Thermalization in ultrarelativistic nuclear collisions. II. Entropy production and energy densities at the BNL Relativistic Heavy Ion Collider and the CERN Large Hadron Collider

Abstract

The dynamics of partons in ultrarelativistic $^{197}\mathrm{Au}$+$^{197}\mathrm{Au}$ collisions in the future collider experiments at the BNL Relativistic Heavy Ion Collider and the CERN Large Hadron Collider during the first 3 fm/c is simulated in full six-dimensional phase space within a parton cascade model to compute the entropy production and the space-time-dependent energy densities, temperatures, etc., in the central collision region. The partons' evolution from preequilibrium towards the formation of a thermalized quark-gluon plasma is investigated and compared to the Bjorken scenario. Moreover, an equation of state is extracted together with initial conditions for the further hydrodynamical space-time evolution of the matter. For central $^{197}\mathrm{Au}$+$^{197}\mathrm{Au}$ collisions with $\sqrt{s}=200\ensuremath{-}6300A$ GeV the predictions for the energy densities and associated temperatures at $t=3$ fm/c after the first instant of the collisions are $\ensuremath{\varepsilon}=15\ensuremath{-}31$ GeV/${\mathrm{fm}}^{3}$ and $T=297\ensuremath{-}343$ MeV, respectively. The multiplicity of final pions from the plasma is estimated from the amount of entropy produced, yielding a huge $\frac{d{N}^{(\ensuremath{\pi})}}{\mathrm{dy}\ensuremath{\simeq}1900\ensuremath{-}3400}$.