= Type III Seesaw = == Authors == * Carla Biggio * Institut de Fisica d'Altes Energies (IFAE), Universitat Autonoma de Barcelona (UAB), Spain * email: biggio _at_ ifae.es * Florian Bonnet * Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Padova, Italy * email: florian.bonnet _at_ physik.uni-wuerzburg.de == Model Description == This model describes the minimal realisation of the Type III Seesaw. It is an extension of the Standard Model where a fermionic triplet is added to the matter content in order to give mass to one neutrino via a seesaw mechanism. The fermionic triplet is introduced under the form of a heavy Dirac charged lepton tr^+/-^ and a heavy Majorana neutral lepton tr^0^. For an exhaustive description of the model, see references below. == References == * "mu->e gamma and tau->l gamma decays in the fermion triplet seesaw", A. Abada, C. Biggio, F. Bonnet, B. Gavela, T. Hambye, Phys. Rev. D78 (2008) 033007 [arXiv:0803.0481] * "Implementation of the Type III Seesaw model in FeynRules/MadGraph and prospects for discovery with early LHC data", C. Biggio, F. Bonnet, [http://arxiv.org/abs/1107.3463 arxiv:1107.3463] == Model Files == * [http://feynrules.irmp.ucl.ac.be/attachment/wiki/TypeIIISeeSaw/typeIIIseesaw1.0.fr typeIIIseesaw1.0.fr]: this is the file containing the model * For `MadGraph/MadEvent` and BRIDGE users: [http://feynrules.phys.ucl.ac.be/attachment/wiki/TypeIIISeeSaw/formats.inc formats.inc]: this is a modified version of the file formats.inc, that can be useful when dealing with small mixing angles (the original file sets to zero couplings smaller than 10^-5^) * [http://feynrules.irmp.ucl.ac.be/attachment/wiki/TypeIIISeeSaw/typeIIIseesaw.nb typeIIIseesaw.nb]: this is a Mathematica notebook that loads the model and export it to the `MadGraph` and `CalcHep` format. == Validation == In order to validate the implementation of the model we have checked several processes: * Comparison with the `FeynRules` generated Standard Model in `MadGraph` (`sm_FR`) of SM 2-to-2 processes : * l^+^l^-^ -> ll * l^+^l^-^ -> VV * VV -> VV * HH -> VV * GG -> GG * qq~ -> qq~ * qq~ -> VV * qq~ -> GG * Comparison with the `FeynRules` generated Standard Model in `MadGraph` (`sm_FR`) of SM particles decay widths and branching ratios calculated with [http://www.lepp.cornell.edu/Research/TPP/BridgeSoftware.html BRIDGE] * Comparison with the theoretical predictions of the branching ratios calculated with [http://www.lepp.cornell.edu/Research/TPP/BridgeSoftware.html BRIDGE] * Comparison with previous studies (see [http://arxiv.org/pdf/0805.1613 Phys.Rev D78 (2008) 033002]) of the production cross section of a pair of triplets at the LHC with 14 TeV as center-of-mass energy: * pp -> tr^+^tr^^-^ * pp -> tr^+/-^tr^0^ Details of the validation procedure can be found on [http://arxiv.org/abs/1107.3463 arxiv:1107.3463]. == Software == The model has been tested on the following machines configurations: * iMac Intel Core 2 Duo, Mac OS X 10.6.6, FeynRules v1.4.3/FeynRulesv1.6beta, Mathematica 8 * Mac Book Intel Core Duo, Mac OS X 10.4.11, FeynRules v1.4.3, Mathematica 6 We also checked the compatibility of our model with Madgraph version 4 and version 5. == Notes == We implemented the couplings to Goldstone bosons so the implementation allows for the use of Feynman gauge. We have checked that the exportation to the `CalcHep` format is successful however we did not check the `CalcHep` output.