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. |
