A study of inclusive photoproduction of hyperons and antihyperons in the range of 20 to 70 GeV

Abstract Results are presented on inclusive photoproduction in hydrogen of Σ 0 , Σ 1385 ± , Ξ − 0 , and their antiparticles for incident energies between 20 and 70 GeV. Hyperons and antihyperons are mainly measured in the kinematical range of central and forward production ( x F > −0.3). We find the cross-section ratios σ(Σ 1385 + ) σ(Σ 1385 − ) = 1.4 ± 0.1 , σ( Σ 1385 + ) σ( Σ 1385 − ) = 1.3 ± 0.2 and an antiparticle/particle ratio of about 0.3 for the three sigma states. The results suggest an important role of the valence quarks of both the beam projectile and target in the production process in qualitative agreement with current ideas of quark fusion models. The inclusive production of Σ 1385 ± is also observed in a small subsample of the events containing Λ Λ pairs. The x F distribution of Λ ( Λ ) in Λ Λ events as well as those in Λ p ( p Λ ) is the same as those in single Λ( Λ ) inclusive events. Weak signals in the K − p π + and Λπ + π + π − mass spectra are observed around a mass of 2.26 GeV.