Speaker
Description
Hadron photoproduction is an essential experimental tool that gives important information on the spectroscopic and structural nature of hadrons. At large photon energies and low invariant mass of the $\pi\pi$ subsystem, the differential cross section is dominated by the prominent $\rho(770)$ resonance. At forward angles, the production of the $\rho$ is mostly diffractive, and exhibits a hierachy of partial waves which may be interpreted as the result of approximate s-channel helicity conservation (SCHC). Regge formalism captures these reaction properties in terms of the Pomeron exchange. In this talk, we present a theoretical model of two-pion photoproduction which encodes the prominent $\rho$ resonance and the expected leading background contribution coming from the so-called "Deck" or "Drell-Soding" mechanism. After fitting this model to a subset of moments, we compare our predictions for the angular moments with the CLAS data. We observe the apparent breakdown of SCHC at larger four momentum transfers, and extract the $t$- dependence of the Regge amplitude residue function for subdominant exchanges.
