Last modified 6 years ago Last modified on 04/02/11 23:08:11

SM + Scalars


  • Claude Duhr
    • IPPP Durham
    • claude.duhr@…

Description of the model

This model is an extension of the SM, where a new scalar sector is added. This new sector consists in an O(n) symmetric model that only interacts with itself and with the SM Higgs boson.

The implementation of the model is based on

" The minimal non-minimal Standard Model ", J.J. van der Bij, Phys.Lett.B636:56-59,2006, hep-ph/0603082.

Model files

  • This is the main file.
  • This model needs the model file of the SM implementation of FeynRules. Note that the width of the Higgs boson in the SM model file needs to be changed.
  • SMScalars.nb : This is an example Mathematica notebook that loads the model and calculates Feynman rules.

The Feynman rules and the particle content are summarized in the following pdf file.


The model is loaded by merging the model files and

The implmentation allows for the use of the Feynman gauge in the SM.The switch between the two gauge is achieved via FeynmanGauge = True/False (see StandardModel).

The number of new scalars in the O(n) symmetric sector can be changed. This can be achieved by changing the variable Nf inside the model file before loading the model. The default value is Nf = 4.

Matrix element generator files

Below we give tarballs containing the model files generated by FeynRules for the various matrix element generaotrs for which a FeynRules interface exists. All fermion masses are put to zero, except for the top, the bottom and the Tau lepton masses. All files are in unitary gauge.

SM_Plus_Scalars-CH.tgzThe model files for CalcHep.
SM_Plus_Scalars_FA.tgzThe model files for FeynArts.
SM_Plus_Scalars_MG.tgzThe model files for MadGraph 4.
SM_Plus_Scalars_SH.tgzThe model files for Sherpa.
SM_Plus_Scalars_UFO.tgzThe model files in UFO format (e.g. for MadGraph 5).