Form of the Interaction in Lambda-Hyperon Beta Decay

The form of the ${\Lambda }_{\beta }$-decay interaction was studied by using lambdas produced by stopping $K^{-}$ mesons in the Berkeley 30-in. propane-freon bubble chamber. A selected sample of 59 ${\Lambda }_{\beta }$ decays were analyzed in the $\Lambda$ rest system, and 50 of these were further studied in the laboratory system. The results show that a pure tensor interaction can be ruled out with 98% confidence, and for mixtures of vector and axial vector, $\left|\frac{C_A}{C_V}\right|$ is greater than 0.7 with 95% confidence. Scalar and pseudoscalar, either alone or with small admixtures of tensor, cannot be ruled out. Pure axial-vector and $V\pm A$ are consistent with the data.