MT SCALING IN DILEPTON SPECTRUM AS A SIGNATURE FOR QUARK-GLUON PLASMA

In general, the spectrum of lepton pairs produced in nuclear reactions depends on both invariant mass and momentum. But under a few reasonable assumptions on the time evolution of the system, we show that once the quark-gluon plasma is created in ultrarelativistic heavy ion collisions, the observed dilepton spectrum between the phi and J/psi peak becomes dependent essentially only on its transverse mass M(T) and thus shows M(T) scaling. This scaling will not be observed if the quark-gluon plasma is not created in collisions.