First measurement of direct photoproduction of the $a_2(1320{)}^0$ meson on the proton

Abstract

We present the first measurement of the exclusive reaction $\gamma p\to a_2(1320{)}^{0}p$ in the photon energy range $3.5$-$5.5$ GeV and four-momentum transfer squared $0.2<-t<2.0$ GeV${}^2$. Data were collected with the CEBAF Large Acceptance Spectrometer at the Thomas Jefferson National Accelerator Facility. The neutral $a_2$ resonance was detected by measuring the reaction $\gamma p\to {\pi }^0\eta p$ and reconstructing the ${\pi }^0\eta$ invariant mass. The differential cross section $d\sigma /dt$ was extracted at different beam energies in each $-t$ bin. The most prominent feature of the differential cross section is a dip at $-t\simeq 0.55$ GeV${}^2$. This can be well described in the framework of Regge phenomenology, where the exchange degeneracy hypothesis predicts a zero in the reaction amplitude for this value of the four-momentum transfer.

arXiv commentVersion accepted for publication in PRC, "Rapid Communications" section

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Cited by in corpus (4)

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• Photoproduction of the $f_2(1270)$ meson using the CLAS detector
• High-energy ${\eta }^{(\prime )}\pi$ photoproduction and the nature of exotic waves