On the description of exclusive processes beyond the leading twist approximation

We describe hard exclusive processes beyond the leading twist approximation in a framework based on the Taylor expansion of the amplitude around the dominant light-cone directions. This naturally introduces an appropriate set of non-perturbative correlators whose number is minimalized after taking into account QCD equations of motion and the invariance under rotation on the light-cone. We examplify this method at the twist 3 level and show that the coordinate and momentum space descriptions are fully equivalent.
Comment: 6 pages, 2 figures, modified and slightly expanded version to be published in Phys.Lett. B