Measurement of the photon beam asymmetry in (γ)over-right-arrowp → K+Σ0 at Eγ=8 . 5 GeV

We report measurements of the photon beam asymmetry Sigma for the reaction (gamma) over right arrowp -> K+Sigma(0) (1193) using the GlueX spectrometer in Hall D at Jefferson Lab. Data were collected by 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 Sigma was measured as a function of the Mandelstam variable t, and a single value of Sigma was extracted for events produced in the u channel. These are the first exclusive measurements of the photon beam asymmetry Sigma 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 Sigma = 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 Sigma = 0 .41 +/- 0 .09 is obtained for the u channel integrated up to -u = 2 .0 (GeV/c)(2).