Higgs CP properties using the tau decay modes at the ILC

TL;DR

This study assesses the potential of a future linear collider to determine the CP properties of the Higgs boson via tau decay modes, estimating a precision of 2.8 degrees in the scalar-pseudoscalar mixing angle.

Contribution

It introduces a method to measure the Higgs CP nature at a linear collider using tau decay angular distributions, with detailed simulation-based precision estimates.

Findings

Estimated CP mixing angle precision of 2.8 degrees at 250 GeV

Demonstrated the feasibility of CP property measurement using tau decay modes

Provided background and measurement uncertainty assessments

Abstract

We investigate the prospects of determining the CP nature of the 126 GeV neutral spin-0 (Higgs) boson h, discovered at the LHC, at a future linear collider. We consider the production of h by the Higgsstrahlung process and its subsequent decays to tau leptons. We investigate how precisely a possible pseudoscalar component of h can be detected by the measurement of a suitably defined angular distribution, if all major decay modes of the tau lepton are used. From our numerical simulations, we estimate the expected precision to the scalar-pseudoscalar mixing angle, including estimates of the background and of measurement uncertainties, to be 2.8 degree for Higgs-boson production at a center-of-mass energy of 250 GeV and for a collider with integrated luminosity of 1 inverse attobarn.