Pair production of χc states at collider energies

In perturbative QCD used together with the nonrelativistic bound-state formalism, the production of χc pairs in pp, ep, and γγ collisions is considered at energies of present and future colliders. A variety of partonic subprocesses, including those governed by the color-singlet and color-octet mechanisms, are taken into account. Regions in the phase space where each of the partonic subprocesses contributes most significantly are found from analysis of energy and angular distributions. The role of beam polarization is also discussed