Elliptic flow and nuclear modification factor within a partonic transport model

摘要

The partonic transport approach BAMPS (Boltzmann Approach to Multi-Parton Scatterings) aims to describe microscopically the partonic phase of ultra-relativistic heavy-ion collisions by perturbative quantum chromodynamics. To this end, it numerically solves the 3+1D Boltzmann equation by allowing interactions among all parton species: both elastic 2 -> 2 and inelastic 2 <-> 3 collisions for gluons as well as quarks. For the inelastic collisions, we employ the improved Gunion-Bertsch matrix element, which cures problems of the original Gunion-Bertsch result in characteristic regions of the phase space. Based on extensive numerical calculations, the improved matrix element agrees well with the exact pQCD calculation. By employing the improved GB matrix element together with a running coupling evaluated at the microscopic scale, we present our recent results for the suppression of high p(t) particles as well as the collectivity of the bulk medium and compare them to LHC data of the nuclear modification factor R-AA and the elliptic flow v(2). Furthermore, we present studies of R-AA for different hadron species and the momentum imbalance A(J) of reconstructed jets. (C) 2014 Elsevier B.V. All rights reserved.