Multi-lepton probes of the Drell-Yan production of triplet higgses

Abstract Excesses in di-photon, $$Z\gamma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>Z</mml:mi> <mml:mi>γ</mml:mi> </mml:mrow> </mml:math> , and WW spectra indicate the existence of a new Higgs boson with mass $$152\pm 1$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>152</mml:mn> <mml:mo>±</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:math> GeV. However, no excess is observed in the ZZ channel. This pattern aligns with a Real Higgs Triplet model with hypercharge $$Y = 0$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>Y</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0</mml:mn> </mml:mrow> </mml:math> ( $$\varDelta \hbox {SM}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>Δ</mml:mi> <mml:mtext>SM</mml:mtext> </mml:mrow> </mml:math> ). 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: $$6.4\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>6.4</mml:mn> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> (observed) vs $$4.7\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>4.7</mml:mn> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> (expected) in the VVZ (where $$V = W$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>V</mml:mi> <mml:mo>=</mml:mo> <mml:mi>W</mml:mi> </mml:mrow> </mml:math> or Z ) channel and $$4.4\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>4.4</mml:mn> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> vs $$3.6\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>3.6</mml:mn> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> in WWZ , suggesting the possibility that these signals may be the manifestations of an extended Higgs sector. We investigate whether the $$\varDelta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Δ</mml:mi> </mml:math> 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 ( $$2.6\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>2.6</mml:mn> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> ), the $$\varDelta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Δ</mml:mi> </mml:math> 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.