4th Generation Model

Author

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

Description of the model

This model is an extension of the SM, where a new fourth generation of fermions, a t' and a b' with SM couplings, is added. The CKM matrix is parametrized by Vtps and Vtpb, which are supposed small, and to leading order in the expansion in Vtps and Vtpb it is given by,

   1        0           0           0
   0   1-Vtps^2/2       0          Vtps
   0   -Vtps Vtpb   1-Vtpb^2/2     Vtpb
   0     -Vtps        -Vtpb       1-Vtps^2/2 -Vtpb^2/2

The particle content and the vertices of the model are summarized in the following pdf file.

Model files

• 4Gen.fr: This is the main file.
• 4Gen.nb: This is an example Mathematica notebook that loads the model and calculates Feynman rules.

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. Furthermore, in the CalcHep files, the CKM matrix is real.

4th_Generation_Complex_CKM-CH.tgz	The model files for CalcHep.
4th_Generation_Complex_CKM_FA.tgz	The model files for FeynArts.
4th_Generation_Complex_CKM_MG.tgz	The model files for MadGraph 4.
4th_Generation_Complex_CKM_SH.tgz	The model files for Sherpa.
4th_Generation_Complex_CKM_UFO.tgz	The model files in UFO format (e.g. for MadGraph 5).