DIFFRACTIVE J PSI PRODUCTION IN HIGH-ENERGY GAMMA-GAMMA COLLISIONS ASA PROBE OF THE QCD POMERON/

The reaction gamma gamma-->J/Psi J/Psi is discussed assuming dominance of the QCD BFKL pomeron exchange. We give prediction far the cross-se ction of this process for LEP2 and TESLA energies. We solve the BFKL e quation in the non-forward configuration taking into account dominant non-leading effects which come from the requirement that the virtualit y of the exchanged gluons along the gluon ladder is controlled by thei r transverse momentum squared. We compare our results with those corre sponding to the simple two gluon exchange mechanism and with the BFKL pomeron exchange in the leading logarithmic approximation. The BFKL ef fects are found to generate a steeper t-dependence than the two gluon exchange. The cross-section is found to increase with increasing CM en ergy W as (W-2)(2 lambda). The parameter lambda is slowly varying with W and takes the values lambda similar to 0.23-0.28. The magnitude of the total cross-section for the process gamma gamma --> J/Psi J/Psi is found to increase from 4 to 26 ph within the energy range accessible at LEP2. The magnitude of the total cross-section for the process e(+) e(-) --> e(+)e(-) J/Psi J/Psi with antitagged e(+) and e(-) is estimat ed to be around 0.1 pb at LEP2. (C) 1998 Published by Elsevier Science B.V. All rights reserved.