Heavy flavour Langevin diffusion with the chromo-electromagnetic field fluctuations in the quark–gluon plasma

Abstract

The chromo-electromagnetic field is produced due to the motion of partons in a quark–gluon plasma created by relativistic heavy-ion collisions. The fluctuations in the produced chromo-electromagnetic field are important, since they cause heavy quarks to gain energy in the low velocity limit. We study the effect of such fluctuations on heavy quark diffusion in quark–gluon plasma within the framework of Langevin dynamics under the background matter described by the ($3+1$)-dimensional relativistic viscous hydrodynamics. Theoretical calculations of the nuclear modification factor ($R_{AA}$) of heavy mesons (D and B mesons), with the effect of these fluctuations, are compared with experimental measurements in Au–Au collisions at $\sqrt{s_{NN}} = 200$ GeV by the STAR experiment at the BNL Relativistic Heavy Ion Collider (RHIC) and Pb–Pb collisions at $\sqrt{s_{NN}} = 2.76$ and 5.02 TeV by the ALICE and CMS experiments at the CERN Large Hadron Collider (LHC). In addition to that, the elliptic flow ($v_2$) of D-meson has been calculated in the same framework for Pb–Pb collisions at $\sqrt{s_{NN}} = 2.76$ and compared with ALICE measurements. We find a significant effect of these fluctuations in describing the measured $R_{AA}$ and $v_2$ of heavy flavour mesons at both RHIC and LHC energies.