Unitarity constraints on neutral pion electroproduction

At large virtuality Q2, the coupling to the vector meson production channels provides us with a natural explanation of the surprisingly large cross section of the neutral pion electroproduction recently measured at Jefferson Laboratory, without destroying the good agreement between the Regge pole model and the data at the real photon point. Elastic rescattering of the π0 provides us with a way to explain why the node, that appears at t∼−0.5 GeV2 at the real photon point, disappears as soon as Q2 differs from zero.