W' Effective model
Authors
 Benjamin Fuks
 CERN / IPHC Strasbourg / University of Strasbourg
 fuks@…
 Julien Donini
 LPC Clermont / University of ClermontFerrand
 julien.donini@… (cern.ch)
Description of the model
This model is an extension of the SM, including additional interaction of fermions to a W' boson following the lowestorder effective Lagrangian described in Refs. [1] [2]:
where g'_{R,L} are the righthanded (lefthanded) W'boson gauge couplings to fermions f_{i} and f_{j}, and V'_{ij} is either the CKM matrix or a diagonal matrix, for quarks and leptons respectively.
Model files
 weff.fr: the main model file.
 WEff.nb: example of Mathematica notebook that loads the model, calculates the Feynman rules and extract the model files within the UFO format.
 weff.ufo.tgz: The model files in UFO format (for MadGraph 5).
Notes:
 The W'boson mass and width are set using the parameters MWp and WWp, respectively
 The lefthanded (righthanded) W'boson couplings to quarks and leptons are given by the matrices CLq and CLl (CRq and CRl) respectively.
By default CLq and CRq are set to the CKM values and CLl and CRl are set to identity.  The lefthanded and righthanded W'boson coupling constants are set by the parameters gL and gR.
By default these values are set at 0.1.
Validation
The W' model was validated using MadGraph in the context of W' > tb searches at the LHC [3]:
 Several kinematical distributions of the W' decay products (including from topquark decay) were checked, at the parton level or after showering (using Pythia).
Variables sensitive to the W' chirality were studied (such as cos(theta*): the angle between the lepton in the topquark rest frame and the top direction in the CM frame).
 The crosssections calculated with this model were compared to theoretical values from [2]. Results for left and righthanded W' were shown
to be in very good agreement with LO calculations over all tested mass range (0.5 to 3.0 TeV).
References
[1] Z. Sullivan, Fully differential W production and decay at nexttoleading order in QCD, Phys. Rev. (2002) 075011, arXiv:hepph/0207290 [hepph].
[2] D. Duffty and Z. Sullivan, Model independent reach for Wprime bosons at the LHC, Phys. Rev. D86 (2012) 075018, arXiv:1208.4858 [hepph].
[3] ATLAS Collaboration, Search for W′→ tb in protonproton collisions at a centreofmass energy of √s = 8 TeV with the ATLAS detector (2013), ATLASCONF2013050
Attachments

WEff.nb
(3.7 KB) 
added by donini 5 years ago.
this is an example Mathematica notebook that loads the model, calculates the Feynman rules and extract the model files within the UFO format.

weff.fr
(4.4 KB) 
added by BenjF 4 weeks ago.
the main model file.
 weff.ufo.tgz (195.5 KB)  added by BenjF 4 weeks ago.