2013/08/31 by Jean-Philippe Lansberg, Hua-Sheng Shao · 1 citation
Physics and Astronomy · #hep-ph #hep-ex
paper · pdf · doi:10.1103/physrevlett.111.122001
published as Phys. Rev. Lett. 111 (2013) 122001 · 5 pages, 11 figures, LaTeX. v2: matches the PRL version (3 typos corrected and title changed)
arxiv created 2013/09/26 · arxiv updated 2013/09/30
We proceed for the first time to the evaluation of the Born cross section for J/psi+eta(c) production, namely via g+g -> J/psi+eta(c)+g, and show that it has a harder PT spectrum than the J/psi-pair yield at Born level. If one stuck to a comparison at Born level, one would conclude that J/psi+eta(c) production would surpass that of J/psi+J/psi at large PT. This is nonetheless not the case since J/psi-pair production, as for single J/psi, receives leading-PT contributions at higher orders in alphas. We also present the first evaluation of these leading-PT next-to-leading order contributions. These are indeed significant for increasing PT and are of essential relevance for comparison with forthcoming data. We also compute kinematic correlations relevant for double-parton-scattering studies. Finally, we evaluate the polarisation of a J/psi accompanied either by a eta(c) or a J/psi and another light parton. These results may be of great help to understand the polarisation of quarkonia produced at high energies.