Combination of measurements of CP properties of Higgs boson interactions with vector bosons using proton-proton collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

TL;DR

This paper combines multiple measurements from the ATLAS experiment to constrain the CP properties of Higgs boson interactions with vector bosons, setting the most stringent limits to date on certain SMEFT Wilson coefficients without assuming specific models.

Contribution

It provides the first simultaneous constraints on three SMEFT coefficients related to CP violation in Higgs interactions using a comprehensive data set.

Findings

No evidence of CP violation was observed.

Over 40% improvement in limits on specific SMEFT coefficients.

First constraints on three Wilson coefficients simultaneously.

Abstract

A combination of measurements of the CP properties of Higgs boson interactions with electroweak gauge bosons is presented, using 140 fb$^{-1}$ of proton-proton collisions at $\sqrt{s} = 13$ TeV recorded by the ATLAS detector. Results from $H\to\tau\tau$, $H\to WW^{*}$, $H\to\gamma\gamma$, $H\to ZZ^{*}$, and $WH,H\to b\bar{b}$ channels are combined. No evidence of CP violation is observed, and constrains on the CP-violating operators in the SMEFT framework are set in the Warsaw basis. The results from the combination improve by over 40% on previous individual limits on $c_{H\tilde{W}}$ and, for the first time, simultaneous constraints on three coefficients $c_{H\tilde{W}}$, $c_{H\tilde{B}}$, and $c_{H\tilde{W}B}$ are set. This limits are the most stringent constraints to date on the relevant Wilson coefficients in the SMEFT framework with minimum model dependence.