The double diffractive photoproduction of J/\psi mesons, \gamma p \rightarrow J/\psi Y, has been studied in ep collisions with the ZEUS and H1 detectors at HERA. The differential cross section d\sigma /dt, where t is the four-momentum transfer squared at the proton vertex, has been measured for |t|< 30 {GeV²}. The total cross section has been presented as a function of the photon-proton centre-of-mass energy, W_{\gamma p}, in the kinematic range 50_{\gamma p}<245 GeV. The results are compared with perturbative QCD models based on BFKL and DGLAP evolution.

PACS numbers: 13.20.Gd