Decay Asymmetry of $Σ^{+}$ and $Λ^{0}$ Hyperons

Counter techniques have been used to measure decay asymmetries for polarized

Λ^{0}

and

Σ^{+}

hyperons. The

Σ^{+}

hyperons were produced by 1.13-Bev/c

π^{+}

in the reaction

π^{+} + p \to Σ^{+} + K^{+}

. The

Λ^{0}

hyperons were produced by 1.00-Bev/c

π^{+}

in the reaction

π^{+} + d \to K^{+} + Λ^{0} + p

. The asymmetry for each hyperon decay mode was measured with a counter arrangement which detected separately charged pions and

γ

rays from neutral pions. The protons from the hyperon decay were also detected to confirm the identification of the decay modes. The product

α \bar{P}

was measured, where

α

is the asymmetry parameter and

\bar{P}

is the average polarization of the hyperon. The following results were obtained for the various decay modes:

Σ^{+} \to π^{+} + n, α \bar{P} = + 0.03 \pm 0.08;

Σ^{+} \to π^{0} + p, α \bar{P} = + 0.75 \pm 0.17;

Λ^{0} \to π^{-} + p, α \bar{P} = + 0.55 \pm 0.06;

Λ^{0} \to π^{0} + n, α \bar{P} = + 0.60 \pm 0.13;

The results for

Σ^{+}

are fitted to the triangular relationship demanded by the

| Δ I | = \frac{1}{2}

rule, and absolute values for the asymmetries of

Σ^{\pm}

decay are predicted. The ratio

\frac{α (Λ^{0} \to π^{0} + n)}{α (Λ^{0} \to π^{-} + p)} = + 1.10 \pm 0.27

is in agreement with the value +1.00 predicted by the

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Decay Asymmetry ofΣ+andΛ0Hyperons