Polarization of Λ⁰ hyperons in K^-p interactions

Abstract

The polarization of the Λ⁰ hyperon produced inK ^- p interactions at 110 GeV/c shows a strong dependence on the transverse momentum p _t of the Λ⁰ and no significant dependence on x _F . The polarization for large p _t is negative in the proton hemisphere and positive in the kaon hemisphere. In theproton hemisphere it is compared with the results of other K ^- p experiments at lower energies as well as with reactions induced by p, p^-, π⁺, π^- and K ⁺. The comparison is performed separately for K ^- p→Λ ⁰ KK+pions and K ^- p→Λ ⁰+pions showing an analogous behaviour in the former channel. In the kaon hemisphere the comparison with other K ^- p experiments at lower energy shows a p _t -dependence of the Λ⁰ polarization which changes with energy. The experimental results are discussed in terms of current quark models and of the Mueller-Regge phenomenology. The model predictions reproduce the trend of the data qualitatively well but fail in describing some details.