The QCD pomeron in e+e- collisions

Abstract

The contribution of the QCD pomeron to the processes: e+e- to e+e- J/psi J/psi and e+ e- to e+ e- hadrons (with tagged electrons) is discussed. We focus on reactions which occur via photon-photon collisions, with virtual photons coming from the Weizsaecker-Wiliams spectrum of the electrons. We stress the importance of the non-leading corrections to the BFKL equation and take into account dominant non-leading effects which come from the requirement that the virtuality of the exchanged gluons along the gluon ladder is controlled by their transverse momentum squared. The \gamma* \gamma* cross-sections are found to increase with increasing \gamma* \gamma* CM energy W as (W^2)^{\lambda_P} while the cross-section for \gamma\gamma to J/psi J/psi is found to increase as (W^2)^{2\lambda_P}. The parameter \lambda_P is slowly varying with energy W and takes the values lambda_P \sim 0.23 - 0.35 depending on the process. We also analyze the contribution of the soft pomeron for the total \gamma* \gamma* cross-section. We compare results of our calculations to the recent data from LEP.