Speaker
Description
The matching of NLO predictions to parton showers has long been considered a solved problem. However, it has recently attracted renewed attention with the development of a new generation of parton showers capable of achieving next-to-leading logarithmic (NLL) or even higher logarithmic accuracy. This progress poses new challenges for existing matching schemes and makes it worthwhile to revisit established approaches and explore new solutions.
In this work, we present a resonance-aware strategy for matching full off-shell NLO QCD predictions at lepton colliders to the PYTHIA 8 Simple Shower. As a case study, we focus on processes involving top–antitop pair production. Fixed-order predictions are obtained using the MC@NLO method combined with Catani-Seymour subtraction. Distortions of resonance line shapes are avoided by providing the full resonance cascade information on an event-by-event basis to the parton shower and by adapting the matching procedure through the introduction of dedicated counterterms.