Pair production of heavy quarkonium and B{sub c}{sup ()} 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 p{sub t} distribution of double J/{psi} production in the CSM is dominant over that in the COM when p{sub t} is smaller than about 10 GeV. For the production of double {upsilon}, 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 p{sub t} distributions in the large p{sub t} region are useful in clarifying the effects of COM on the quarkonium production. We also investigate the pair production of S-wave B{sub c} and B{sub c}* mesons, and the measurement of these processes is useful to test the CSM and extract the long-distance matrix elements for the B{sub c} and B{sub c}* mesons. Aside from numerical calculations, analytical expressions for the production differential cross sections of all these processes are also given.