Jet quenching parameter in the gluon plasma with soft and hard components

We put forward a model of jet quenching, in which a parton traversing the quark-gluon plasma loses its energy by interacting with hard thermal gluons through the exchanges by soft gluons. The hard gluons are modeled by the Hard Thermal Loop effective theory, the soft gluons by the chromo-magnetic condensate, the interaction mechanism between the two is Landau damping of the soft gluons by the hard ones. Within such a model, we calculate the jet quenching parameter of a gluon in SU(3) quenched QCD and find that, when the temperature varies from T = Tc = 270 MeV to T = 900 MeV, the jet quenching parameter rises from ' = 0 to approximately 1.8 GeV2/fm. We compare our results with the predictions of perturbative QCD and some other nonperturbative calculations.