Measurement of the helicity-dependent total cross-section for the gamma n -> p pi(-)pi(0) reaction

The helicity dependence of the total cross-section for the gamma n -> p pi(-)pi(0) reaction has been measured for the first time at incident photon energies from 450 to 800MeV. The measurement was performed with the large-acceptance detector DAPHNE at the tagged photon beam facility of the MAMI accelerator in Mainz. Both the measured unpolarized and the helicity-dependent observables are not well described by the existing theoretical models.