Measurement of the beam asymmetry Σ for π^0 and η photoproduction on the proton at E sub γ=9 GeV

Publication Information

• H. Al Ghoul et al. [GlueX Collaboration], Phys. Rev. C95, 042201 (2107), DOI:10.1103/PhysRevC.95.042201.
• arXiv:1701.08123 [nucl-ex] (2017).
• HEPData.

Abstract

We report measurements of the photon beam asymmetry Σ for the reactions γ⃗p→π⁰p and γ⃗p→ηp from the GlueX experiment using a 9 GeV linearly-polarized, tagged photon beam incident on a liquid hydrogen target in Jefferson Lab's Hall D. The asymmetries, measured as a function of the proton momentum transfer, possess greater precision than previous π⁰ measurements, and are the first η measurements in this energy regime. The results are compared with theoretical predictions based on t-channel, quasi-particle exchange and constrain the axial-vector component of the neutral meson production mechanism in these models.

Figures and captions

Caption	Figures
(a) Photon beam intensity versus energy as measured by the pair spectrometer (not corrected for instrumental acceptance). (b) Photon beam polarization as a function of beam energy, as measured by the triplet polarimeter, with data points offset horizontally by ±0.015 GeV for clarity.	pdf