Differential Cross Sections for gamma + p --> K+ + Y for Lambda and Sigma0 Hyperons

Abstract

High-statistics cross sections for the reactions gamma + p --> K^+ + Lambda and gamma + p --> K^+ + Sigma^0 have been measured using CLAS at Jefferson Lab for center-of-mass energies W between 1.6 and 2.53 GeV, and for -0.85 < cos theta_{K^+}^{c.m.}< +0.95. In the K^+ Lambda channel we confirm a resonance-like structure near W=1.9 GeV at backward kaon angles. The position and width of this structure change with angle, indicating that more than one resonance is likely playing a role. The K^+ Lambda channel at forward angles and all energies is well described by a t-channel scaling characteristic of Regge exchange, while the same scaling applied to the K^+ Sigma^0 channel is less successful. Several existing theoretical models are compared to the data, but none provide a good representation of the results.