Growing Evidence for a Higgs Triplet

TL;DR

This paper presents evidence for a new Higgs triplet particle around 152 GeV, combining multiple channels and recent LHC data, suggesting a significant potential discovery in particle physics.

Contribution

The study introduces a simple, predictive Higgs triplet model that explains recent LHC observations and provides the strongest statistical evidence for a new resonance at 152 GeV.

Findings

Significance of 4.3σ for a 152 GeV resonance

Combined analysis of di-photon channels from ATLAS data

Supports existence of a Higgs triplet with implications for W-boson mass

Abstract

Despite intensive searches at the LHC, no new fundamental particle has been discovered since the discovery of the 125 GeV Higgs boson. In general, a new physics discovery is challenging without a UV-complete model because different channels and observables cannot be combined directly and unambiguously. Moreover, without indirect hints for new particles, the parameter space to be searched is huge, resulting in diminished significance due to the look-elsewhere effect. Several LHC searches with multiple leptons in the final state point towards the existence of a new Higgs boson with a mass in the 140-160 GeV range, decaying mostly to a pair of W bosons. This dominant decay mode motivates a Higgs triplet with zero hypercharge, which also predicts a heavier-than-expected $W$-boson as indicated by the CDF-II measurement. Within this simple and predictive model, we simulate and combine channels of associated di-photon production. Considering the run-2 results of ATLAS, including those presented recently at the Moriond conference, a significance of 4.3$\sigma$ is obtained for a mass of 152 GeV. This is the largest statistical evidence for a new narrow resonance observed at the LHC.