$t\bar{t}$ in PbPb [CMS, TH]

by Andre Govinda Stahl (CERN), Liliana Apolinario (LIP (PT))

Thursday 20 Nov 2025, 11:00 → 13:00 Europe/Zurich

4/2-011 - TH common room (CERN)

Abstract

Recent measurements by CMS and ATLAS have brought top quark pair production into the spotlight of heavy-ion physics, opening up exciting opportunities to probe the quark-gluon plasma (QGP). Beyond their role in constraining nuclear PDFs, top quarks offer a novel handle on the temporal evolution of QGP-induced modifications through their well-defined decay timescales. In particular, boosted top decays introduce delayed color charges that enable a time-differentiated analysis of jet quenching and color coherence phenomena. This session will begin with a theoretical overview of these ideas, followed by a presentation of the latest experimental progress from CMS, showcasing the most recent machine learning tools and calibration techniques that significantly enhance the precision of top measurements in heavy-ion environments. We will conclude with a look at upcoming developments, focusing on prospects for semi-leptonic channels.

Speakers

André Ståhl is an experimental physicist at CERN and a member of Compact Muon Solenoid collaboration, where he leads the Particle Flow reconstruction group and is involved in the Heavy Ion physics analysis group. He obtained his PhD in 2018 from the University Paris-Saclay while working in the Laboratory Leprince-Ringuet. His research centers on the study of QCD dynamics in heavy ion collisions at the LHC, focusing on hard probes of the Quark Gluon Plasma and nuclear medium.

 

Liliana Apolinário is a theoretical physicist at LIP, where she leads the Phenomenology group, and Invited Professor at Instituto Superior Técnico in Lisbon, Portugal. She obtained her PhD in 2013 from the University of Santiago de Compostela. Her research focuses on QCD and the quark–gluon plasma (QGP), with emphasis on jet quenching, jet substructure, and time-resolved probes of the QGP.