Parton densities and dipole cross-sections at small x in large nuclei

Abstract.

Unintegrated gluon densities in nuclei, dipole-nucleus cross-sections and quark densities are numerically investigated in the high-color limit, with the scattering on a heavy nucleus exactly described by the sum of fan diagrams of BFKL pomerons. The initial condition for the evolution in rapidity is quickly forgotten, and the gluon density presents a “supersaturation” pattern, as previous studies indicated. Both dipole-nucleus cross-sections and quark densities present the expected saturation features. Identifying the position in transverse momentum l of the maximum of the gluon distribution with the saturation momentum $Q_{\mathrm{s}}(y,b)$, at large rapidities all distributions depend on only one variable, $l/Q_{\mathrm{s}}(y,b)$ or $rQ_{\mathrm{s}}(y,b)$.