Combined Explanation of LHC Multi-Lepton, Di-Photon and Top-Quark Excesses
Guglielmo Coloretti, Andreas Crivellin, Bruce Mellado
The LHC analyses of processes containing two or more leptons and missing energy, possibly in association with b-jets, show strong tensions with the Standard Model predictions and are known as multi-lepton anomalies. In particular, top-quark differential distributions point towards the associated production of new Higgs bosons decaying into bottom quarks and W bosons (>5σ) with masses consistent with the di-photon excesses at 95GeV and 152GeV (3.8σ and 4.9σ, respectively). Furthermore, CMS found indications for resonant top-quark pair production at 400GeV (3.5σ) and both ATLAS and CMS reported elevated four-top and ttW cross-sections. In this article, we propose a combined explanation of these excesses by supplementing the SM Higgs with a second scalar doublet, a real scalar singlet (S) and a Higgs triplet with Y=0 (Δ); the Δ2HDMS. We fix the masses of the neutral triplet-like and the singlet-like scalars by the di-photon excesses, i.e. mΔ0=152 GeV and mS=95 GeV, respectively. Here, H, the CP-even component of the second doublet, is produced via gluon fusion from a top-loop and decays dominantly to S+Δ0 whose subsequent decays to WW and bb explain the differential top-quark distributions for σ(pp→H→SΔ0)≈6pb. Fixing the top-Yukawa accordingly, the CP-odd Higgs boson A turns out to have the right production cross-section to account for the resonant top-pair excess at 400GeV, while the top-associated production of H and A results in new physics pollution of Standard Model ttW and four-top cross sections, as preferred by the data. Furthermore, a positive shift in the W mass is naturally induced by the vacuum expectation value of the triplet and we show that the most relevant signal strengths of the 152GeV boson are compatible with the process pp→H→Δ0S if S is allowed to decay invisibly.