Primakoff effect in η-photoproduction off protons

Abstract

We analyse data on forward η-meson photoproduction off a proton target and extract the η→γγdecay width utilizing the Primakoff effect. The hadronic amplitude that enters into our analysis is strongly constrained because it is fixed from a global fit to available γp→pηdata for differential cross-sections and polarizations. We compare our results with present information on the two-photon η-decay from the literature. We provide predictions for future PrimEx experiments at Jefferson Laboratory in order to motivate further studies. © 2010 SIF, Springer-Verlag Berlin Heidelberg.