The
The FeynRules file vSMEFT_Higgs-N.fr extends the default SM model file and the HeavyN model file with dimension-5 and dimension-6 Higgs-SM_v_Majorana.fr neutrinos are set to be Majorana (SelfConjugate -> True). This is the only difference with respect to the default SM model file SM.fr supplied with FeynRules.
The Mathematica notebook vSMEFT_Higgs-N_UFO.nb loads and merges the FeynRules models SM_v_Majorana.fr and vSMEFT_Higgs-N.fr, performs a number of sanity checks, computes Feynman rules and generates the corresponding UFO model vSMEFT_Higgs-N_UFO (also available as a zip file vSMEFT_Higgs-N_UFO.zip). The latter can be used to perform simulations with MadGraph5_aMC@NLO.
The present model files are largely based on those originally developed in Ref. 1. Their description is provided in Ref. 2. If you use the model files, please cite these references.
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J. M. Butterworth, M. Chala, C. Englert, M. Spannowsky and A. Titov, Higgs phenomenology as a probe of sterile neutrinos, Phys. Rev. D 100 (2019) 115019 [arXiv:1909.04665].
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A. Titov, FeynRules and UFO model files for
$\nu$ SMEFT: Higgs-$N_R$ operators of dimensions five and six, arXiv:2511.10733.