Search for ΔQ=−ΔS transitions in Σ-hyperon decays

Abstract

In a sample of 10⁶ Σ ⁺ hyperons we have searched for the decaysσ ⁺→ ne⁺ ν andσ ⁺→nμ ⁺ ν, which would violate theΔQ=ΔS rule. NoΣ ⁺→ne⁺ ν decay was found, whereas 313σ ⁻→ne⁻ ν decays were identified in the same film. With 90% confidence we obtain

$$\frac{{\Gamma (\sum ^ + \to ne^ + v)}}{{\Gamma (\sum ^ - \to ne^ - \bar v)}} \leqq 3.10^{ - 2} .$$

Having found two candidates for the decayσ ⁺→nμ ⁺ ν and 104Σ ⁻→nμ ⁻ ν events we obtain for the muonic mode

$$\frac{{\Gamma (\sum ^ + \to ne^ + v)}}{{\Gamma (\sum ^ - \to ne^ - \bar v)}} \leqq 3.10^{ - 2} .$$

The probability that theμ ⁺-events are simulated byσ ⁺→nπ ⁺ γ with subsequent undetectedπ ⁺→μ ⁺ ν decay is less than 4%.