Central exclusive chi_c meson production at the Tevatron revisited

TL;DR

This paper revisits the production of chi_c mesons at the Tevatron, showing that chi_c1 and chi_c2 rates are comparable to chi_c0, and introduces a new Monte Carlo generator to model and analyze these processes.

Contribution

It extends the formalism to include chi_c1 and chi_c2 mesons and develops SuperCHIC, a Monte Carlo generator for their exclusive production, suggesting possible earlier observations.

Findings

Chi_c1 and chi_c2 production rates are comparable to chi_c0.

Current experimental cuts may not distinguish between the three states.

Exclusive chi_c1 and chi_c2 production might have already been observed.

Abstract

Motivated by the recent experimental observation of exclusive chi_c events at the Tevatron, we revisit earlier studies of central exclusive scalar chi_c0 meson production, before generalising the existing formalism to include chi_c1 and chi_c2 mesons. Although chi_c0 production was previously assumed to be dominant, we find that the chi_c1 and chi_c2 rates for the experimentally considered chi_c -> J/psi gamma -> mu+ mu- gamma decay process are in fact comparable to the chi_c0 rate. We have developed a new Monte Carlo event generator, SuperCHIC, which models the central exclusive production of the three chi_c states via this decay chain, and have explored possible ways of distinguishing them, given that their mass differences are not resolvable within the current experimental set-up. Although we find that the severity of current experimental cuts appears to preclude this, the acceptance does not change crucially between the three states and so our conclusions regarding the overall rates remain unchanged. This therefore raises the interesting possibility that exclusive chi_c1 and chi_c2 production has already been observed at the Tevatron.