge-gravity d... more We have calculated the quenching parameter,q in a model-independent way using the gauge-gravity duality. In earlier calculations, the geometry in the gravity side at finite temperature was usually taken as the pure AdS blackhole metric for which the dual gauge theory becomes conformally invariant unlike QCD. Therefore we use a metric which incorporates the fundamental quarks by embedding the coincident D7 branes in the Klebanov-Tseytlin background and a finite temperature is switched on by inserting a black hole into the background, known as OKS-BH metric. Further inclusion of an additional UV cap to the metric prepares the dual gauge theory to run similar to thermal QCD. Moreoverq is usually defined in the literature from the Glauber-model perturbative QCD evaluation of the Wilson loop, which has no reasons to hold if the coupling is large and is thus against the main idea of gauge-gravity duality. Thus we use an appropriate definition ofq: qL − = 1/L 2 , where L is the separation for which the Wilson loop is equal to some specific value. The above two refinements causeq to vary with the temperature as T 4 always and to depend linearly on the light-cone time L − with an additional (1/L −) correction term in the short-distance limit whereas in the long-distance limit,q depends only linearly on L − with no correction term. These observations agree with other holographic calculations directly or indirectly.

Physics Letters B, Oct 1, 1996

We propose an alternative form of a thermodynamically consistent equation of state (EOS) incorpor... more We propose an alternative form of a thermodynamically consistent equation of state (EOS) incorporating the Van der Waals type of excluded volume effect for a hot and dense hadronic gas consisting of many species of finite-size baryons is obtained. We compare its predictions in detail with those of the other thermodynamically consistent as well as inconsistent models.

arXiv (Cornell University), Nov 5, 2020

Our first aim is to explore the effect of the collision integral with the insurance of instantane... more Our first aim is to explore the effect of the collision integral with the insurance of instantaneous conservation of particle number on the charge and heat transport in a thermal QCD medium. The second aim is to see how the dimensional reduction due to strong magnetic field modulates the transport through the entangled effects such as the collision-time and occupation probability etc. in the collision integral. Final aim is to check how the quasiparticle description of partons, through the dispersion relation of thermal QCD in strong magnetic field, alters the aforesaid conclusions. We observe that the modified collision term expedites both transport, which is manifested by the larger magnitudes of electrical (σ el) and thermal (κ) conductivities, in comparison to the relaxation collision term. As a corollary, the Lorenz number is dominated by the later and the Knudsen number is by the former. However, the strong magnetic field not only flips the dominance of collision term in the heat transport, it also causes drastic enhancement of both σ el and κ and reduction in the specific heat. As a result, the equilibration factor, the Knudsen number becomes much larger than one, which defies physical interpretation. Finally, the quasiparticle description of partons in the absence of strong magnetic field impedes the transport of charge and heat, resulting in tiny decrease of the conductivities. However, the strong magnetic field does noticeable observations: the conductivities now gets reduced to the physically plausible values, the temperature dependence of σ el gets reversed, i.e. it now decreases with temperature, effect of collision integral gets smeared in κ etc. The 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 oscillation in the dispersion relation of thermal QCD in strong magnetic field sets in much larger scale, manifested by the large in-medium flavour masses.

DAE Symp.Nucl.Phys., 2015

arXiv (Cornell University), Sep 11, 1998

Lattice QCD results reveal that the critical parameters and the order of the quark-hadron phase t... more Lattice QCD results reveal that the critical parameters and the order of the quark-hadron phase transition are quite sensitive to the number of dynamical flavours and their masses included in the theory. Motivated by this result we develop a phenomenological equation of state for the quark-gluon plasma consisting of n f flavours retaining the entropy per baryon ratio continuous across the quark-hadron phase boundary. We thus obtain a generalised expression for the temperature and baryon chemical potential dependent bag constant. The results are shown for the realistic case, i.e., involving u, d and s quarks only. We then obtain a phase boundary for an isentropic quark-hadron phase transition using Gibbs' criteria. Similarly another phase boundary is obtained for the transition to an ideal QGP from the solution of the condition B(µ, T) = 0. The variation of critical temperature T c with the number of flavours included in the theory. Also the variation of (ε − 4P)/T 4 with temperature are studied and compared with lattice results. Finally the strange particle ratios Λ Λ , Ξ Ξ and K + K − are obtained at both phase boundaries. We propose that their variations with the temperature and baryon chemical potential can be used in identifying the quark-gluon plasma in the recent as well as in future heavy-ion experiments.

arXiv (Cornell University), Jul 1, 2023

We calculate the momentum diffusion coefficients and energy loss of a heavy quark (HQ) traversing... more We calculate the momentum diffusion coefficients and energy loss of a heavy quark (HQ) traversing through the quark-gluon plasma in the presence of a weak magnetic field, upto leading order in the strong coupling αs. t channel Coulomb scatterings of the HQ with the thermal quarks and gluons are considered, whereas Compton scatterings and gluon radiation are neglected. The scale hierarchy considered in this work is MQ ≫ T ≫ eB/T. The calculations are carried out ina perturbative framework where the interaction rate Γ is calculated from the imaginary part of the HQ self energy. We find that the longitudinal and transverse momentum diffusion coefficients of the HQ decrease with temperature, whereas the energy loss increases with temperature. Variation with both the temperature and magnetic field is amplified for the Charm quark in comparison to bottom quark, due to the lighter mass of the former. We also find that the extent of anisotropy in the momentum diffusion coefficient depends strongly on the current mass of the HQ, with a lighter mass leading to a greater anisotropy.

arXiv (Cornell University), Nov 22, 2022

Physical review, Jun 15, 2022

As the strength of the magnetic field (B) becomes weak, novel phenomena, similar to the Hall effe... more As the strength of the magnetic field (B) becomes weak, novel phenomena, similar to the Hall effect in condensed matter physics, emerges both in charge and heat transport in a thermal QCD medium with a finite quark chemical potential (µ). So we have calculated the transport coefficients in a kinetic theory within a quasiparticle framework, wherein we compute the effective mass of quarks for the aforesaid medium in a weak magnetic field (B) limit (|eB| << T 2 ; T is temperature) by the perturbative thermal QCD up to one loop, which depends on T and B differently to left-(L) and right-handed (R) chiral modes of quarks, lifting the prevalent degeneracy in L and R modes in strong magnetic field limit (|eB| >> T 2). Another implication of weak B is that the transport coefficients assume a tensorial structure: The diagonal elements represent the usual (electrical and thermal) conductivities: σ Ohmic and κ0 as the coefficients of charge and heat transport, respectively and the off-diagonal elements denote their Hall counterparts: σ Hall and κ1, respectively. It is found in charge transport that the magnetic field acts on Land R-modes of the Ohmic-part of electrical conductivity in opposite manner, viz. σ Ohmic for L-mode decreases and for R-mode, increases with B whereas the Hall-part σ Hall for both Land R-modes always increases with B. In heat transport too, the effect of the magnetic field on the usual thermal conductivity (κ0) and Hall-type coefficient (κ1) in both modes is identical to the abovementioned effect of B on charge transport coefficients. We have then derived some coefficients from the above transport coefficients, namely Knudsen number (Ω is the ratio of the mean free path to the length scale of the system) and Lorenz number in Wiedemann-Franz law. The effect of B on Ω either with κ0 or with κ1 for both modes are identical to the behaviour of κ0 and κ1 with B. The value of Ω is always less than unity for the entire temperature range, validating our calculations. Lorenz number (κ0/σ Ohmic T) and Hall-Lorenz number (κ1/σ Hall T) for L-mode increases and for R-mode decreases with magnetic field. It also does not remain constant with temperature hence violating the Wiedemann-Franz law.

European Physical Journal C, Aug 16, 2006

In a recent paper [Eur. Phys. J C 44, 567 (2005)] we developed a very general formulation to take... more In a recent paper [Eur. Phys. J C 44, 567 (2005)] we developed a very general formulation to take into account explicitly the effects of hydrodynamic flow profile on the gluonic breakup of J/ψ's produced in an equilibrating quark-gluon plasma. Here we apply that formulation to the case when the medium is undergoing cylindrically symmetric transverse expansion starting from RHIC or LHC initial conditions. Our algebraic and numerical estimates demonstrate that the transverse expansion causes enhancement of local gluon number density n g , affects the p T-dependence of the average dissociation rate Γ through a partial-wave interference mechanism, and makes the survival probability S(p T) to change with p T very slowly. Compared to the previous case of longitudinal expansion the new graph of S(p T) is pushed up at LHC, but develops a rich structure at RHIC, due to a competition between the transverse catch-up time and plasma lifetime.

Nuclear Physics A

Recently there is a resurrection in the study of heavy quark bound states in a hot and baryonless... more 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 andQ 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 QQ 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.

International Journal of Modern Physics E

The discovery of hot and dense quantum chromodynamics (QCD) matter, known as Quark–Gluon Plasma (... more The discovery of hot and dense quantum chromodynamics (QCD) matter, known as Quark–Gluon Plasma (QGP), is an essential milestone in understanding the finite temperature QCD medium. Experimentalists around the world 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 at the Large Hadron Collider (LHC), at CERN in Geneva, Switzerland. The experimentalists 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. Recent advancements in theory, experimental techniques, and high computing facilities help us to better interpret experimental observations in heavy ion collisions. The exchange of ideas between experimentalists and theorists is crucial for the characterization of QGP. The motivation of this first conference, named Hot QCD Matter 2022 is to bring the community together to have a di...

arXiv (Cornell University), Apr 13, 2022

The lifting of the degeneracy between Land R-modes of massless flavors in a weakly magnetized the... more The lifting of the degeneracy between Land 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.

arXiv: High Energy Physics - Phenomenology, 2019

arXiv (Cornell University), Feb 16, 2018

arXiv (Cornell University), Jan 11, 2019

Physical review, Apr 25, 2023

arXiv (Cornell University), Nov 19, 2022

We study the thermoelectric response of a hot and magnetized QCD medium created in the noncentral... more We study 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 quarks and gluons is assimilated in the medium dependent masses of the quarks, which have been evaluated using imaginary-time formalism of thermal QCD with a background magnetic field. 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 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 transport coefficients in the weak B as the masses of chiral modes become nondegenerate. In the case of the L modes, the BGK collision term causes slight reduction in the Seebeck coefficient, while for R modes both the collision integral produces same results. Nernst coefficient gets reduced (enhanced) for L (R) chiral modes in the BGK term.

arXiv (Cornell University), Jun 6, 2016

Physics Letters B, Oct 1, 1996

arXiv (Cornell University), Nov 5, 2020

DAE Symp.Nucl.Phys., 2015

arXiv (Cornell University), Sep 11, 1998

arXiv (Cornell University), Jul 1, 2023

arXiv (Cornell University), Nov 22, 2022

Physical review, Jun 15, 2022

European Physical Journal C, Aug 16, 2006

Nuclear Physics A

International Journal of Modern Physics E

arXiv (Cornell University), Apr 13, 2022

arXiv: High Energy Physics - Phenomenology, 2019