Ballistic diffusion of heavy quarks in the early stage of relativistic heavy ion collisions at RHIC and LHC

Abstract

We study the diffusion of charm quarks in the early stage of high energy nuclear collisions at the RHIC and the LHC. The main novelty of the present study is the introduction of the color current carried by the heavy quarks that propagate in the evolving Glasma (Ev-Glasma), that is responsible of the energy loss via polarization of the medium. We compute the transverse momentum broadening, ${\sigma }_p$, of charm in the pre-thermalization stage, and the impact of the diffusion on the nuclear modification factor in nucleus-nucleus collisions. The net effect of energy loss is marginal in the pre-thermalization stage. The study is completed by the calculation of coordinate spreading, ${\sigma }_x$, and by a comparison with Langevin dynamics. ${\sigma }_p$ in Ev-Glasma overshoots the result of standard Langevin dynamics at the end of the pre-hydro regime. We interpret this as a result of memory of the color force acting on the charm quarks that implies ${\sigma }_p\propto t^2$. Moreover, ${\sigma }_x\propto t^2$ in the pre-hydro stage shows that the charm quark in the Ev-Glasma is in the regime of ballistic diffusion.

12 pages, 5 figures. In V2 we have corrected the presentation on how color charges are initialized in the code. A few clarifying comments have been added, to justify the use of the SU(2) color group, and to improve the presentation of the Langevin equation with the nonlocal dissipative kernel. V2 is the version accepted for publication on Phys. Rev. D

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Cited by in corpus (11)

• Simulating jets and heavy quarks in the Glasma using the colored particle-in-cell method
• Transport of hard probes through glasma
• Memory effects on energy loss and diffusion of heavy quarks in the quark-gluon plasma
• Dynamics of Hot QCD Matter -- Current Status and Developments
• Energy Loss Versus Energy Gain of Heavy Quarks in a Hot Medium
• The impact of glasma on heavy flavor azimuthal correlations and spectra
• Persistent nonequilibrium effects in generalized Langevin dynamics of nonrelativistic and relativistic particles
• Dynamics of heavy flavour in a weakly magnetized hot QCD medium
• Anomalous diffusion of the heavy quarks through the fractional Langevin equation
• Nonperturbative heavy quark diffusion coefficients in a weakly magnetized thermal QCD medium
• Elliptic flow of charm quarks produced in the early stage of pA collisions