Hyperon and kaon production by 16 GeV/c negative pions on protons

Abstract

Strange particle production by 16 GeV/c negative pions in hydrogen has been studied. 60 000 pictures were taken with the CERN 32 cm hydrogen bubble chamber. The cross sections found for associated and K-K pair production are σyk= 1.32±0.15 mb, σk-k=2.21±0.25 mb. The angular distributions of the Λ0 and Σ+ hyperons show a pronounced backward peaking in the pion-proton c.m.s. The backward peak is less pronounced for Σ(−. The ratio Σ+/Σ− is 1.3 ±0.3 at production. The neutral kaons are significantly peaked forward. The average longitudinal momentum in the c.m.s. is 0.26±0.05 GeV/c along the direction of the incident pion. The average transverse momentum is small, ∼ 0.5 GeV/c, and possibly independent of the kind of particle produced. Our results indicate a higher mean value for Σ± than for Λ0 and K0. The average pion multiplicities are: for Y + K production 4.9 ±0.1, for K + -K production 4.0±0.1. The kinetic energy distributions have been compared with the predictions of the statistical theory. The contribution of nonstatistical processes is important. Different estimates give 30% as a lower limit.