The THDMa is a new physics model that extends the scalar sector of the Standard Model by an additional doublet as well as a pseudoscalar singlet and allows for mixing between all possible scalar states. In the gauge eigenbasis, the additional pseudoscalar serves as a portal to the dark sector, with a priori any dark matter spin states. The option where dark matter is fermionic is currently one...
The Inert Doublet Model (IDM) is one of the simplest SM extensions and introduces four new scalar particles: H$^\pm$, A and H; the lightest, H, is stable and hence it is a natural dark matter (DM) candidate. A set of benchmark points is considered, which are consistent with current theoretical and experimental constraints and promise detectable signals at future colliders. Discovery reach for...
We analyze the possible size of various triple Higgs couplings in the 2HDM (type I and II), allowed by all current theoretical and experimental constraints. We discuss how one can get access to them at future $e^+e^-$ with a center-of-mass energy of 500 GeV or more.
Models with scalar doublets and charged scalar singlets have the interesting property that they have couplings between one $Z$ boson and two charged scalars of different masses. This property is often ignored in phenomenological analysis, as it is absent from models with only extra scalar doublets. We explore this issue in detail, considering $h \rightarrow Z \gamma$, $B \to X_s \gamma$, and...
We analyze the possible realization of a 96 GeV Higgs boson describing the "excesses" observed at CMS in the di-photon decay channel and at LEP in the $b \bar b$ decay channel. We compare the realizations in the 2DMD with an additional real singlet (N2HDM) or a complex singlet (2HDMS). We discuss how these realizations can possibly resolved at future high-energy $e^+e^-$ colliders.
We examime models with extended Higgs sectors in the light of recent excesses in the BSM Higgs-boson searches at the LHC. We discuss the possibilities to investigate these scenarios at a future e+e- collider (with a special emphasis on the ILC).
