  The Nambu Jona-Lasinio Lagrangian offers an explication of the seemingly
contradictory observations that a) the energy loss in the entrance channel of
heavy ion reactions is not sufficient to thermalize the system and that b) the
observed hadron cross sections are in almost perfect agreement with
hydrodynamical calculations. According to this scenario, a critical opacity
develops close to the chiral phase transition which equilibrates and hadronizes
the expanding system very effectively. It creates as well radial flow and, if
the system is not isotropic, finite $v_2$ values.

High Energy Physics - Phenomenology