Vacuum Stability and Higgs Diphoton Decay Rate in the Zee-Babu Model

TL;DR

This paper investigates how the Zee-Babu model can address the Higgs diphoton decay excess and vacuum stability issues, finding that additional modifications are likely needed to satisfy both constraints simultaneously.

Contribution

It analyzes the compatibility of vacuum stability and diphoton decay rate enhancement within the Zee-Babu model, highlighting the need for new ingredients to resolve both issues.

Findings

Difficulty in simultaneously satisfying vacuum stability and diphoton enhancement constraints.

Overlapping parameter regions are hard to find without additional model ingredients.

Additional new physics may be necessary to address both issues together.

Abstract

Although recent Higgs data from ATLAS and CMS are compatible with a Standard Model (SM) signal at $2\sigma$ level, both experiments see indications for an excess in the diphoton decay channel, which points to new physics beyond the SM. Given such a low Higgs mass $m_H \sim 125 {\rm GeV}$, another sign indicating the existence of new physics beyond the SM is the vacuum stability problem, i.e., the SM Higgs quartic coupling may run to negative values at a scale below the Planck scale. In this paper, we study the vacuum stability and enhanced Higgs diphoton decay rate in the Zee-Babu model, which was used to generate tiny Majorana neutrino masses at two-loop level. We find that it is rather difficult to find overlapping regions allowed by the vacuum stability and diphoton enhancement constraints. As a consequence, it is almost inevitable to introduce new ingredients into the model, in order to resolve these two issues simultaneously.