Confronting the broken phase N2HDM with Higgs Data

Abstract

The broken phase of the Next-to two-Higgs-doublet model (N2HDM) constitutes an archetype of extended Higgs sectors. In the presence of a softly-broken $\mathrm{Z}_2$ symmetry throughout the scalar and Yukawa sectors, as the additional gauge singlet field does not interact with fermions, the model admits four variants of Yukawa interactions between the doublets and Standard Model fermions. We confront each type with experimental Higgs data, especially from CMS and ATLAS detectors at the LHC. Interfacing the models with the the state-of-the-art package $\mathtt{HiggsTools}$, we perform a statistical $\chi^2$ analysis to determine the best-fit points and exclusion limits at the $95\%$ and $68\%$ C.L., and identify SM-like Higgs measurements that affect each type the most. We further analyze the exclusion bounds on the additional Higgs bosons at the $95\%$ C.L., paying special attention to searches of hypothetical non-SM Higgs resonances decaying into a pair of bosons or fermions. We show regions where the additional Higgs bosons do not satisfy the narrow-width approximation utilized in most experimental searches.