Multi-Lepton Probes of the Drell-Yan Production of Triplet Higgses

TL;DR

This paper explores whether a Real Higgs Triplet model can explain observed excesses in triboson production at the LHC, finding it consistent but not favored over the Standard Model, with future data needed for clarification.

Contribution

It investigates the potential of the $ ext{Delta}$SM Higgs triplet model to account for LHC triboson excesses through electroweak scalar production and decay.

Findings

Current data shows a 2.6$\sigma$ preference for new physics.

The $ ext{Delta}$SM predicts more events than observed, aligning with data but not favoring it.

Future Run 3 and HL-LHC data could clarify the model's viability.

Abstract

Excesses in di-photon, $Z\gamma$, and $WW$ spectra indicate the existence of a new Higgs boson with mass $152 \pm 1$ GeV. However, no excess is observed in the $ZZ$ channel. This pattern aligns with a Real Higgs Triplet model with hypercharge $Y = 0$ ($\Delta$SM). A prediction of this model is the Drell--Yan production of scalars at the LHC, which dominantly decay to electroweak bosons, thus enhancing the cross sections of triboson channels such as $WWZ$, $WZZ$, and $WWW$. Interestingly, both ATLAS and CMS have reported higher-than-expected significances for such processes: $6.4\sigma$ (observed) vs $4.7\sigma$ (expected) in the $VVZ$ (where $V = W$ or $Z$) channel and $4.4\sigma$ vs $3.6\sigma$ in $WWZ$, suggesting the possibility that these signals may be manifestations of an extended Higgs sector. We investigate whether the $\Delta$SM can account for these triboson excesses through electroweak production and decay of triplet scalars. We find that while current data prefers a non-zero new physics signal ($2.6\sigma$), the $\Delta$SM predicts more events than observed, such that it is consistent with data but not preferred over the SM. However, this tension could be clarified with Run~3 and HL-LHC data.