Transport coefficients of hot and dense hadron gas in a magnetic field: A relaxation time approach

Abstract

We estimate various transport coefficients of hot and dense hadronic matter in the presence of magnetic field. The estimation is done through solutions of the relativistic Boltzmann transport equation in the relaxation time approximation.We have investigated the temperature and the baryon chemical potential dependence of these transport coefficients. Explicit calculations are done for the hadronic matter in the ambit of hadron resonance gas model. We estimate thermal conductivity, electrical conductivity and the shear viscosity of hadronic matter in the presence of a uniform magnetic field. Magnetic field, in general, makes the transport coefficients anisotropic. It is also observed that all the transport coefficients perpendicular to the magnetic field are smaller compared to their isotropic counterpart. 12.38.Mh I. INTRODUCTIONStrongly interacting matter produced in relativistic heavy-ion collision experiments at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) give us a unique opportunity to study strong interaction in the nonperturbative regime. For a comprehensive understanding of the hot and dense QCD (quantum chromodynamics) medium produced in these experiments, transport coefficients play a crucial role. Large number of experimental data indicate the formation of quark-gluon plasma in high multiplicity heavy-ion collision experiments. Quark gluon plasma produced in the initial stage of heavy ion collision shows collective motion, undergoes subsequent space-time evolution and eventually gets chemically and the thermally equilibrated and results in a hadronic medium. Hydrodynamical modeling of the strongly interacting matter has been routinely used to study the transverse particle spectra of hadrons emanating out of the interaction region. In the context of hydrodynamical modeling, the dissipative effects can be important and the related transport coefficients e.g. shear and bulk viscosity etc can play a significant role in this hydrodynamical evolution. In various literature it has been argued that a small value of shear viscosity to entropy density ratio (η/s) can explain the flow data[1-3]. One of the remarkable achievements of the viscous hydrodynamical model is the prediction of a small value of η/s and perfect fluid behavior of the strongly interacting matter. A small value of η/s of the strongly coupled plasma produced in the heavy-ion collision is in accordance with the lower bound (KSS bound) for the same, η/s = 1 4π obtained using gauge gravity duality (AdS/CFT correspondence). Prediction of the small value of shear viscosity to entropy density ratio motivated a large number of investigations in understanding the microscopic origin of transport coefficients [3]. It is important to mention that KSS bound has been derived for a strongly coupled quantum field theory having conformal symmetry. However, QCD is not conformal and the deviation of the conformality is encoded in the bulk viscosity ζ, of the medium. [4][5][6][7][8][9][10][11][12]. Bulk viscosity encodes the confor...

Thermoelectric properties of the (an-)isotropic QGP in magnetic fields

“…And the systematic studies of shear viscosity at weak field have been done within perturbative QCD in leading log [37]. These observables have also been investigated in hadronic matter at weak magnetic field within hadron resonance gas (HRG) model [38,39]. At the strong magnetic field within the LLL approximation, electrical conductivity along the direction of magnetic field in the QGP has been estimated using diagrammatic method [40], perturbative QCD approach [41], and effective quasi-particle model [42].…”

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

“…Unlike to parallel component case, the quantitative values of QM and QFT expressions for parallel conductivity are different, which can be understood either by comparing Eqs. (32) and (25) or by minutely noticing QM (dash line) and QFT (dotted line) curves in Figs. 4(c) and (d).…”

“…Similar kind of microscopic calculations [25][26][27][28][29][30][31][32][33][34][35][36][37][38] high temperature and low density QCD matter, which can be produced in heavy ion collision (HIC) experiments like relativistic heavy ion collision (RHIC) and large hadron collider (LHC). By increasing the temperature, one can expect hadron to quark phase transition at nearly zero (net) quark/baryon density.…”

Revisiting relativistic magnetohydrodynamics from quantum electrodynamics

“…As we have presented all the field-theoretical formulas necessary for determining those parameters, one can systematically evaluate them by using, e.g., the finite-temperature perturbation theory [95][96][97][98][99][100] (see also refs. [51,52,[101][102][103][104] for the phenomenological treatments of the collisional effects) and/or the strong-coupling methods (see refs. [105][106][107][108] for holographic calculations and ref.…”