Exploring the origin of small−x saturation in the collinear approach

A modification of the collinear evolution equations as an appropriate approach to improving the behavior of parton distribution functions in the region of small longitudinal momentum fractions and to finding more theoretical arguments to clarify the possible appearance of the saturation regime is suggested. It is argued that parton diffusion in the rapidity space at large parton densities along the space-time evolution could result in the emergence of a natural saturation scale on which freezing actually occurs.