Photon-Photon Interaction in Glueball Production

In the last years many exotic states have been identified in several colliders around the world. One of the exotic states provided in QCD is the glueball. Using a non-relativistic gluon bound-state model, we compute Gamma(G -> gamma gamma),where G is a pseudoscalar, tensor, or scalar digluon. For the starting from the amplitudes we considers the process gamma gamma -> g* g* at threshold, where the amplitudes are obtained in perturbative QCD at lowest order by deriving them from QED calculation and the g's are massive constituent gluons. In this calculation the unknown parameters of the model, such as the digluon wave function, are obtained using measured values of Gamma(J/psi -> G gamma). Our theorical results are compared with the present experimental limits for the various glueballs candidates.