In several searches for additional Higgs bosons at the LHC, in particular the CMS search in the $pp \to \phi \to t \bar t$ channel and the ATLAS search in the $pp \to \phi \to \tau^+\tau^-$ channel, a local excess at the level of $3\,\sigma$ or above has been observed at a mass scale of $m_\phi \approx 400$~GeV. We investigate to what extent a possible signal in those channels could be accommodated in the Next-to-Two-Higgs-Doublet Model (N2HDM) or the Next-to Minimal Supersymmetric Standard Model (NMSSM). In a second step we furthermore analyse whether such a model could be compatible with both a signal at $\approx 400$~GeV and at $\approx 96$~GeV, where the latter possibility is motivated by observed excesses in searches for the $b \bar b$ final state at LEP and the di-photon final state at CMS. The analysis for the N2HDM reveals that the observed excesses at $\approx 400$~GeV in the observed excesses at $\approx 400$~GeV in the $pp \to \phi \to t \bar t$ and $pp \to \phi \to \tau^+\tau^-$ channels point towards different regions of the parameter space, while one such excess and an additional Higgs boson at $\approx 96$~GeV could simultaneously be accommodated. In the context of the NMSSM an experimental confirmation of a signal in the $t \bar t$ final state would favor the alignment-without-decoupling limit of the model, where the Higgs boson at $\approx 125$~GeV could be essentially indistinguishable from the Higgs boson of the SM. In contrast, a signal in the $\tau^+\tau^-$ channel would be correlated with significant deviations of the properties of the Higgs boson at $\approx 125$~GeV from the ones of a SM Higgs boson that could be detected with high-precision coupling measurements.
|Collaboration / Activity||theory|
|First author||Sven Heinemeyer|