# Measurement of the beam asymmetry $\Sigma$ for $\pi^0$ and $\eta$ photoproduction on the proton at $E_\gamma = 9$ GeV

## TL;DR

This paper presents precise measurements of photon beam asymmetries for $b5^0$ and $b7$ photoproduction on protons at 9 GeV, providing new data to test theoretical models of meson production mechanisms.

## Contribution

First measurements of $b7$ asymmetry at this energy, with improved precision for $b5^0$, constraining theoretical models of meson photoproduction.

## Key findings

- Enhanced precision in $b5$ asymmetry measurements
- First $b7$ asymmetry data at 9 GeV
- Constraints on axial-vector components in production models

## Abstract

We report measurements of the photon beam asymmetry $\Sigma$ for the reactions $\vec{\gamma}p\to p\pi^0$ and $\vec{\gamma}p\to p\eta $ 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 $\pi^0$ measurements and are the first $\eta$ 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.