Dependence of elliptic flow on number of parton degrees of freedom

We calculate the elliptic flow parameter v₂ for Au+Au collisions at s_NN=200 GeV employing the parton cascade Boltzmann approach of multiparton scatterings. Besides gluon interactions including the bremsstrahlung process, interactions with quarks are considered in an effective, but approximate, way to investigate the dependence of the collective flow on the number of parton degrees of freedom. We find that v₂ as a function of the transverse momentum p_T is sensitive to the number of parton degrees of freedom, whereas the p_T-averaged v₂ does not. When including quarks, v₂(p_T) shifts to lower p_T, the parton transverse momentum spectra become softer, and the mean parton transverse momenta decrease.