Erlangen 2026 – scientific programme

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T: Fachverband Teilchenphysik

T 67: Top Physics III

T 67.4: Talk

Thursday, March 19, 2026, 17:00–17:15, KH 00.011

Unfolding tops - using ATLAS to create detector-independent data — •Elia Schmidt, Richard Nisius, Changqiao Li, Xuewei Jia, and Dimbiniaina Rafanoharana — Max Planck Institute for Physics

The top-quark mass is an important fundamental parameter of the standard model. While its exact value has profound implications for Particle Physics, e.g. the stability of the QCD vacuum, its determination is hampered by theoretical ambiguities. The most precise measurements, performed by the big LHC Collaborations, are systematically limited and suffer from substantial modelling uncertainties.

In this presentation I will give a short overview of the theoretical issues associated with top-quark mass measurements and motivate the concept of data unfolding. The ongoing ATLAS analysis I am involved in has the goal of publishing an unfolded invariant mass distribution of lepton-jet pairs from tt decays. I use it as an example to show how data from ATLAS are processed to create a distribution which is essentially independent of detector-related uncertainties. The unfolded distribution can then be compared to all theoretical predictions, allowing conceptually sound top-quark mass determinations within a chosen model.

Keywords: ATLAS; Top Quark Mass; Unfolding