Deeply-virtual and Photoproduction of Mesons at Higher-order and Higher-twist

Abstract

Both deeply-virtual and photoproduction of mesons offer promising access to generalized parton distributions and complementary description of different kinematical regions. The higher-order contributions offer stabilizing effect with respect to the dependence on renormalization scales, while higher-twist effects have been identified as especially important in the case of the production of pseudo-scalar mesons. This was confirmed by recent evaluation of the complete twist-3 contribution to $\pi$ and $\eta$/$\eta'$ photoproduction and its confrontation with experimental data.