Double-diffractive χ meson production at the hadron colliders

The double-diffractive production of chi(c) and chi(b) mesons, with a rapidity gap on either side, is studied, using both the Regge formalism and the perturbative QCD approach. Due to the rather low scale, the exclusive double-diffractive process pp --> p + chi + p is predicted to dominate, whereas the probability that the incoming protons dissociate is expected to be relatively small. We evaluate the corresponding chi production cross sections at the Tevatron and LHC energies. For the double-diffractive process with proton dissociation, it is possible to select events with large transverse momenta transferred through the rapidity gaps, by measuring the transverse energy, E-perpendicular to, flows in the proton fragmentation regions. Then the large E-perpendicular to provides a scale to justify the use of perturbative QCD, and to allow a spin-parity analysis of the centrally produced system to be performed, by studying the azimuthal angular correlations between the directions of the forward and backward E-perpendicular to flows. The central production of the new X(3872) charmonium state is considered.