THE LANDAU-POMERANCHUK EFFECT AND SOFT LEPTON-PAIR PRODUCTION IN HEAVY-ION COLLISIONS

A detailed discussion of the properties of low mass dilepton productio n in heavy-ion collisions is presented taking into account the Landau- Pomeranchuk suppression effect in an expanding medium. Our results are then compared with non-thermal Dalitz eta-decay into dileptons. It is shown that at high initial temperature tau approximately 0.9 GeV and short thermalization time tau0 approximately 0.07 fm the properties of a quark-gluon plasma in heavy-ion collisions would be determined by m easuring the p(t) spectra of low mass dilepton pairs. For lower initia l temperatures one needs to subtract the background from Dalitz decays in order to extract a quark-gluon plasma signal.