DILEPTON SIGNALS FROM QUARK-GLUON PLASMA AND FROM HADRONIC MATTER CONSISTING OF BOSONS

Lepton signals from quark-gluon plasma are compared with those from ha dronic matter consisting of pointlike bosons. When the plasma is at re st, the shapes of these two spectra differ significantly from each oth er. It is shown that hydrodynamic expansion, which is inevitable in he avy-ion collisions, smooths the spectra to such an extent that the dif ference between them is reduced to 5%. It follows that the shape of th e spectrum is determined by the hydrodynamic flow of matter rather tha n by the mechanism of pair production.