Simultaneous Photoproduction of Eta and Pi0 Mesons on the Proton

The analysis of the $\gamma p\to \eta {\pi }^{0}p$ reaction has been performed using data from the GRAAL experiment. The total and differential cross sections and the beam asymmetry have been obtained from threshold up to 1.5 GeV of beam energy. The two resonances $S_{11}\left(1535\right)$ and $\Delta \left(1700\right)$ are expected to be excited in the intermediate states of this reaction. The results are used to test predictions based on the assumption that both resonances are dynamically generated from the meson-baryon interaction provided by chiral Lagrangians. The term involving the $\Delta \left(1700\right)$ excitation, followed by the decay into $\eta \Delta \left(1232\right)$, is found to be dominant.

DOI:doi.org/10.1103/PhysRevLett.100.052003