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

Abstract

Excesses in di-photon, $Z{\hat{I}}^3$, 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 $Y=0$ ($\hat{I}”$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: $6.4\ddot{I}ƒ$ (observed) vs $4.7\ddot{I}ƒ$ (expected) in the $VVZ$ (where $V=W$ or $Z$) channel and $4.4\ddot{I}ƒ$ vs $3.6\ddot{I}ƒ$ in $WWZ$, suggesting the possibility that these signals may be manifestations of an extended Higgs sector. We investigate whether the $\hat{I}”$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 ($2.6\ddot{I}ƒ$), the $\hat{I}”$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.

published version in EPJC