== Author

Maksym Ovchynnikov (maksym.ovchynnikov@cern.ch).

== Model description

The Chern-Simons portal extends the Standard Model by adding a new vector particle with zero electric charge, the X boson, interacting with the Standard Model electroweak gauge bosons, W, Z, [[latex( $\!\gamma$ )]], via pseudo Chern-Simons current. After acquiring the Higgs VEV, the interaction has the form [#ref1 [1]][#ref2 [2]]

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


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


== Implementation and usage description

The model has been implemented using merging of [https://feynrules.irmp.ucl.ac.be/wiki/StandardModel SM.fr] and [https://feynrules.irmp.ucl.ac.be/attachment/wiki/ChernSimonsPortal/Chern-Simons-Portal.fr Chern-Simons-Portal.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 axial-vector 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. 

To use the model, unpack the [https://feynrules.irmp.ucl.ac.be/attachment/wiki/ChernSimonsPortal/ChernSimons_UFO.zip ChernSimons_UFO.zip] archive and move the resulting folder '''ChernSimons_UFO''' to the directory '''/models''' of your [https://feynrules.irmp.ucl.ac.be/wiki/MadGraphInterface MadGraph] directory.

== Files
* [https://feynrules.irmp.ucl.ac.be/attachment/wiki/ChernSimonsPortal/Chern-Simons-Portal.fr Chern-Simons-Portal.fr]: this is the main file. 
* [https://feynrules.irmp.ucl.ac.be/attachment/wiki/ChernSimonsPortal/ChernSimons.nb 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.
* [https://feynrules.irmp.ucl.ac.be/attachment/wiki/ChernSimonsPortal/ChernSimons_UFO.zip ChernSimons_UFO.zip]: UFO format implementation for [https://feynrules.irmp.ucl.ac.be/wiki/MadGraphInterface MadGraph].
== List of studies used this implementation
 *  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]

== References

Please cite [#ref3 [3]] when using the model file.

* [=#ref1] [1] I. Antoniadis, A. Boyarsky, S. Espahbodi, O. Ruchayskiy, J.D. Wells. ''Anomaly driven signatures of new invisible physics at the Large Hadron Collider''. [https://arxiv.org/abs/0901.0639 hep-ph/0901.0639]

* [=#ref2] [2] S. Alekhin et.al. ''A facility to Search for Hidden Particles at the CERN SPS: the SHiP physics case''. [https://arxiv.org/abs/1504.04855 hep-ph/1504.04855]

* [=#ref3] [3] 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]