The QCD pomeron in ultraperipheral heavy ion collisions: I. The double productionV.P. Gonçalves1 and M.V.T. Machado2
1 Instituto de Física e Matemática, Universidade Federal de Pelotas, Caixa Postal 354, CEP 96010-090, Pelotas, RS, Brazil
2 High Energy Physics Phenomenology Group, IF-UFRGS, Caixa Postal 15051, CEP 91501-970, Porto Alegre, RS, Brazil
(Received: 12 December 2002 / Published online: 7 March 2003 )
The contribution of the QCD pomeron to the process is discussed. We focus on the photon-photon collision, with the quasi-real photon coming from the Weizsäcker-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.
© Società Italiana di Fisica, Springer-Verlag 2003