First Measurement of $a^0_2(1320)$ Polarized Photoproduction Cross Section

TL;DR

This paper reports the first measurement of the differential cross section for $a_2(1320)$ meson photoproduction at 8.5 GeV, revealing insights into the production mechanism and parity exchanges using polarized photon data.

Contribution

It presents the first measurement of the $a_2(1320)$ photoproduction cross section with polarization analysis, distinguishing natural and unnatural parity exchange contributions.

Findings

First differential cross section measurement at 8.5 GeV

Separation of natural and unnatural parity exchange contributions

Provides new data for spin-exotic state searches

Abstract

We measure for the first time the differential photoproduction cross section $d\sigma/dt$ of the $a_2(1320)$ meson at an average photon beam energy of 8.5~GeV, using data with an integrated luminosity of 104~pb$^{-1}$ collected by the GlueX experiment. We fully reconstruct the $\gamma p \to \eta\pi^0 p$ reaction and perform a partial-wave analysis in the $a_2(1320)$ mass region with amplitudes that incorporate the linear polarization of the beam. This allows us to separate for the first time the contributions of natural- and unnatural-parity exchanges. These measurements provide novel information about the photoproduction mechanism, which is critical for the search for spin-exotic states.