Hyperon Production at Hermes

A brief overview of hyperon production at HERMES is presented. The data were accumulated by the HERMES spectrometer using the 27.5 GeV longitudinally polarized HERA positron beam and the unpolarized (polarized) internal gas target. Semi-inclusive reactions with polarized Λ⁰ hyperon in the final state have been studied. At the average fractional Λ energy < z > = 0.45, the longitudinal spin transfer coefficient to the Λ⁰ hyperon is found to be 0.04 ± 0.08(stat) ± 0.03(syst). The HERMES experiment has measured the transverse polarization of the Λ and bar Λ hyperons produced inclusively in quasi-real photon-nucleon interaction. Inclusively produced Σ⁰, Σ*⁺, Σ*^-, and Ξ^- hyperons and their antiparticles have also been detected by the HERMES spectrometer.