Parton showers and matching uncertainties in top quark pair production with Herwig 7 Kyle Cormier, Simon Plätzer, Christian Reuschle, Peter Richardson and Stephen Webster Eur. Phys. J. C, 79 11 (2019) 915 Published online: 12 November 2019 DOI: 10.1140/epjc/s10052-019-7370-7