Indirect CP probes of the Higgs--top-quark interaction at the LHC

TL;DR

This paper assesses current and future constraints on the Higgs boson's CP properties, focusing on its interaction with top quarks, using collider data and proposing a novel analysis strategy at the HL-LHC.

Contribution

It provides a comprehensive evaluation of existing constraints on Higgs CP properties and introduces a new method to measure tH production without assuming Higgs CP nature.

Findings

Current constraints limit Higgs CP mixing with top quarks

Future measurements can improve sensitivity to Higgs CP properties

Proposed analysis strategy enables model-independent tH measurement at HL-LHC

Abstract

The precise determination of the Higgs boson CP properties is among the most important goals for existing and future colliders. In this work, we evaluate existing constraints on the CP nature of the Higgs interaction with top quarks taking into account all relevant inclusive and differential Higgs boson measurements. We study the model dependence of these constraints by allowing for deviations from the SM predictions also in the Higgs couplings to massive vector boson, photons, and gluons. Additionally, we evaluate the future prospects for constraining the CP nature of the top-Yukawa coupling by total rate measurements. In this context, we propose an analysis strategy for measuring tH production at the HL-LHC without relying on assumptions about the Higgs CP character.