Di-Photon excess in the 2HDM: hasting towards the instability and the non-perturbative regime

TL;DR

This paper examines the two Higgs doublet model as an explanation for the di-photon excess, revealing that the required enhancements lead to potential instabilities and non-perturbative regimes due to additional fermions.

Contribution

It demonstrates that explaining the di-photon excess within the 2HDM involves large fermion contributions that destabilize the scalar potential before reaching non-perturbative hypercharge coupling.

Findings

Large fermion contributions cause potential instability.

The scalar potential becomes unstable before non-perturbative hypercharge coupling.

Explains limitations of 2HDM in accounting for the di-photon excess.

Abstract

We challenge the interpretation of the di-photon excess recently observed by both ATLAS and CMS in a two Higgs doublet framework. Due to the large enhancement necessary to obtain the observed di-photon signal, a large number of colored and charged vector-like fermions are called for. We find that even before the hypercharge gauge coupling becomes non perturbative, the one loop effects of these fermions abruptly drive the scalar potential to instability.