Measurement of the photon beam asymmetry in $\stackrel{P\vec}{\ensuremath{\gamma}}p\ensuremath{\rightarrow}{K}^{+}{\mathrm{\ensuremath{\Sigma}}}^{0}$ at ${E}_{\ensuremath{\gamma}}=8.5$ GeV

Measurement of the photon beam asymmetry in $\vec{γ} p \to K^{+} Σ^{0}$ at $E_{γ} = 8.5$ GeV

S. Adhikari et al. (GlueX Collaboration )

Phys. Rev. C 101, 065206 – Published 25 June 2020

Abstract

We report measurements of the photon beam asymmetry $Σ$ for the reaction $\vec{γ} p \to K^{+} Σ^{0}$ (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 $Σ$ was measured as a function of the Mandelstam variable $t$ , and a single value of $Σ$ was extracted for events produced in the $u$ channel. These are the first exclusive measurements of the photon beam asymmetry $Σ$ 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 $Σ = 1.00 \pm 0.05$ . This agrees with theoretical models that describe the reaction via the natural-parity exchange of the $K^{*}$ (892) Regge trajectory. A value of $Σ = 0.41 \pm 0.09$ is obtained for the $u$ channel integrated up to $- u = 2.0$ ( $GeV / {c)}^{2}$ .