Study of prompt e/sup +/e/sup -/, eta/sup 0/, and. omega. /sup 0/ production in low-energy p-barp annihilations

A study of prompt e/sup +/e/sup -/ production has been made using the Argonne 12-foot bubble chamber exposed to a low-energy p-bar beam. We found eleven annihilation events with e/sup +/e/sup -/ pairs of invariant mass greater than the ..pi../sup 0/ mass. The background to direct e/sup +/e/sup -/ pair production comes mainly from eta/sup 0/ ..-->.. ..gamma..e/sup +/e/sup -/ and ..omega../sup 0/ ..-->.. ..pi../sup 0/e/sup +/e/sup -/ Dalitz pairs. To determine these backgrounds, we have measured the inclusive eta/sup 0/ and ..omega../sup 0/ production rates using externally converted ..gamma.. rays. We find ..omega../sup 0//..pi../sup 0/=0.20 +- 0.07 and eta/sup 0//..pi../sup 0/<0.11 at the 90% confidence level. The (eta/sup 0/+..omega../sup 0/) Dalitz background plus other small backgrounds yield 7.0/sup +4.4//sub -3.0/ events. The remaining events yield a 90%-confidence-level upper limit for the ratio of prompt e/sup +/e/sup -/ pairs to ..pi../sup 0/ production of 4 x 10/sup -5/.