Σ±Lifetime and the Branching RatioBΣ+≡(Σ+→π++n)(Σ+→All)

Abstract

Using 11 000 charged $\Sigma$'s produced from $K^{-}+p\to {\Sigma }^{\pm }+{\pi }^{\mp }$ interactions taking place in the 30-in. Columbia-BNL hydrogen bubble chamber, we have determined the ${\Sigma }^{\pm }$ lifetimes and the branching ratio $B_{{\Sigma }^{+}}\equiv \frac{({\Sigma }^{+}\to {\pi }^{+}+n)}{({\Sigma }^{+}\to \mathrm{all})}$. By means of a least-squares fit to the differential decay distributions for the in-flight sigma decays, the following values were obtained: ${\tau }_{{\Sigma }^{+}}=(0.830\mathrm{}\pm 0.018)\times {10}^{-10\mathrm{}}$ sec, ${\tau }_{{\Sigma }^{-}}=(1.666\mathrm{}\pm 0.026)\times {10}^{-10\mathrm{}}$ sec, and $B_{{\Sigma }^{+}}=0.46\mathrm{}\pm 0.02$.