Resonance-Aware NLO+PS Matching for Off-Shell Top–Antitop Production at Lepton Colliders

by Daniele Lombardi (Università di Torino)

Thursday 19 Mar 2026, 14:00 → 15:00 Europe/Zurich

U2 - 5017 (Universita` Milano Bicocca)

• The matching of NLO predictions to parton showers has traditionally been considered a solved problem. However, recent advancements in parton shower development, capable of achieving next-to-leading logarithmic (NLL) or even higher logarithmic accuracy, have renewed interest in this area. These developments present new challenges for existing matching schemes, prompting a reassessment of established approaches and the exploration of new solutions.

  In this seminar, I will discuss a resonance-aware strategy for matching full off-shell NLO QCD predictions at lepton colliders to the PYTHIA 8 Simple Shower. The fixed-order results are obtained using the Monte Carlo integrator MoCaNLO, which I will briefly introduce. As a case study, I will focus on top-antitop pair production processes. The NLO matching is pursued using the MC@NLO method in combination 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.