The hadronization cross section in a quark plasma at finite temperature and density is calculated in the framework of the Nambu–Jona-Lasinio model with explicit chiral symmetry breaking. In contrast to the familiar temperature effect, the quark plasma at high density begins to hadronize suddenly. It leads to a sudden and strong increase of final state pions in relativistic heavy ion collisions which may be considered as a clear signature of chiral symmetry restoration.

• Received 11 January 2000

DOI:https://doi.org/10.1103/PhysRevC.62.054901