Latest news in MATRIX: Advanced perturbative predictions for ttH and off-shell ttbar production

by Dr Chiara Savoini (TUM)

Monday 12 Jan 2026, 15:00 → 16:00 Europe/Berlin

SR2

The production of top quarks at high-energy colliders provides a powerful probe of the Standard Model (SM) and a sensitive window to new physics. In hadronic collisions, the dominant source of top quarks is top-antitop pair (ttbar) production, which represents a sizable and challenging background for several physics studies. Due to the top quark's short lifetime, the observed signature is almost exclusively characterised by two bottom quarks and the decay products of the two W bosons. Yet the same final state can arise from single-top production in the tW channel, non-resonant topologies, and from their quantum interferences, thus requiring a unified theoretical description. In addition to ttbar production, top quarks produced in association with a massive boson offer a highly sensitive way of testing the SM. Despite their smaller cross sections, these processes are now being measured with increasing precision, which calls for correspondingly accurate theoretical predictions.

In this seminar, I will present recent progress within the MATRIX framework aimed at delivering advanced perturbative predictions for two key processes: on-shell ttH production, which provides direct access to the top-quark Yukawa coupling, and off-shell ttbar production in the dilepton channel (bb4l).
I will briefly review the qT-subtraction formalism, particularly its extension to heavy-quark processes, which enables the handling and cancellation of infrared singularities. I will then discuss the construction of physically motivated approximations for the missing two-loop contributions, highlight the key theoretical developments, and outline the challenges that remain on the path to full NNLO accuracy.
Finally, I will present differential results for ttH production, as well as updated bb4l predictions for the total cross section. The latter constitute the first foundational steps toward a complete NNLO QCD description of this multi-scale, multi-parton process.