Measurement of thesum {^ - to ne^ - bar v} rate and search for ΔQ=−ΔS transitions in Σ+→ne + ν decay

In a bubble chamber experiment about 2×10⁶ Σ ^±-decays have been measured to separateΣ ^±→ne^±¯ν events from the two-body modes. NoΣ ⁺ →ne ⁺ ν event was found whereas 607Σ ^?→ne^?¯ν decays could be identified. The data yield for the ΔQ=?ΔS decay an upper limit: $$frac{{Gamma left( {sum {^ + } to ne^ + v} right)}}{{Gamma left( {sum {^ - } to ne^ - v} right)}}< 1.9 x 10^{ - 2} (90% confidence level)$$ and the branching ratio: $$frac{{Gamma left( {sum {^ - } to ne^ - v} right)}}{{Gamma left( {sum {^ - } to npi ^ - } right)}} = (1.09 pm 0.06) x 10^{ - 3} .$$