Higgs CP Properties From Early LHC Data

TL;DR

This paper analyzes early LHC data to constrain the CP properties of the Higgs boson, finding that a pure CP-odd Higgs is disfavored and that mixing angles are limited, with potential for tighter constraints in future runs.

Contribution

It introduces a general parameterization for Higgs CP admixture and performs fits to data, providing new constraints on Higgs CP violation and mixing angles.

Findings

Pure CP-odd Higgs disfavored at 3 sigma

Sizable mixing angles still compatible with data

Future LHC runs can tighten CP mixing constraints

Abstract

In this paper, we constrain CP violation in the Higgs sector using the measured signal strengths in the various Higgs search channels. To this end, we introduce a general parameterization for a resonance which is an admixture of a CP-even Higgs-like state and a CP-odd scalar. By performing a fit to the available data from the Tevatron and LHC experiments one obtains constraints on the mixing angle and the couplings of the resonance to Standard Model fields. Depending on the couplings, sizable mixing angles are still compatible with the data, but small mixing is in general preferred by the fit. In particular we find that a pure CP-odd state is disfavored by the current data at the 3 sigma level. Additionally we consider a mixed fermiophobic resonance and a model with two degenerate mixed resonances and find that both scenarios can successfully fit the data within current errors. Finally, we estimate that the mixing angle can be constrained to \alpha < 1.1 (0.7) in the full 8 TeV (14 TeV) run of the LHC.