Direct observation of a ρ decay of the D13(1520) baryon resonance -: art. no. 052001

The reaction gammap --> pi (+)pi (o)n has been measured at MAMI for photon energies up to 820 MeV. Invariant mass spectra of the particles in the final state (pi (+)n), (pi (o)n), (pi (+)pi (o)) have been determined for several bins of incident photon energy. Differences in pi (+)pi (o) and simultaneously measured pi (o)pi (o) invariant mass distributions are assigned to a rho branch of the D-13(1520) nucleon resonance.