Measurement of the Photon Beam Asymmetry in γ p K+0 at Eγ = 8.5 GeV

Abstract

We report measurements of the photon beam asymmetry for the reaction γ p K+0(1193) using the GlueX spectrometer in Hall D at Jefferson Lab. Data were collected using a linearly polarized photon beam in the energy range of 8.2-8.8 GeV incident on a liquid hydrogen target. The beam asymmetry was measured as a function of the Mandelstam variable t, and a single value of was extracted for events produced in the u-channel. These are the first exclusive measurements of the photon beam asymmetry for the reaction in this energy range. For the t-channel, the measured beam asymmetry is close to unity over the t-range studied, -t=(0.1-1.4)~(GeV/c)2, with an average value of = 1.00 0.05. This agrees with theoretical models that describe the reaction via the natural-parity exchange of the K*(892) Regge trajectory. A value of = 0.41 0.09 is obtained for the u-channel integrated up to -u=2.0~(GeV/c)2.