== Model description

The Chern-Simons portal adds a new vector particle with zero electric charge, the X boson, interacting with the Standard Model gauge bosons - W, Z, [[latex( $\gamma$ )]] via pseudo Chern-Simons current. The low energy effective interaction has the form

 [[latex( $\mathcal{L}_{X} = \mathcal{L}_{X,\text{kin}}+\epsilon^{\mu\nu\alpha\beta}\left(W_{\mu}X_{\nu}\partial_{\alpha}WY{\dagger}_{\beta}+\text{h.c.} + c_{Z}Z_{\mu}X_{\nu}\partial_{\alpha}Z_{\beta}+c_{Z\gamma}Z_{\mu}X_{\nu}\partial_{\alpha}A_{\beta}\right) )]]



 [[latex( $\mathcal{O}_{R} = \!\left( \bar{t}_R \gamma^\mu t_R \right) \!\left( \bar{t}_R \gamma_\mu t_R \right)$ )]]

== Implementation description

The model has been implemented using merging of SM.fr and ChernSimons.fr files. The implementation introduces one real new vector particle - X boson with the name xb. The implementation contains 6 new parameters: the coupling to W bosons cW (default value: 0.001), the coupling to Z bosons cZ (default value: 0.001), the coupling to the Z boson and photon cZgamma (default value: 0.001), the non-minimal coupling to muons Cmu (default value: 0.1), the X boson mass Mxb (default value: 1 in units of GeV), the X boson width Wxb (default value: 1 in units of GeV). The implementation is performed in the unitary gauge. The implementation format is the UFO format. 

== How to use the model in MadGraph

To use the model, unpack the .zip archive and move the resulting folder ChernSimons_UFO to the directory /models of your MadGraph directory.

== Files
=== Model files
* ChernSimons.fr : this is the main file. 
* ChernSimons.nb : this is an example Mathematica notebook that loads the model, calculates Feynman rules and makes the UFO implementation. Note that it requires the implementation of the model file of the SM implementation of FeynRules.
=== Implementation
*ChernSimons_UFO.zip

== List of studies used this implementation
 * [https://arxiv.org/abs/1903.11918 Probing new physics with displaced vertices: muon tracker at CMS]

== References

Please cite [1] for the model file

* K. Bondarenko, A. Boyarsky, M. Ovchynnikov, O. Ruchayskiy, L. Shchutska. ''Probing new physics with displaced vertices: muon tracker at CMS''. [https://arxiv.org/abs/1903.11918 hep-ph/1903.11918]

[[latex( $$\gamma^\mu \delta^{\mu} f^{\rho} g^{\delta} = \!\left( \right) $$ )]]