Boosting the Direct CP Measurement of the Higgs-Top Coupling

TL;DR

This paper proposes a new method to measure the CP-structure of the top-Higgs coupling at the LHC by analyzing the azimuthal angle difference between leptons in boosted Higgs events, enhancing measurement sensitivity.

Contribution

It introduces a novel variable based on lepton azimuthal angle difference and demonstrates its effectiveness in probing the CP nature of the top-Higgs coupling using boosted Higgs techniques.

Findings

Enhanced sensitivity to CP-structure in boosted Higgs regime

Effective use of jet-substructure tagging for Higgs identification

Feasibility of measuring top-Higgs coupling at 13 TeV LHC

Abstract

Characterizing the 125 GeV Higgs is a critical component of the physics program at the LHC Run II. In this Letter, we consider $t\bar{t}H$ associated production in the dileptonic mode. We demonstrate that the difference in azimuthal angle between the leptons from top decays can directly reveal the CP-structure of the top-Higgs coupling with the sensitivity of the measurement substantiality enhanced in the boosted Higgs regime. We first show how to access this channel via $H \to b\bar{b}$ jet-substructure tagging, then demonstrate the ability of the new variable to measure CP. Our analysis includes all signal and background samples simulated via the MC@NLO algorithm including hadronization and underlying-event effects. Using boosted Higgs substructure with dileptonic tops, we find that the top-Higgs coupling strength and the CP structure can be directly probed with achievable luminosity at the 13 TeV LHC.