  We present a study of the properties of the collective modes of a system
composed by a thermalized quark-gluon plasma traversed by a relativistic jet of
partons. We find that when the jet traverses the system unstable gauge field
modes are excited and grow on very short time scales. The aim is to provide a
novel mechanism for the description of the jet quenching phenomenon, where the
jet crossing the plasma loses energy exciting colored unstable modes. In order
to simplify the analysis we employ a linear response approximation, valid for
short time scales. We assume that the partons in the jet can be described with
a tsunami-like distribution function, whereas we treat the quark-gluon plasma
employing two different approaches. In the first approach we adopt a Vlasov
approximation for the kinetic equations, in the second approach we solve a set
of fluid equations. In both cases we derive the expressions of the dispersion
law of the collective unstable modes and compare the results obtained.

High Energy Physics - Phenomenology;Nuclear Theory