  We present a new approach for the calculation of the valence quark
distributions in the nucleon based on the scenario in which the spectrum of the
valence quarks at x>0.05 is generated through three main mechanisms:
interaction of valence quarks with the mean field generated by the residual
nucleon system, two and three quark short range interactions through gluon
exchanges. In the current report we present the first phase of the project in
which we develop a non-perturbative model for valence quark interaction in the
mean field of the nucleonic interior to describe their distribution in the
moderate x region (0.05 < x < 0.4). The short range quark-quark interaction
effects in our approach generate the high x tail of valence quark
distributions. The presented non-perturbative model is based on the picture in
which three relativistic valence quarks occupy the nucleon core at distances of
$\le 0.5$ Fm while interacting in the mean field generated by the residual
nucleon system. The calculations are based on the assumption of the a
factorization of the internal interaction of short-range three valence quarks
with the long-range interaction of these quarks with the residual system. The
theoretical approach is based on effective light-front diagrammatic approach
which allows us to introduce the valence quark and residual system wave
functions in a consistent way The parameters of these wave functions are fixed
by the position of the peak of the xf_q(x) distribution of valence quarks at
Q_0 corresponding to the charm-quark mass. With few parameters we achieved a
very reasonable description of the up and down valence quark distributions in
the moderate x region (x < 0.4), where one expects the mean field dynamics to
dominate. The model, however, systematically underestimates the high $x$ region
where enhanced contributions from partonic short-range correlations are
expected.
