# Anatomy of the Real Higgs Triplet Model

**Authors:** Saiyad Ashanujjaman, Sumit Banik, Guglielmo Coloretti, Andreas Crivellin, Siddharth P. Maharathy, Bruce Mellado  
**arXiv:** [2411.18618](https://arxiv.org/abs/2411.18618)  
**Date:** 2024-11-27  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/2411.18618v1/

## Key points

- The Standard Model is extended by a $Y=0$ real Higgs triplet in the $\Delta$SM
- Introduction of a $CP$-even neutral Higgs particle ($\Delta^0) and two charged Higgs bosons ($\Delta^\pm), with quasi-degeneracy in mass
- Theoretical constraints explored include vacuum stability and perturbative unitarity
- Calculations of various Higgs decays, including loop-induced modes like di-photon ($\gamma\gamma) and $Z\gamma)
- Behavior of $\Delta^0, which predominantly decays to $WW, but also has notable branching ratio to di-photon with minimal mixing between SM Higgs and $\Delta^0
- Model predicts positive shift in $W$ mass aligning well with current global electroweak fit observations
- Collider implications at LHC include stau-like signature, multi-lepton final states, associated di-photon production
- Recent experimental findings shed light on model validity through reinterpretations of supersymmetric tau partner searches, multi-lepton searches, and recasts of associated di-photon searches showing excesses around 152 GeV

## Summary

The Standard Model is extended by a $Y=0$ real Higgs triplet in the $\Delta$SM. This introduces a $CP$-even neutral Higgs particle ($\Delta^0$) and two charged Higgs bosons ($\Delta^\pm$), with quasi-degeneracy in mass. The authors explore theoretical constraints such as vacuum stability and perturbative unitarity before delving into calculations of various Higgs decays, including loop-induced modes like di-photon ($\gamma\gamma$) and $Z\gamma$. Of particular interest is the behavior of $\Delta^0$, which predominantly decays to $WW$, but also has a notable branching ratio to di-photon when there is minimal mixing between the SM Higgs and $\Delta^0$. The model predicts a positive shift in the $W$ mass, aligning well with current global electroweak fit observations. Moving on to collider implications at the Large Hadron Collider (LHC), several intriguing signatures emerge. These include a stau-like signature from processes like $pp\to \Delta^+\Delta^-\to \tau^+\tau^-\nu\bar\nu$, multi-lepton final states from reactions like $pp\to \gamma^*\to \Delta^+\Delta^-\to W^+W^-ZZ$, and associated di-photon production from events such as $pp\to W^{*} \to \Delta^\pm(\Delta^0\to\gamma\gamma)$. Recent experimental findings shed light on the validity of the model. For instance, reinterpretations of supersymmetric tau partner searches by ATLAS and CMS exclude certain mass ranges for $\Delta^\pm$, while multi-lepton searches provide bounds close to predicted cross-sections. Additionally, recasts of associated di-photon searches reveal intriguing results, with some signal regions showing excesses around 152 GeV, hinting at a non-zero di-photon branching ratio with significant statistical significance. Overall, this detailed analysis sheds light on the nuances of the Real Higgs Triplet Model and its implications for particle physics research at colliders like the LHC.