Dileptons as a probe of excited nuclear matter

Abstract

The general features of dilepton production from nucleon–nucleon and nucleus–nucleus collisions are discussed. Estimates are made of the thermal production rates arising from incoherent nucleon–nucleon scattering and from two-pion annihilation. It may be possible to infer the pion dispersion relation in hot, dense nuclear matter by measuring the invariant mass distribution of back-to-back electrons and positrons in the center of mass frame in high energy nucleus–nucleus collisions. Comparison with recent data on p + Be → e+e−X at 4.9 GeV from the Bevalac is made.