Unitary constraints on charged pion photoproduction at large p⊥
Around $$\theta_{\pi}=$$90$$^\circ$$, the coupling to the $$\rho^\circ N$$ channel leads to a good accounting of the charged pion exclusive photoproduction cross section in the energy range 3 < Eγ < 10 GeV, where experimental data exist. Starting from a Regge Pole approach that successfully describes vector meson production, the singular part of the corresponding box diagrams (where the intermediate vector meson-baryon pair propagates on-shell) is evaluated without any further assumptions (unitarity). Such a treatment provides an explanation of the $$s^{-7}$$ scaling of the cross section. Furthermore, elastic rescattering of the charged pion improves the basic Regge pole model at forwardmore »