Abstract
We present a scheme for the generation of central exclusive final states in the PYTHIA8 program. The implementation allows for the investigation of higher-order corrections to such exclusive processes as approximated by the initial-state parton shower in PYTHIA8.
To achieve this, the spin and colour decomposition of the initial-state shower has been worked out, in order to determine the probability that a partonic state generated from an inclusive sub-process followed by a series of initial-state parton splittings can be considered as an approximation of an exclusive colour- and spin-singlet process. We use our implementation to investigate the effects of parton showers on some examples of central exclusive processes, and we find sizeable effects on di-jet production, while the effects on e.g. central exclusive Higgs production are minor.