Single-Energy Partial Wave Analysis for $\pi^0$ Photoproduction on Proton with Fixed-$t$ Analyticity Imposed.

High precision data of the $\gamma p \to \pi^0 p$ reaction from its threshold up to $W=2$~GeV have been used in order to perform a single-energy partial wave analysis with minimal model dependence. Continuity in energy was achieved by imposing constraints from fixed-$t$ analyticity in an iterative procedure. Reaction models were only used as starting point in the very first iteration. We demonstrate that with this procedure partial wave amplitudes can be obtained which show only a minimal dependence on the initial model assumptions.