Towards Hadronisation on GPUs

Complete event generation on hardware accelerators such as GPUs requires vectorising the algorithms of components such as parton showers and hadronisation. To this end, I implemented a simplified cluster hadronisation and hadronic decay model in the GPU parton shower program GAPS, with one thread per event and each stage of the algorithm as a separate kernel. I compared simulation results for $e^{+}{e}^{-}\to \text{hadrons}$ at the $Z$ pole with the Herwig event generator and with ALEPH and L3 data, and measured execution times on an NVIDIA V100 GPU. The results agree well with Herwig, and GAPS generates one million hadron-level events (NLO hard process, shower, hadronisation and decays) in about four seconds on this GPU.