## What is/are Higgs Singlet?

Higgs Singlet - We also consider three particular Beyond-the-Standard-Model (BSM) scenarios – namely a typical scenario of an Inert Doublet Model (IDM), and scenarios of a Two-Higgs-Doublet Model (2HDM) and of a Higgs Singlet Model (HSM) without scalar mixing – and we include all the necessary finite counterterms to obtain (in addition to $$\overline{{\mathrm{MS}}}$$ MS ¯ results) on-shell scheme expressions for the corrections to the Higgs self-couplings.^{[1]}We propose a supersymmetric extension of the anomaly-free and three families nonuniversal $U(1)$ model, with the inclusion of four Higgs doublets and four Higgs singlets.

^{[2]}The N2HDM is an extension of the Standard Model by a Higgs doublet and a real Higgs singlet.

^{[3]}We review the interpretation of this possible signal as a Higgs boson in the 2~Higgs Doublet Model with an additional real Higgs singlet (N2HDM).

^{[4]}If a dark Higgs singlet also exists, then this breaks the U(1) d symmetry, allowing for Higgs mixing (parametrised by ) between the SM and dark sector Higgs bosons, and thereby opening the Higgs portal as a discovery channel.

^{[5]}We illustrate this point by taking three new physics models for example: (i) models with additional isospin singlet scalars, (ii) a model with an extra real Higgs singlet, and (iii) a classically conformal B-L model.

^{[6]}We propose a natural realization of linear seesaw model with hidden gauge symmetry in which $SU(2)_L$ triplet fermions, one extra Higgs singlet, doublet and quartet scalar are introduced.

^{[7]}

## Real Higgs Singlet

The N2HDM is an extension of the Standard Model by a Higgs doublet and a real Higgs singlet.^{[1]}We review the interpretation of this possible signal as a Higgs boson in the 2~Higgs Doublet Model with an additional real Higgs singlet (N2HDM).

^{[2]}We illustrate this point by taking three new physics models for example: (i) models with additional isospin singlet scalars, (ii) a model with an extra real Higgs singlet, and (iii) a classically conformal B-L model.

^{[3]}