Determination of the Σ^± → Λe ^±ν decay parameters

Abstract

From about 6×10⁶ stoppingK ⁻-meson reactions in the Saclay 80 cm hydrogen bubble chamber 70Σ ⁻→Λe⁻¯ν and 11Σ⁺→Λe⁺ν decays have been identified. The ratio of the vector to axial vector coupling constant has been determined,f ₁/g ₁=−0.22±0.28, consistent with the predictionf ₁=0 of the CVC-theory. The branching ratios for the two decay modes are,Γ(Σ ⁻→Λe⁻ν)/Γ(Σ⁻→ all modes)=(0.69±0.12). 10⁻⁴,Γ(Σ⁺→Λe⁺ν)/Γ(Σ⁺→ all modes)=(0.29±0.10). 10⁻⁴. The ratio, Γ(Σ⁺→Λe⁺)/Γ(Σ⁻→Λe⁻v)=0.69±0.18, agrees with the phase space ratio, 0.61, therefore a theory that includes no second class currents is consistent with the data.