2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/225114The exclusive production of ππand πρin hard γ^{\star}γscattering in the forward kinematical region where the virtual photon is highly off-shell are studied through the γ\toπ^- Transition Distribution Amplitudes. The calculation is based on a covariant Bethe-Salpeter approach, applied to the Nambu - Jona-Lasinio model, for the determination of the pion bound state. In particular it is shown that the pion pole contribution produces a large enhancement of the differential cross section for the pion pair production with respect to previous estimates.To appear in the proceedings of Light Cone 2008: Relativistic Nuclear and Particle Physics (LC2008), Mulhouse, France, 7-11 Jul 2008High Energy Physics - Phenomenologytext