Inclusive photoproduction of strange baryons at 20 GeV

Cross sections are presented for the inclusive photoproduction of $K_S^0$, Λ, Λ¯, ${\Xi }^{\mathrm{-}}$, Ξ¯${\mathrm{}}^{\mathrm{-}}$, ${\Sigma }^0$, and ${\Sigma }^{\mathrm{*}\pm }$(1385) at 20 GeV. An upper limit to ${\Omega }^{\mathrm{-}}$ production is also given. The data come from 284 000 hadronic events photoproduced in the SLAC 1-m hydrogen-bubble-chamber hybrid facility exposed to a nearly monochromatic, polarized 20-GeV backscattered photon beam. A comparison of the $K_S^0$, Λ, Λ¯, and ${\Xi }^{\mathrm{-}}$ rates per inelastic event to ${\pi }^{\pm }$p data show that γp rates are consistent with being higher than the ${\pi }^{\pm }$p rates, providing evidence of an ss¯ component of the photon. The pair cross sections for $K_S^0$ $K_S^0$, $K_S^0$Λ, $K_S^o$Λ¯, and ΛΛ¯ are presented. The $x_F$ distributions of the Λ, Λ¯, and ${\Xi }^{\mathrm{-}}$ are compared to a quark-diquark fusion model, giving information on strange-baryon photoproduction mechanisms.