First measurement of direct photoproduction of the a2(1320)0 meson on the proton

We present the first measurement of the reaction γp→a2(1320)0p in the photon energy range 3.5-5.5GeV and four-momentum transfer squared 0.2<-t<2.0GeV2. Data were collected with the CEBAF Large Acceptance Spectrometer detector at the Thomas Jefferson National Accelerator Facility. The a2 resonance was detected by measuring the reaction γp→π0ηp and reconstructing the π0η invariant mass. The most prominent feature of the differential cross section is a dip at-t≈0.55GeV2. This can be 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.