2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/45689Within the framework of a dynamical and physically transparent model developed earlier, we study the time evolution of various quark flavours in the baryon-free region in ultrarelativistic heavy ion collisions. We show that even under optimistic conditions, the quark-gluon system fails to achieve chemical equilibrium.6 pages LATEX, 1 fig. (non-postscript) available on requestHigh Energy Physics - Phenomenologytext