Concerning fore-aft asymmetry in Λ0-decay

A sample of Λ0-hyperons recorded in photographic emulsions has been identified by estimating the energy release,Q, in their decay. The observations have then been used to study fore-aft asymmetry in the decay of the Λ0-hyperon. The energy spectrum of Λ0-hyperons has allowed the fractions produced (a), by strong interactions: K−+ Open image in new window → →Λ0+π, Σ+ Open image in new window →Λ0+ Open image in new window ; and (b), by radiative decay: Λ0→Λ0+γ, to be separately distinguished. In sample (a), the observed value of the quantityα\(\bar p\)=0.23±0.24, and ofNf/Nb=25/27, a result consistent with an isotropic distribution. For sample (b), the distribution is asymmetric,α\(\bar p\)=1.12±0.27 andNf/Nb=33/9. Thus Λ0-hyperons produced by radiative decay display longitudinal polarization, as expected. A scanning procedure has been adopted which eliminates any possible contribution of spurious fore-aft asymmetry due to scanning bias.