A Study of Electron Pair Production in 16 GeV/C Pi-Minus Proton Collisions

Inclusive electron-pair production in pi-minus proton collisions at 16 GeV/c was studied using a large-acceptance spectrometer equipped with Cerenkov and shower counters. A two standard-deviation signal vas observed in a region of invariant pair mass greater than 140 MeV/c2 and Feynman X between 0.15 and 0.4. The cross section, extrapolated to the full range of X, for masses greater than 140 MeV/c2, is estimated to be less than 2.5 microbarns, and the corresponding single electron to pion ratio to be less than 2.6 · 10-5. The observed electron pairs occurred mainly in the mass region 200 to 600 MeV/c2 and are believed to have originated in the primary hadronic interaction rather than the decay of secondary particles.