Abstract
The N2HDM is based on the CP-conserving 2HDM extended by a real scalar singlet field. Its enlarged parameter space and its fewer symmetry conditions as compared to supersymmetric models allow for an interesting phenomenology compatible with current experimental constraints, while adding to the 2HDM sector the possibility of Higgs-to-Higgs decays with three different Higgs bosons. In this paper the N2HDM is subjected to detailed scrutiny. Regarding the theoretical constraints we implement tests of tree-level perturbativity and vacuum stability. Moreover, we present, for the first time, a thorough analysis of the global minimum of the N2HDM. The model and the theoretical constraints have been implemented in ScannerS, and we provide N2HDECAY, a code based on HDECAY, for the computation of the N2HDM branching ratios and total widths including the state-of-the-art higher order QCD corrections and off-shell decays. We then perform an extensive parameter scan in the N2HDM parameter space, with all theoretical and experimental constraints applied, and analyse its allowed regions. We find that large singlet admixtures are still compatible with the Higgs data and investigate which observables will allow to restrict the singlet nature most effectively in the next runs of the LHC. Similarly to the 2HDM, the N2HDM exhibits a wrong-sign parameter regime, which will be constrained by future Higgs precision measurements.
Highlights
Electroweak symmetry breaking (EWSB) like in composite Higgs models [5,6,7,8,9,10,11,12,13,14,15,16]
The model and the theoretical constraints have been implemented in ScannerS, and we provide N2HDECAY, a code based on HDECAY, for the computation of the Next-to-Minimal 2HDM (N2HDM) branching ratios and total widths including the state-ofthe-art higher order QCD corrections and off-shell decays
In this paper we have investigated the N2HDM, which is based on the CP-conserving 2-Higgs-doublet model (2HDM) extended by a real scalar singlet field
Summary
The N2HDM is based on the CP-conserving (or real) 2HDM with a softly broken Z2 symmetry extended by a real singlet field ΦS. In terms of the two SU(2)L Higgs doublets Φ1 and Φ2 and the singlet field ΦS, the N2HDM potential is given by. Replacing the doublet and singlet fields in the Higgs potential by the parametrisations (2.4) the mass matrices in the gauge basis are obtained from the second derivatives with respect. Introducing a real singlet field with a VEV, the charged and pseudoscalar sectors of the model remain unchanged with respect to the 2HDM. In order to avoid tree-level FCNCs we extend the Z2 symmetry (2.2) to the Yukawa sector This leads to the same four types of doublet couplings to the fermions as in the 2HDM. We obtain the effective coupling factors c(Hif f ) in terms of the mixing matrix elements Rij and the mixing angle β provided in table 4.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
