Dr. Stefano Di Noi

Four-top operators: technical subleties and current bounds 

Abstract

In this talk I will introduce the SMEFT four-top operators, effective parametrizations of BSM interactions involving the third generation of quarks. Their chiral nature makes the computation of loop contributions to a broad class of observables highly non-trivial, following from the delicate treatment of the fifth gamma matrix in dimensional regularization. I will showcase these aspects in single-Higgs production, discussing how different computational schemes can lead to different result and how to interpret such differences. 
Finally, I will present the state-of-the-art bounds on four-top operators, resulting from a combination of top-quark, Higgs, and electroweak precision data.