Version 11 (modified by richardphysics, 7 months ago) (diff) 

SM + W' and Z' at NLO in QCD
Contact Authors
Benjamin Fuks
 LPTHE  CNRS  UPMC (Paris VI)
 fuks AT lpthe.jussieu.fr
Richard Ruiz
 Universite Catholique de Louvain (CP3)
 richard.ruiz AT uclouvain.be
Model Description
This effective model extends the Standard Model (SM) field content by introducing the massive vector fields W'^{+/} and Z' bosons, which are electrically charged and neutral, respectively. To remain model independent, couplings to SM gauge bosons and scalars are omitted.
Following Refs. [ 1, 2 ], the Lagrangian parameterizing the new vector bosons' couplings to uptype and downtype quark fields u_{i} and d_{j} is given by
Here, i and j denote flavor indices, P_{L/R} are the usual left/righthanded chirality projectors, V^{CKM} is the CKM matrix, and g and \theta_W are the weak coupling constant and mixing angle respectively. We choose coupling normalizations facilitating the mapping to the reference Sequential Standard Model (SSM) Lagrangian {\cal L}_{\rm SSM} [ 3 ]. The realvalued quantities \kappa_{L,R}^q and \zeta_{L,R}^q serve as overall normalization of the new interactions relative to the strength of the weak coupling constant.
The interactions involving charged lepton \ell and massless neutrino \nu_\ell fields are parametrized by
The quantities \kappa_L^\ell are realvalued and serve as normalizations for leptonic coupling strengths. As no righthanded neutrinos are present in the SM, the corresponding righthanded leptonic new physics couplings are omitted (\zeta_R^\nu = \kappa_R^\ell = 0).
From our general Lagrangians, the SSM limit is obtained by imposing the coupling strengths to be equal to the SM weak couplings up to an overall normalization factor:
In the canonical SSM, the overall normalizations are further trivially fixed as
NLO in QCD Corrections
The above Lagrangian in the Feynman Gauge was implemented into FeynRules 2.3.10. QCD renormalization and R2 rational counter terms were determined using NLOCT 1.02 and FeynArts 3.8. Feynman rules were collected into a single UFO, available below. In the UFO file, five massless quarks are assumed as well as vanishing offdiagonal CKM matrix entries. For additional details, see [ 4 ] and references therein. These additions permit treelevel calculations at LO and NLO in QCD, loopinduced calculations at LO in QCD, and NLO calculations matched to NNLL(Veto) resummation using MadGraph_aMC@NLO.
Model Files
 VPrime_NLO_UFO.tgz: Standalone UFO folder.
 vPrimeNLO.fr: Main model file. Relies on sm.fr (default FR model file) being declared elsewhere.
 vPrimeNLO_Notebook.nb: Mathematica notebook file that generates UFO file from FeynRules model files. Allows user to also run quick sanity checks (optional) on model.
 WZPrimeAtNLOfiles.tgz: Standalone package containing vPrimeNLO.fr, vPrimeNLO_Notebook.nb, massless.rst (default FR file), diagonalCKM.rst (default FR file), and sm.fr (default FR file).
 WZPrimeAtNLOfiles_withUFO.tgz: Combination of WZPrimeAtNLOfiles.tgz and VPrime_NLO_UFO.tgz.
Notes
 To download any of the packages and unpack via the terminal, use the commands:
~/Path $ wget http://feynrules.irmp.ucl.ac.be/rawattachment/wiki/WZPrimeAtNLO/VPrime_NLO_UFO.tgz
~/Path $ tar zxvf VPrime_NLO_UFO.tgz
~/Path $ wget http://feynrules.irmp.ucl.ac.be/rawattachment/wiki/WZPrimeAtNLO/WZPrimeAtNLOfiles_withUFO.tgz
~/Path $ tar zxvf WZPrimeAtNLOfiles_withUFO.tgz
 This model contains six free parameters by default:
 Two masses: mzp, mwp, with default values of 3 TeV.
 Two widths: wzp, wwp, with default values of 89.59 and 101.27 GeV, respectively.
 Two coupling normalizations: kL, kR, with default values 1.0 and 0.0, respectively.
Validation
 The model file was validated at NLO in [ 4 ] by comparing against Standard Model predictions and W^{'} predictions from [ 5 ], as well as private LO and NLO calculations. See Table III of [ 4 ] for representative total widths that have been checked against analytic computation.
List of studies that have used the model file
 Please email to update this space.
References
 Please cite [3,4] for the model file, [4,5] for NLO corrections, and [6] for automated veto resummation.
[1] S. Gopalakrishna, T. Han, I. Lewis, Z.G. Si and Y. F. Zhou, Chiral Couplings of W' and Top Quark Polarization at the LHC, PRD82, 115020 (2010) arXiv:1008.3508 [hepph]
[2] T. Han, I. Lewis, R. Ruiz and Z.G. Si, Lepton Number Violation and W' Chiral Couplings at the LHC, PRD87, no. 3, 035011 (2013) arXiv:1211.6447 [hepph]
[3] G. Altarelli, B. Mele and M. RuizAltaba, Searching for New Heavy Vector Bosons in p \bar{p} Colliders, Z. Phys. C45, 109 (1989), doi:10.1007/BF01556677
[4] B. Fuks, R. Ruiz, A Comprehensive Framework for Studying W' and Z' Bosons at Hadron Colliders with Automated Jet Veto Resummation, arXiv:1701.05263 [hepph]
[5] Z. Sullivan, Fully differential W' production and decay at nexttoleading order in QCD, PRD66, 075011 (2002), arXiv:hepph/0207290
[6] T. Becher, R. Frederix, M. Neubert and L. Rothen, Automated NNLL + NLO resummation for jetveto cross sections, EPJC75, no. 4, 154 (2015) arXiv:1412.8408 [hepph]
Attachments (5)

vPrimeNLO.fr
(7.3 KB) 
added by richardphysics 3 years ago.
W' Z' FeynRules model file in Feynman gauge

vPrimeNLO_Notebook.nb
(16.1 KB) 
added by richardphysics 3 years ago.
W' Z' NLO FR mathematica notebook that loads model file, performs basic sanity checks, and outputs to desired format, e.g., UFO.

VPrime_NLO_UFO.tgz
(21.3 KB) 
added by richardphysics 3 years ago.
Standalone NLO UFO model file: assumes top quark is the only massive fermion + diagonal CKM

WZPrimeAtNLOfiles.tgz
(11.9 KB) 
added by richardphysics 3 years ago.
Standalone package containing vPrimeNLO.fr, vPrimeNLO_Notebook.nb, massless.rst (default FR file), diagonalCKM.rst (default FR file), and sm.fr (default FR file).

WZPrimeAtNLOfiles_withUFO.tgz
(46.7 KB) 
added by richardphysics 3 years ago.
Combination of WZPrimeAtNLOfiles.tgz and VPrime_NLO_UFO.tgz
Download all attachments as: .zip