Top polarization as a probe of CP-mixing top-Higgs coupling in tjh signals

In this paper, we explore beyond the Standard Model top-Higgs Yukawa couplings as a function of a CP-mixing parameter xi(t) at the 14 TeV HL-LHC in the process pp -> thj. We observe that angular variables of the decay products of the top are nontrivially sensitive to xi(t) . This fact is exploited in a full detector level analysis that employs machine learning techniques to optimize signal sensitivity on a suite of variables, including lepton azimuthal angle. The key result of this study is an improved projected exclusion limit on xi(t )even when including the realistic effects of detector smearing and a conservative estimate of systematic error.