Evidence for a narrow structure at W∼1.68 GeV in η photoproduction off the neutron

New results on quasi-free η photoproduction on the neutron and proton bound in a deuteron target are presented. The γn→ηn quasi-free cross section reveals a bump-like structure which is not seen in the cross section on the proton. This structure may signal the existence of a relatively narrow (M∼1.68GeV, Γ⩽30MeV) baryon state.