Elastic double diffractive production of axial-vector χc(1++) mesons and the Landau-Yang theorem

We discuss exclusive elastic double diffractive axial-vector χc(1+) meson production in proton-antiproton collisions at the Tevatron. The amplitude for the process is derived within the kt-factorization approach with unintegrated gluon distribution functions (UGDFs). We show that the famous Landau-Yang theorem is not applicable in the case of off-shell gluons. Differential cross sections for different UGDFs are calculated. We compare exclusive production of χc(1+) and χc(0+). The contribution of χc(1+) to the J/Ψ+γ channel is smaller than that of the χc(0+) decay, but not negligible and can be measured. The numerical value of the ratio of the both contributions is much less dependent on the UGDFs modeling than the cross sections themselves.