Chiral Expansion of Nucleon PDF at x similar to m(pi)/M-N

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 similar to 1, x similar to m(pi)/M-N and x similar to (m(pi)/M-N)(2). We derive extended counting rules for each region and obtain model-independent results for the nucleon parton distributions down to x greater than or similar to m(pi)(2)/M-N(2) approximate to 10(-2).