= MSSMD Model =

== Author ==
Wei Shi

Rice University, weishi[at]rice.edu

== Model Description ==
The model is based on MSSM, but adding a dark sector. The dark sector, ''U(1)D'', is broken, giving rise to light dark photons (''γD'') that weakly couple to the SM particles via a small kinetic mixing with photons. The lightest neutralino ''n1'' in MSSM is no longer stable and can decay via processes such as ''n1 → nD + γD'', where ''nD'' is a light dark neutralino (fermion). In this model, the ''γD'' is mediated by very weak interactions with the SM, and can decay to muon pairs promptly or non-promptly.

== References ==
[https://cds.cern.ch/record/2232052/files/HIG-16-035-pas.pdf]

[https://link.springer.com/content/pdf/10.1007/JHEP05(2010)077.pdf]

== Model Files ==
MSSMD implementation: [http://feynrules.irmp.ucl.ac.be/attachment/wiki/MSSMD/MSSMD.fr]

Parameter file: [http://feynrules.irmp.ucl.ac.be/attachment/wiki/MSSMD/sps1a.dat]

Example of a notebook to produce UFO model: [http://feynrules.irmp.ucl.ac.be/attachment/wiki/MSSMD/MSSMD.nb]

UFO model: [http://feynrules.irmp.ucl.ac.be/attachment/wiki/MSSMD/MSSMD_UFO.zip]

== Validation ==
The model is validated by checking kinematic distribution plots from the LHE file generated by MadGraph5.

[https://github.com/weishi10141993/DarkSUSY_MC_MG5/tree/master/MSSMDarkSector/MG5_0p25_cT_100_LHE]

[https://github.com/weishi10141993/DarkSUSY_MC_MG5/tree/master/MSSMDarkSector/MG5_8p5_cT_100_LHE]

== Acknowledgement ==
The author would like to thank ''F. Elahi'' and ''M. Abdullah'' for helpful discussions.  Thanks to ''B. Fuks'' for the help in the implementation. Thanks to ''O. Mattelaer'' for help interface with MadGraph5.