STRUCTURE FUNCTIONS AND PARTON MOMENTA DISTRIBUTION IN THE HADRON REST SYSTEM

The alternative to the standard formulation of the quark-parton model (QPM) in the infinite momentum frame is suggested. The proposed approa ch does not require any extra assumptions in addition, consistently ta kes into account the parton transversal momenta, and does not prefer a ny special reference system, The standard approach is involved as a li miting case. As a result, the modified relations between the structure and distribution functions are obtained together with some constraint on their shape. The comparison with experimental data offers speculat ion about the values of the effective masses of quarks, which emerge a s a free parameter in the approach.