Degenerate Higgs bosons decays to ${\gamma\gamma}$ and ${Z\gamma}$ in the type II Seesaw Model

TL;DR

This paper investigates how degenerate Higgs bosons in the type II Seesaw Model affect the decay channels to gamma gamma and Z gamma, aligning with recent CMS and ATLAS results, and explores parameter constraints and potential signals of new particles.

Contribution

It provides a detailed analysis of Higgs decay modes in the type II Seesaw Model, highlighting possible deviations from the Standard Model and constraining model parameters based on experimental data.

Findings

Enhanced diphoton decay consistent with CMS/ATLAS data

Potential deviation in Z gamma decay with ratio ~1.6

Light doubly charged Higgs favored by current data

Abstract

Using the most recent results of CMS and ATLAS, we study the Higgs decays to $\gamma\gamma$ and $Z\gamma$ in the scenario where the two CP even Higgs predicted by the type II seesaw model (HTM) are close to mass degenerate with a mass near $125$ GeV. We analyse the effects of the Higgs potential parameters constrained by the full set of perturbative unitarity, boundedness from below (BFB) as well as from precision electroweak measurements on these decay modes. Our analysis demonstrates that the observed excess in the diphoton Higgs decay channel can be interpreted in our scenario within a delineated region controlled by $\lambda_{1}$ and $\lambda_{4}$ coupling. We also find a deviation in the Higgs decay to $Z\gamma$ with respect to the Standard Model prediction and the largest enhancement is found for a ratio $R_{Z\gamma}$ of the order $1.6$. Furthermore we show that consistency with current ATLAS data on the diphoton decay channel favours a light doubly charged Higgs with mass in the range $92 - 180$~GeV. Finally, we find that the $\gamma\gamma$ and $Z \gamma$ Higgs decay modes are generally correlated and the magnitude of correlation is sensitive to the sign of the $\lambda_{1}$ parameter.