2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/190581We study analytically the medium-induced energy loss of a high energy parton passing through a finite size QCD plasma, which is expanding longitudinally according to Bjorken's model. We extend the BDMPS formalism already applied to static media to the case of a quark which hits successive layers of matter of decreasing temperature, and we show that the resulting radiative energy loss can be as large as 6 times the corresponding one in a static plasma at the reference temperature $T = T (L)$, which is reached after the quark propagates a distance $L$.19 pages, REVTEX. 1 figureHigh Energy Physics - Phenomenologytext