Nonperturbative and spin effects in the central exclusive production of the tensor χc(2+) meson

We discuss central exclusive production (CEP) of the tensor χc(2+) meson in proton-(anti)proton collisions at Tevatron, RHIC, and LHC energies. The amplitude for the process is derived within the kt-factorization approach. Differential and total cross sections are calculated for several unintegrated gluon distribution functions (UGDFs). We compare exclusive production of all charmonium states χc(0+), χc(1+) and χc(2+). Good description of the recent Tevatron data is achieved both with Martin-Ryskin phenomenological UGDF and UGDF based on unified BFKL-DGLAP approach. Unlike for Higgs production, the main contribution to the diffractive amplitude of heavy quarkonia comes from nonperturbative region of gluon transverse momenta Qperpendicular<1 GeV. At y≅0, depending on UGDF we predict the contribution of χc(1+,2+) to the J/Ψ+γ channel to be comparable or larger than that of the χc(0+) one. This is partially due to a significant contribution from lower polarization states λ=0 for χc(1+) and λ=0, ±1 for χc(2+) meson. Corresponding theoretical uncertainties are discussed.