The BSM Characterisation model

Authors

• Benjamin Fuks (LPTHE Paris)
• Kentarou Mawatari (LPSC Grenoble)
  • Emails: fuks @ lpthe.jussieu.fr, kentarou.mawatari @ lpsc.in2p3.fr

Description of the model

The BSM Characterisation (BSMC) model is an extension of the Higgs Characterisation (HC) model and is based on the Standard Model (SM) effective-field-theory (EFT) Lagrangian in the mass-eigen basis.

We adopt the notation of the Lagrangian in the Higgs basis proposal for LHC HXSWG and additionally consider all couplings external parameters that can be tuned according to the needs of the user. More information on the parameterization can be found on ​the HXSWG page. All the coefficients of the operators in the BSMC model are hence implemented as external parameters in the FeynRules implementation (i.e. independent parameters), although a large fraction of them are dependent as soon as one considers a gauge-invariant set of independent operators in the SM EFT, as done e.g. in the Warsaw or SILH bases. The translation of the coefficients from those bases to the Higgs basis can be done by ​Rosetta, and an output parameter card from Rosetta can be used as an input card for FeynRules and for event generators (e.g. MadGraph5_aMC@NLO), with the BSMC model file. See more details in

• ​1508.05895 : A. Falkowski, B. Fuks, K. Mawatari, K. Mimasu, F. Riva, V. Sanz, "Rosetta: an operator basis translator for Standard Model effective field theory".

Model files

• BSMC.fr : The main model file.
• SM_BSMC.fr : This model requires the modified SM implementation of FeynRules.
• Massless.rst: restriction files tha can be possibly used.
• BSMC.nb : This is an example Mathematica notebook that loads the model, calculates the Feynman rules and extract the model files within the UFO format.
• BSMC.ufo.tgz : The model files in UFO format (for, e.g. MadGraph5_aMC@NLO) (v2.1).

Version updates

• 16.07.2018 - v2.2: Bug in the dipole operators + normalization of one operator (thanks G. Durieux, Marc Riembau and Thibaud Vantalon)
• 31.05.2017 - v2.1: change of the signs of the SM Hgg, HaZ and Haa couplings (thanks to S. Di Vita).
• 11.03.2016 - v2.0: version corresponding to the Rosetta paper ​1508.05895.
• 30.07.2015 - v1.1: modification of the handling of the flavor structure. Update to the Higgs basis note of Aug/15.
• 14.07.2015 - v1.0: release version (based on the Higgs basis note (Jun/14)).