Determining the CP parity of Higgs bosons at the LHC in the $\tau$ to 1-prong decay channels

TL;DR

This paper introduces a method to determine the CP properties of Higgs bosons at the LHC using tau decay channels, capable of distinguishing scalar, pseudoscalar, and CP-violating states with robustness against measurement uncertainties.

Contribution

The paper presents a novel observable-based approach for CP determination of Higgs bosons in tau decay channels, applicable at the LHC and future colliders.

Findings

Method effectively discriminates scalar and pseudoscalar Higgs states.

Maintains discriminating power despite measurement uncertainties.

Applicable to various tau decay modes, including at future linear colliders.

Abstract

We propose a method for determining the CP nature of a neutral Higgs boson or spin-zero resonance $\phi$ at the CERN Large Hadron Collider (LHC) in its $\phi\to\tau^{-}\tau^{+}$ decay channel. The method can be applied to any 1-prong $\tau$-decay mode, which comprise the majority of the $\tau$-lepton decays. The proposed observables allow to discriminate between pure scalar and pseudoscalar Higgs-boson states and/or between a CP-conserving and CP-violating Higgs sector. We show for the decays $\tau\to\pi\nu_{\tau}$ that the method maintains its discriminating power when measurement uncertainties are taken into account. The method will be applicable also at a future linear $e^{+}e^{-}$ collider.