Pair Production of Heavy Quarkonium and $B_c(^*)$ Mesons at Hadron Colliders

TL;DR

This paper compares the color-singlet and color-octet mechanisms for heavy quarkonium pair production at the LHC, providing predictions for different mesons and kinematic regions to clarify production mechanisms.

Contribution

It offers the first detailed comparison of CSM and COM contributions to heavy quarkonium pair production at the LHC, including $B_c$ mesons, aiding in understanding production mechanisms.

Findings

CSM dominates at low $p_t$ for double $J/eta$ production.

COM contribution is larger for double $$ production.

Differences in $p_t$ distributions help distinguish production mechanisms.

Abstract

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 $p_t$ distribution of double $J/\psi$ production in the CSM is dominant over that in the COM when $p_t$ is smaller than about 8GeV. 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 $p_t$ distributions in the large $p_t$ region are useful in clarifying the effects of COM on the quarkonium production. We also investigate the pair production of S-wave $B_c$ and $B_c^*$ mesons, and the measurement of these processes is useful to test the CSM and extract the LDMEs for the $B_c$ and $B_c^*$ mesons.