Double Polarization Observables in η Electroproduction Original Research Article

A new measurement of beam-recoil double-polarization observables in η electroproduction at the A1 collaboration at MAMI is presented. The energy region of the S11(1525) resonance was covered at a four-momentum transfer of Q2=0.1 GeV2/c2. It turned out, that the usual interpretation of the reaction mechanism via S11 and D13 resonance fails to explain the relative phase between the corresponding multipole amplitudes tested by this experiment, while the new data are still in good agreement with previous measurements.