# Measurement of the beam-helicity asymmetry in photoproduction of $\pi^{0}\eta$ pairs on carbon, aluminum, and lead

## TL;DR

This study measures the beam-helicity asymmetry in $b0\u03b7$ pair photoproduction on various nuclei, providing new experimental data and comparing it with theoretical models to understand the underlying production mechanisms.

## Contribution

First measurement of beam-helicity asymmetry in $b0\u03b7$ photoproduction on nuclear targets, extending previous free proton data and testing theoretical predictions.

## Key findings

- Photoproduction mechanism on nuclei is similar to free nucleons.
- Dominance of the $D_{33}$ partial wave with $b7\u03b4(1232)$ intermediate state.
- Results support the Mainz model predictions for nuclear targets.

## Abstract

The beam-helicity asymmetry was measured, for the first time, in photoproduction of $\pi^{0}\eta$ pairs on carbon, aluminum, and lead, with the A2 experimental setup at MAMI. The results are compared to an earlier measurement on a free proton and to the corresponding theoretical calculations. The Mainz model is used to predict the beam-helicity asymmetry for the nuclear targets. The present results indicate that the photoproduction mechanism for $\pi^{0}\eta$ pairs on nuclei is similar to photoproduction on a free nucleon. This process is dominated by the $D_{33}$ partial wave with the $\eta\Delta(1232)$ intermediate state.