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

In a bubble chamber experiment about 2×106Σ±-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: $$\frac{{\Gamma \left( {\sum {^ - } \to ne^ - v} \right)}}{{\Gamma \left( {\sum {^ - } \to n\pi ^ - } \right)}} = (1.09 \pm 0.06) x 10^{ - 3} .$$