Protonic decay of a Σ+ hyperon with an associated electron pair

From a stack of nuclear emulsions irradiated with K/sup -/ mesons, a protonic decay of a SIGMA /sup +/ hyperon with an associated electron pair was observed. A proton energy of 29.4 plus or minus 0.5 Mev was estimated from the range. A pi /sup 0/-meson emitted in the reaction was estimated to have an energy of 83 Mev. The emitted electron pair was determined to have an energy of 90 Mev by the open angle method and 105 Mev by the dynamics method. (C.J.G.)