The QCD pomeron in ultraperipheral heavy ion collisions : I. The double J/Ψ production

Abstract

The contribution of the QCD pomeron to the process AA → AAJ/Ψ J/Ψ is discussed. We focus on the photon–photon collision, with the quasi-real photon coming from theWeizs¨acker–Williams spectrum of the nuclei. We calculate the cross section for this process considering the solution of the LLA BFKL equation at zero momentum transfer using a small t approximation for the differential cross section of the subprocess. Furthermore, the impact of non-leading corrections to the BFKL equation is also analyzed. In both cases the cross section is found to increase with the energy, predicting considerable values for the LHC energies. Moreover, we compare our results with the Born two-gluon approximation, which is energy independent at the photon level. Our results indicate that the experimental analyses of this process can be useful to discriminate the QCD dynamics at high energies.