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Physics and Astronomy Colloquium — Spring 2022 — Emanuele Usai
March 23, 2022 @ 3:30 pm - 5:00 pm
Speaker: – Emanuele Usai (Brown University)
Title: Rare Top Quark Processes at the New Physics Frontier
Abstract: The top quark was discovered in 1995 and plays a pivotal role in particle physics at the energy frontier at the LHC era.
The simultaneous production of four top quarks is an example of a rare process in the Standard Model (SM) and one of the promising channels to search for signals of new physics beyond the standard model. The production of four top quarks is interesting in its own right since experimental data is expected to challenge state-of-the-art perturbative QCD calculation techniques. The final state provides direct ways to constrain otherwise tricky to measure SM parameters such as the top quark Yukawa coupling and a handful of SM Effective Field Theory parameters sensitive to the quartic couplings between top quarks. These measurements would provide crucial input to the understanding of the SM as they are model-independent and typically not very sensitive to the SM hypothesis.
If the scale of new physics is too high to be observed directly, it can manifest itself as a deviation from the SM, e.g., a modification of the four top quark cross section created by virtual and direct contributions of undiscovered particles beyond the SM.
In this seminar I will review the current experimental status of the study of four top quark production and discuss opportunities for measurements, new physics searches and other further analyses for the upcoming LHC Run and beyond. I will also discuss the advanced analysis techniques employed in these analyses.