In depth analysis of the combined HERA data in the dipole models with and without saturation

Abstract

We present an updated impact parameter dependent saturation model determined through a fit to the combined HERA I and I+II reduced cross section data. The same HERA data are used to fit the linearized version of the applied dipole amplitude, which makes it possible to estimate the magnitude of the saturation effects in various experiments. We find that both parametrizations provide comparable descriptions of the considered data when an effective confinement scale dynamics is incorporated with quark masses. Moreover, it is possible to consistently determine the light and charm quark masses. The role of potentially nonperturbatively large dipoles is examined in detail, with the result that, especially in the case of the structure function F2, their contribution is numerically significant. The potential to discriminate between the two models in future e+p and e+A experiments is also illustrated.