Non-uniform chiral phase in effective chiral quark models

We analyze the phase diagram in effective chiral quark models (the Nambu-Jo na-Lasinio model, the sigma-model with quarks) and show that at the mean-fi eld level a phase with a periodically-modulated chiral fields separates the usual phases with broken and restored chiral symmetry. A possible signal o f such a phase is the production of multipion jets travelling in opposite d irections, with individual pions having momenta of the order of several hun dred MeV. This signal can be interpreted in terms of disoriented chiral con densates. (C) 2000 Elsevier Science B.V. All rights reserved.