Soft photon emission as a sign of sharp transition in quark-gluon plasma
  Photon emission arising in the course of transition between the states of quark-gluon and hadron plasma has been considered. Single-photon distributions and two-photon correlations in central rapidity region have been calculated for heavy ion collisions at high energies. It has been found that opposite side two-photon correlations can serve as a sign of sharp transitions between the states of strongly interaction matter. 
I.V.Andreev (Lebedev Physical Institute, Moscow, Russia)