Constraining CP-violating Higgs Sectors at the LHC using gluon fusion

TL;DR

This paper explores how gluon fusion processes at the LHC can constrain the CP properties of the Higgs boson, especially distinguishing between CP-even and CP-odd components, using Higgs decay to tau pairs.

Contribution

It introduces a method focusing on gluon fusion production and Higgs decay to tau pairs to improve sensitivity to CP-violation in the Higgs sector at the LHC.

Findings

Can rule out pure CP-odd Higgs at 95% C.L. with 8 TeV data

Provides projected limits for 14 TeV LHC run

Highlights advantages of gluon fusion over vector boson coupling analyses

Abstract

We investigate the constraints that the LHC can set on a 126 GeV Higgs boson that is an admixture of CP eigenstates. Traditional analyses rely on Higgs couplings to massive vector bosons, which are suppressed for CP-odd couplings, so that these analyses have limited sensitivity. Instead we focus on Higgs production in gluon fusion, which occurs at the same order in the strong coupling for both CP-even and -odd couplings. We study the Higgs plus two jet final state followed by Higgs decay into a pair of tau leptons. We show that using the 8 TeV dataset it is possible to rule out the pure CP-odd hypothesis in this channel alone at nearly 95\% C.L, assuming that the Higgs is CP-even. We also provide projected limits for the 14 TeV LHC run.