The 2012 discovery of the Higgs boson opened a new window for particle physics, particularly in studying the Yukawa coupling of the Higgs boson to the top quark (yt). The only way of simultaneously measuring the magnitude and sign of yt is through the associated production of a single top quark and a Higgs boson (tHq).
In this seminar, a search for the tHq production is presented in a final state with two light leptons and one tau decaying hadronically using data from LHC Run 2's ATLAS detector. This task is extremely challenging due to the small cross-section of the tHq process and the final-state channel's mere 3.5% to the total tHq production, necessitating the use of machine learning techniques for reconstructing the events and separating the signal from the background.
This research, aiming to identify any excess of signal events over SM predictions, could indicate new physics, particularly CP-violating yt coupling.