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

Abstract

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:

$$\frac{{\Gamma \left( {\sum {^ - } \to ne^ - v} \right)}}{{\Gamma \left( {\sum {^ - } \to n\pi ^ - } \right)}} = (1.09 \pm 0.06) x 10^{ - 3} .$$