Using the approximate conformal invariance of QCD at high energies we consider a simple anti- de Sitter black disk model to describe saturation in deep inelastic scattering. Deep inside saturation the structure functions have the same power law scaling, F(T) similar to F(L) similar to x(-w), where w is related to the expansion rate of the black disk with energy. Furthermore, the ratio F(L)/F(T) is given by the universal value 1+3/3+w, independently of the target. For gamma* - gamma* scattering at high energies we obtain explicit expressions and ratios for the total cross sections of transverse and longitudinal photons in terms of the single parameter omega.
Marcos Rubinstein, Antonio Sunjerga, Amirhossein Mostajabi
Robert Dalang, Carsten Hao Ye Chong