  We consider distributions of unpolarized (polarized) quarks in unpolarized
(polarized) hadrons. Our approach is based on QCD factorization. We begin with
study of Basic factorization for the parton-hadron scattering amplitudes in the
forward kinematics and suggest a model for non-perturbative contributions to
such amplitudes. This model is based on the simple observation: after emitting
an active quark by the initial hadron, the remaining set quarks and gluons
becomes unstable, so description of this colored state can approximately be
done in terms of resonances, which leads to expressions of the Breit-Wigner
type. for non-perturbative contributions to the distributions of unpolarized
and polarized quarks in the hadrons. Then we reduce these formulae to obtain
explicit expressions for the quark-hadron scattering amplitudes and quark
distributions in K_T- and Collinear factorizations.
