We explore the direct Higgs-top CP measurement via the pp→ttˉh channel at the high-luminosity LHC. We show that a combination of machine learning techniques and efficient kinematic reconstruction methods can boost new physics sensitivity, effectively probing the complex ttˉh multi-particle phase space. Special attention is devoted to top quark polarization observables, uplifting the analysis from a raw rate to a polarization study. Through a combination of hadronic, semi-leptonic, and di-leptonic top pair final states in association with h→γγ, we obtain that the HL-LHC can probe the Higgs-top coupling modifier and CP-phase, respectively, up to ∣κt∣≲8% and ∣α∣≲13∘ at 68%~CL.
@article{arxiv.2110.07635,
title = {Machine learning the Higgs boson-top quark CP phase},
author = {Rahool Kumar Barman and Dorival Gonçalves and Felix Kling},
journal= {arXiv preprint arXiv:2110.07635},
year = {2022}
}