Pair production of heavy quarkonium and Bc(*) mesons at hadron colliders

We investigate the pair production of S-wave heavy quarkonium at the LHC in the color-singlet mechanism (CSM) and estimate the contribution from the gluon fragmentation process in the color-octet mechanism (COM) for comparison. With the matrix elements extracted previously in the leading-order calculations, the numerical results show that the production rates are quite large for the pair production processes at the LHC. The pt distribution of double J/ψ production in the CSM is dominant over that in the COM when pt is smaller than about 10GeV. For the production of double Υ, the contribution of the COM is always larger than that in the CSM. The large differences in the theoretical predictions between the CSM and COM for the pt distributions in the large pt region are useful in clarifying the effects of COM on the quarkonium production. We also investigate the pair production of S-wave Bc and Bc* mesons, and the measurement of these processes is useful to test the CSM and extract the long-distance matrix elements for the Bc and Bc* mesons. Aside from numerical calculations, analytical expressions for the production differential cross sections of all these processes are also given.