Optimal reactions for the search for π0→e+e-

Abstract

The authors examine various reactions in which one might search for pi ⁰ to e⁺e^-; apart from the problem of the low branching ratio, the most serious observational difficulties arise from the competition of intermediate virtual photon states of close to the pion mass. They show that the obvious choice of pi ^-p to pi ⁰n at threshold is an unfavourable pion source but that the same reaction in the Delta (1236) resonance region seems currently to offer the best opportunity; it is analysed in detail K⁺ to pi ⁺ pi ⁰ seems the most hopeful alternative.