Color dipole cross-section from unifying the color dipole picture and improved saturation models

We present an analysis of the color-dipole picture (CDP) for determination of the gluon density at low-x which is obtained from the Altarelli-Martinelli equation by expansion at distinct points of expansion. The dipole cross-sections with respect to the improved saturation model of Bartels-Golec-Biernat-Kowalski (BGK) are obtained in a wide range of transverse sizes r and compared with the Golec-Biernat-Wüsthoff (GBW) model. We find that the model gives a good description of the dipole cross-section at large r which confirms saturation and matches the perturbative QCD result at a small r due to the significant role of the running of the gluon distribution. The transition between these regions occurs with decreasing transverse sizes with a decrease of Bjorken x and dependence on the expansion point.