Finite sum of gluon ladders and high energy cross sections - art. no. 056010

A model for the Pomeron at t = 0 is suggested. It is based on the idea of a finite sum of ladder diagrams in QCD. Accordingly, the number of s-channel gluon rungs and correspondingly the powers of logarithms in the forward sc attering amplitude depends on the phase space (energy) available, i.e., as energy increases, progressively new prongs with additional gluon rungs in t he s-channel open. Explicit expressions for the total cross section involvi ng two and three rungs or, alternatively, three and four prongs [with In-2( s) and In-3(s) as highest terms, respectively] are fitted to the proton-pro ton and proton-antiproton total cross section data in the accelerator. regi on. Both QCD calculation and fits to the data indicate fast convergence of the series. In the fit, two terms (a constant and a logarithmically rising one) almost saturate the whole series, the In-2(s) term being small and the next one, In-3(s), negligible. Theoretical predictions for the photon-phot on total cross section are also given.