First Measurement of $a_2^0(1320)$ Polarized Photoproduction Cross Section

Abstract

We measure for the first time the differential photoproduction cross section $d\ddot{I}ƒ/dt$ 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 ${\hat{I}}^{3}p\to \hat{I}\cdot \ddot{I}{€}^{0}p$ 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.

8 pages, 4 figures plus supplemental material