# Internal BSM Models¶

A large number of BSM models are included in the Herwig release.

- A number of
**supersymmetric models**are implemented.- The
**Minimal Supersymmetric Standard Model (MSSM)**is the minimal supersymmetric extension of the Standard Model. The parameters for the model are set in`MSSM.model`

, an example of running the model for the LHC is provided in`LHC-MSSM.in`

and for a future linear collider in`ILC-MSSM.in`

. This model provides the basis for the implementation of all the other supersymmetric models which inherit from it. - The
**Next-to-Minimal Supersymmetric Standard Model (NMSSM)**includes an additional Higgs singlet field. The implementation inherits from that for the MSSM. The parameters for the model are set in and`NMSSM.model`

and an example of running the model for the LHC is provided in`LHC-NMSSM.in`

. - The
**R-parity violating**extension to the MSSM is implemented. Currently either bi-linear R-parity violating couplings, with parameters set in`RPV-Bi.model`

, or tri-linear R-parity violating couplings, with parameters set in`RPV-Tri.model`

, are allowed but not both simultaneously. An example of running either model for the LHC is provided in`LHC-RPV.in`

.

- The

The parameters for all these models can be read from SUSY Les Houches Accord (SLHA) files via the`setup`

command.

- Four extra-dimensional models are implemented.
- In the
**Large-Extra dimensions**model of Arkani-Hamed, Dimopoulos, and Dvali**(ADD)**only the gravitational force extents into the extra dimension which leads to the production of towers of graviton states as either missing transverse energy or changes to Standard Model processes due to the exchange of graviton towers. The parameters for the model are set in the`ADD.model`

file and an example of running the model for the LHC is provided in`LHC-ADD.in`

. - As with the ADD model in the
**Randell-Sundrum**model only gravity propagates in the extra dimension, however due the warped extra dimension in this case graviton resonances are produced. The parameters for the model are set in`RS.model`

, an example of running the model for the LHC is provided in`LHC-RS.in`

and for a future linear collider in`ILC-RS.in`

. - In the
**Minimal Universal Extra-Dimensions (MUED)**model all the field propagate in the extra dimension leading to towers of Kaluza-Klein states. The parameters for the model are set in`MUED.model`

, an example of running the model for the LHC is provided in`LHC-MUED.in`

and for a future linear collider in`ILC-MUED.in`

. - A model for
**transplankian scattering**which only requireas a new`MatrixElement`

for the scattering process. An example of running the model for the LHC is provided in`LHC-TRP.in`

.

- In the
- Two Little-Higgs models based on the idea that the Higgs boson is a pseudo-Goldstone boson arising from some global symmetry breaking at a TeV energy scale are implemented.
- The standard
**Little-Higgs**model with an extra top quark is implemented with the additional parameters for the model set in`LH.model`

and an example of running the model for the LHC is provided in`LHC-LH.in`

. - The
**Little-Higgs Models with T-parity**conservation leading to additional parameters for all the Standard Model particles. The parameters for the model are set in`LHTP.model`

and an example of running the model for the LHC is provided in`LHC-LHTP.in`

.

- The standard
- A model for
**Leptoquarks**. The parameters for the model are set in`Leptoquark.model`

and an example of running the model for the LHC is provided in`LHC-LQ.in`

. - A model for the production of either scalar or vector diquarks in the
**Sextet**representation of QCD. The parameters for the model are set in`Sextet.model`

and an example of running the model for the LHC is provided in`LHC-Sextet.in`

. - A model designed to try and explain the top forward-backward asymmetry observed by CDF. The parameters for the model are set in
`TTBA.model`

, an example of running the model for the LHC is provided in`LHC-TTBA.in`

and for the Tevatron in`TVT-TTBA.in`

. - A model including a \(Z'\) boson. The parameters for the model are set in
`Zprime.model`

and an example of running the model for the LHC is provided in`LHC-ZP.in`

.

## Implementing New Models¶

While we would now strongly recommend that any new models are added using the UFO interface it is possible to implement them directly in Herwig. Two examples are given below.