Central exclusive meson pair production in the perturbative regime at hadron colliders

TL;DR

This paper calculates the perturbative QCD amplitudes for central exclusive meson pair production at hadron colliders, providing numerical predictions and discussing non-perturbative effects.

Contribution

It explicitly computes gg --> MMbar helicity amplitudes using MHV techniques, advancing the understanding of meson pair production in the perturbative regime.

Findings

Calculated helicity amplitudes for various meson states

Provided numerical predictions for different final states

Discussed the role of non-perturbative contributions at low transverse momentum

Abstract

The central exclusive production (CEP) of heavy resonance states that subsequently decay into meson pairs, MMbar, is an important signature for such processes at hadron colliders. However there is a potentially important background from the direct QCD production of meson pairs, as mediated for example by the exclusive gg --> MMbar hard scattering subprocess. This is in fact an interesting process in its own right, testing novel aspects of perturbative QCD technology. We explicitly calculate the gg --> MMbar helicity amplitudes for different meson states within the hard exclusive formalism, and comment on the application of MHV techniques to the calculation. Using these results, we describe how meson pair CEP can be calculated in the perturbative regime, and present some sample numerical predictions for a variety of final states. We also briefly consider the dominant non-perturbative contributions, which are expected to be important when the meson transverse momentum is small.