Contributions of gluon recombination to saturation phenomena

Parton distributions in the small x region are numerically predicted by using a modified Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equation with Glück-Reya-Vogt (GRV)-like input distributions. We find that gluon recombination at the twist-4 level obviously suppresses the rapid growth of parton densities with x decreasing. We show that before the saturation scale Qs2 is reached, saturation and partial saturation appear in the small x behavior of parton distributions in the nucleus and free proton, respectively. The antishadowing contributions to the saturation phenomena are also discussed.