Production and equilibration of the quark-gluon plasma with chromoelectric field and minijets

Abstract

Production and equilibration of quark-gluon plasma are studied within the color flux-tube model, at the Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider (LHC) energies. Non-Abelian relativistic transport equations for quarks, antiquarks, and gluons, are solved in the extended phase space which includes coordinates, momenta, and color. Before the chromoelectric field is formed, hard and semihard partons are produced via minijets which provide the initial conditions necessary to solve the transport equations. The model predicts that in spite of the vast difference between the RHIC and LHC incident energies, once the local equilibrium is reached, the energy densities, the number densities, and the temperatures at the two machines may not be very different from each other. The minijet input significantly alters the evolution of the deconfined matter, unless the color field is too strong. For the input parameters used here the equilibration time is estimated to be $\ensuremath{\sim}1 \mathrm{fm}$ at RHIC and $\ensuremath{\sim}0.5 \mathrm{fm}$ at LHC, measured from the instant when the two colliding nuclei have just passed through each other. The temperature at equilibration is found to be $\ensuremath{\sim}250 \mathrm{MeV}$ at RHIC and $\ensuremath{\sim}300 \mathrm{MeV}$ at LHC.