Eur. Phys. J. A (2019) 55: 220
https://doi.org/10.1140/epja/i2019-12907-y

Regular Article - Theoretical Physics

Thermomagnetic properties and Bjorken expansion of hot QCD matter in a strong magnetic field

Department of Physics, Indian Institute of Technology Roorkee, 247667, Roorkee, India

^* e-mail: srath@ph.iitr.ac.in

Received: 8 February 2019
Accepted: 3 October 2019
Published online: 21 November 2019

Abstract

In this work we have explored the effect of a strong homogeneous magnetic field on the thermodynamic and magnetic properties of hot QCD matter, which is in turn used in the form of equation of state to explore the effect of the same on the hydrodynamic expansion of the matter produced in the ultrarelativistic heavy ion collisions. For that purpose, we have first computed the quark and gluon contributions to the free energy up to one loop in the strong magnetic field in hard thermal loop approximation with two hard scales, temperature and magnetic field for gluon and quark degrees of freedom, respectively, and we have found that the speed of sound gets enhanced due to the presence of a strong magnetic field. Secondly, we have studied the magnetic properties of the matter, where magnetization is found to increase linearly with the magnetic field, implying paramagnetic nature, whereas magnetization is observed to increase slowly with temperature. Finally, we have studied the hydrodynamic evolution of matter in the Bjorken boost-invariant picture with the above-mentioned paramagnetic equation of state as an input and have noticed that energy density evolves faster than the one in the absence of a strong magnetic field, i.e. cooling becomes faster, which is a clear manifestation of the enhancement of the speed of sound. This observation could have implications on the heavy-ion phenomenology, viz. dilepton and photon productions at the early stages of the collisions.