Within the pion-nucleon chiral perturbation theory we derive the leading chiral correction to the nucleon GPD at ξ = 0. We discuss the difficulties of consideration of nonlocal light-cone operators within the theory with a heavy particle and the methods to solve the difficulties. The consideration of the chiral corrections directly for nonlocal operators allows to resolve the ambiguity of the inverse Mellin transformation. In particular, we show that the mixing between axial and vector GPDs are of order m 2 π /M 2 N , which is two orders of magnitude less that it follows from the Mellin moments calculation. *

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Based on the chiral perturbation theory, we investigate the low-energy dynamics of nucleon parton distributions. We show that in different regions of the momentum fraction x the chiral expansion is significantly different. For nucleon parton distributions these regions are characterized by x ∼ 1, x ∼ m π /M N and x ∼ (m π /M N ) 2 . We derive extended counting rules for each region and obtain model-independent results for the nucleon parton distributions down to x m 2 π /M 2 N ≈ 10 −2 .