Collider Signatures of Type-X 2HDM + scalar singlet dark matter at HL-LHC

Abstract

As the 125 GeV Higgs becomes disfavored as a portal to the dark sector, one is motivated to look beyond the SM-Higgs sector, into extended scalar-mediated portal mechanisms. In this work we consider one interesting possibility of such extended scalar sector, namely Type X two Higgs doublet with a scalar singlet dark matter. This model with the advantage of light pseudoscalars also provides the explanation for the observed anomalous magnetic moment of muon. The dark matter phenomenology of this model is unique from the other types of two Higgs doublet models. Therefore, it is quite intriguing to look for signatures specific to this model at the collider experiments. In this work we take up the task of finding suitable final states and regions of parameters space that can be probed at the high-luminosity runs of LHC. We go beyond our rectangular cut-based approach and use Artificial Neural Network which shows remarkable improvement in terms of signal significance.

Two-Higgs-doublet models in light of current experiments: a brief review

“…Besides, in the L2HDM with a DM, the quark Yukawa couplings of H can be significantly suppressed for a very large b tan . If such a H field is taken as the portal between the SM sector and DM, the model can easily weaken the bound of the DM direct detection and explain the muon g − 2 [49,50]. The muon g − 2 is a very precisely measured observable and serves as a sensitive probe of new physics (for a pedagogical review, see, e.g.…”

“…If an additional field protected by a new symmetry is added to other types of 2HDMs, then these models also can provide a DM candidate. In these models, the multiple scalar fields can be the portals between the DM and the SM sector, and lead to some interesting effects on the DM observables via their various Yukawa couplings [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. On the other hand, the analyses of ATLAS and CMS collaborations at the LHC show that the properties of the discovered 125 GeV Higgs boson agree well with the SM Higgs boson [51,52].…”

Two-Higgs-doublet models in light of current experiments: a brief review

“…Besides, in the L2HDM with a DM, the quark Yukawa couplings of H can be significantly suppressed for a very large tan β. If such a H field is taken as the portal between the SM sector and DM, the model can easily weaken the bound of the DM direct detection and explain the muon g − 2 [47,48].…”

“…In the inert 2HDM, the lightest neutral component of the inert Higgs doublet field is stable and may be considered as a dark matter (DM) candidate. If a DM field is added to the 2HDM, the scalar fields, as the portals between the DM and the SM sector, can lead to some interesting effects on the DM observables via their various Yukawa couplings [32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48]. On the other hand, the analyses of ATLAS and CMS collaborations at the LHC show that the properties of the discovered 125 GeV Higgs boson agree well with the SM Higgs boson [49,50].…”