Is the Sullivan process compatible with QCD chiral dynamics?

We calculate the leading non-analytic quark-mass dependence in the moments of isovector quark distributions using heavy-baryon chiral perturbation the ory. The results differ from what has been obtained from the Sullivan proce ss in which hard scattering occurs through the virtual pion cloud of the nu cleon. Our results provide useful guidance in formulating meson-cloud model s consistent with chiral dynamics and can be used to constrain the extrapol ations of the existing lattice QCD results to the physical quark masses. (C ) 2001 Elsevier Science B.V. All rights reserved.