[en] off-forward pion structure function ; non-perturbative effects
[en] We extend our model for the pion, which we used previously to calculate its diagonal structure function, to the off-forward case. The imaginary part of the off-forward y*pi -->. gamma*pi scattering amplitude is evaluated in the chiral limit (m(pi) = 0) and related to the twist-two and twist-three generalised parton distributions H, H-3, (H) over tilde (3). Non-perturbative effects, linked to the size of the pion and still preserving gauge invariance, are included. Remarkable new relations between H, H3 and (H) over tilde (3) are obtained and discussed. (C) 2004 Published by Elsevier B.V.