CMS pythia 8 colour reconnection tunes based on underlying-event data

Abstract

New sets of parameter tunes for two of the colour reconnection models, quantum chromodynamics-inspired and gluon-move, implemented in the pythia 8 event generator, are obtained based on the default CMS pythia 8 underlying-event tune, CP5. Measurements sensitive to the underlying event performed by the CMS experiment at centre-of-mass energies $\sqrt{s}=7$ and 13$\text{Te}\text{V}$, and by the CDF experiment at 1.96$\text{Te}\text{V}$ are used to constrain the parameters of colour reconnection models and multiple-parton interactions simultaneously. The new colour reconnection tunes are compared with various measurements at 1.96, 7, 8, and 13$\text{Te}\text{V}$ including measurements of the underlying-event, strange-particle multiplicities, jet substructure observables, jet shapes, and colour flow in top quark pair ($\text{t}\overline{\text{t}}$) events. The new tunes are also used to estimate the uncertainty related to colour reconnection modelling in the top quark mass measurement using the decay products of $\text{t}\overline{\text{t}}$ events in the semileptonic channel at 13$\text{Te}\text{V}$.