A New Observable for Measuring CP Property of Top-Higgs Interaction

TL;DR

This paper introduces a new dihedral angle observable to determine the CP nature of the top-Higgs interaction in $t\bar{t}H$ production at the LHC, capable of distinguishing CP properties with high confidence.

Contribution

It proposes a novel dihedral angle observable for measuring the CP property of top-Higgs interactions in $t\bar{t}H$ production at the LHC.

Findings

The dihedral angle distribution can distinguish CP-even and CP-odd hypotheses.

The method achieves 95% confidence level discrimination with about 180 fb$^{-1}$ of data.

Applicable to Higgs decay modes $H\to b\bar{b}$ and $H\to \gamma\gamma$.

Abstract

We propose a new dihedral angle observable to measure the CP property of the interaction of top quark and Higgs boson in the $t\bar{t}H$ production at the 14~TeV LHC. We consider two decay modes of the Higgs boson, $H\to b\bar{b}$ and $H\to \gamma\gamma$ and show that the dihedral angle distribution is able to distinguish the CP-even and the CP-odd hypothesis at 95\% confidence level with an integrated luminosity of $\sim 180~{\rm fb}^{-1}$.