Analysis of the CP structure of the Yukawa coupling between the Higgs boson and $\tau$ leptons in proton-proton collisions at $\sqrt{s} =$ 13 TeV

TL;DR

This paper presents the first measurement of the CP structure of the Higgs boson’s Yukawa coupling to tau leptons using LHC data, finding results consistent with the Standard Model and disfavoring a pure CP-odd scenario.

Contribution

It introduces a novel analysis method to measure the CP properties of the Higgs-tau Yukawa coupling using angular correlations in decay planes.

Findings

Effective mixing angle measured as -1 ± 19 degrees.

Data disfavors pure CP-odd scenario at 3.0 sigma.

Results align with Standard Model predictions.

Abstract

The first measurement of the CP structure of the Yukawa coupling between the Higgs boson and $\tau$ leptons is presented. The measurement is based on data collected in proton-proton collisions at $\sqrt{s} =$ 13 TeV by the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb$^{-1}$. The analysis uses the angular correlation between the decay planes of $\tau$ leptons produced in Higgs boson decays. The effective mixing angle between CP-even and CP-odd $\tau$ Yukawa couplings is found to be $-$1 $\pm$ 19$^\circ$, compared to an expected value of 0 $\pm$ 21$^\circ$ at the 68.3% confidence level. The data disfavour the pure CP-odd scenario at 3.0 standard deviations. The results are compatible with predictions for the standard model Higgs boson.