== Author

Maksym Ovchynnikov (maksym.ovchynnikovATcern.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, and photon, via pseudo Chern-Simons current [#ref1 [1]][#ref2 [2]]. Brief description of the model is given in the [https://feynrules.irmp.ucl.ac.be/attachment/wiki/ChernSimonsPortal/Chern_simons_portal__brief_description.pdf​ file].

== 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 SM model file of the [https://feynrules.irmp.ucl.ac.be/wiki/StandardModel 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].

== 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]