Polarization and weak decays of Λ hypernuclei produced by the (π+, K+) reaction on 12C

Abstract Non-mesonic weak-decay protons (NM-p) and mesonic weak-decay pions (M- π ) from Λ produced by the ( π + , K + ) reaction on 12 C have been measured. NM-p from the 11 Λ B ( 5 2 + ) produced through the proton-unbound states in 12 Λ C and NM-p and M- π associated with the quasi-bound region ( E x ≈ 20 MeV) in 12 Λ C show finite asymmetries of A 1 = − 0.20 to − 0.35 with respect to the reaction plane. These results indicate finite polarizations of the relevant Λ-hypernuclei and asymmetric NM weak decays.