Eta photoproduction on the proton for photon energies from 0.75 to 1.95 GeV

Phys Rev Lett. 2002 Nov 25;89(22):222002. doi: 10.1103/PhysRevLett.89.222002. Epub 2002 Nov 12.

Abstract

Differential cross sections for gammap-->etap have been measured with tagged real photons for incident photon energies from 0.75 to 1.95 GeV. Mesons were identified by missing mass reconstruction using kinematical information for protons scattered in the production process. The data provide the first extensive angular distribution measurements for the process above W=1.75 GeV. Comparison with preliminary results from a constituent quark model support the suggestion that a third S11 resonance with mass approximately 1.8 GeV couples to the etaN channel.