The SM extension with color-octet scalars: diphoton enhancement and global fit of LHC Higgs data

TL;DR

This paper evaluates the Manohar-Wise model, which extends the Standard Model with color-octet scalars, showing it can better fit LHC Higgs data and explain diphoton enhancement, especially with ATLAS results.

Contribution

It demonstrates that the Manohar-Wise model can significantly improve the fit to Higgs data and constrains its parameter space using current experimental results.

Findings

The model explains Higgs data with lower chi-squared than the SM.

Current Higgs data, especially from ATLAS, strongly constrain the model.

The model can account for the observed diphoton enhancement by reversing the sign of the hgg coupling.

Abstract

In light of the significant progress of the LHC to determine the properties of the Higgs boson, we investigate the capability of the Manohar-Wise model in explaining the Higgs data. This model extends the SM by one family of color-octet and isospin-doublet scalars, and it can sizably alter the coupling strengths of the Higgs boson with gluons and photons. We first examine the current constraints on the model, which are from unitarity, the LHC searches for the scalars and the electroweak precision data (EWPD).In implementing the unitarity constraint, we use the properties of the SU(3) group to simplify the calculation. Then in the allowed parameter space we perform a fit of the model, using the latest ATLAS and CMS data, respectively. We find that the Manohar-Wise model is able to explain the data with \chi^2 significantly smaller than the SM value. We also find that the current Higgs data, especially the ATLAS data, are very powerful in further constraining the parameter space of the model. In particular, in order to explain the diphoton enhancement reported by the ATLAS collaboration, the sign of the hgg coupling is usually opposite to that in the SM.