= '''Standard Model Effective Field Theory -- The SMEFTsim package''' =
== Authors ==
Ilaria Brivio, Yun Jiang and Michael Trott
{{{
ilaria.brivio@nbi.ku.dk, yunjiang@nbi.ku.dk, michael.trott@cern.ch
}}}
''NBIA and Discovery Center, Niels Bohr Institute, University of Copenhagen''
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== The model description ==
The Standard Model Effective Field Theory (SMEFT) is constructed out of a series of SU(3),,C,, × SU(2),,L,, × U(1),,Y,, invariant higher dimensional operators L^(6)^, L^(7)^, ... built out of the SM fields.[[BR]]
The SMEFTsim package provides a complete implementation of the lepton and baryon number conserving dimension-6 Lagrangian adopting the Warsaw basis [https://arxiv.org/abs/1008.4884/ arXiv:1008.4884][[BR]]
The [http://feynrules.irmp.ucl.ac.be/wiki/StandardModel/ SM Lagrangian] is included and extended with the SM loop-induced Higgs couplings to gg, γγ and Zγ. [[BR]]
The SMEFTsim package provides implementations for 3 different flavor symmetry assumptions and 2 input scheme choices.
The flavor symmetry assumptions adopted are (see [https://arxiv.org/abs/1709.06492/ arXiv:1709.06492] for a detailed description)
* The flavour general case
* The U(3)^5^ flavor symmetric case, with non-SM CP-violating phases
* A linear Minimal flavor violation (MFV) ansatz [https://arxiv.org/abs/hep-ph/0207036/ arXiv:0207036], in which non-SM CP-violating effects are neglected, but linear flavor-violating spurion insertions are allowed in quark currents
For each model it is free to choose between two input parameters sets for the electroweak sector, namely:
* α scheme: {α,,ew,,, m,,Z,, , G,,f,,}
* m,,W,, scheme: {m,,W,,, m,,Z,, , G,,f,,}
Importantly, field rotations required to have canonically normalized kinetic terms and parameter redefinitions following from the choice of an input parameters set are automatically applied in the Lagrangian.
Two independent models sets (A and B) are supplied. Each set contains a main file, a number of subroutines and restriction files.
The two sets differ in the structure and in the technical implementation of L^(6)^, but they produce consistent results. The use of both sets is recommended for debugging and validation of the numerical results.[[BR]]
Pre-exported UFO files to be interfaced with MadGraph5_aMC@NLO can also be downloaded from this page (see Table below).
We would appreciate if you could report to us any inconsistency or bugs.
'''Usage recommendations'''
The SMEFTsim package is designed to enable numerical studies of the LO interference of the SMEFT with the SM, while neglecting NLO corrections.
In this spirit, it has not been optimized for loop calculations in the SM or in the SMEFT. In particular:
* the Lagrangian assumes unitary gauge. Using it in R,,ξ,, or Feynman gauge may lead to inconsistent results, as the ghost Lagrangian has not been modified to account for L^(6)^ corrections.
* the UFO files are not equipped for NLO evaluation in MadGraph5_aMC@NLO
Numerical files in the WCxf format (https://wcxf.github.io) can be translated into a param_card for SMEFTsim using the dedicated command-line script now available in the WCxf package.
'''Related bugs and threads'''
The most recent version of SMEFTsim requires MadGraph5_aMC@NLO v2.6.1. [[BR]]
If still experiencing errors, please refer to the following threads or contact us.
https://bugs.launchpad.net/mg5amcnlo/+bug/1732756 [[BR]]
https://answers.launchpad.net/mg5amcnlo/+question/657094 [[BR]]
https://bugs.launchpad.net/mg5amcnlo/+bug/1813280
== Change log ==
'' Note that the version number adopted in two model Sets is independent.''
set A - v2.1 (14.12.2018)
- all the restriction cards have been modified to include the tau lepton mass (also in the massless limit) and replacing the values 0 and 1 respectively with 1e-99 and 9.999999e-01. [[BR]]
This prevents the parameters restricted to 0 or 1 from disappearing in the param_card of generated processes, allowing to modify their value at a later stage.
set A - v2.1 (20.03.2018)
- restriction files added to MFV and U(3)^5^ UFOs
set A - v2.1 (13.03.2018)
- a mistake in the dependence of dGf on c,,ll,,, c,,ll,,' has been corrected in the U(3)^5^ an MFV models. [[BR]] [[BR]]
The correct expression is δG,,F,, = G,,F,, ( c,,Hl,,^(3)^ − C,,ll,,' / 2 ) (Eq. (3.3) in the [https://arxiv.org/pdf/1709.06492.pdf paper] should be modified accordingly)
set A - v2.0 (07.02.2018)
- fixed bug with complex Wilson coefficient
- Wilson coefficient of the operator O_HD renamed: cHD > cHDD to avoid conflict with cHd
- SM radiative couplings of the Higgs (hgg, haa, haz) assigned the corresponding QCD, QED orders, plus a dedicated SMHLOOP=1 interaction order.
- idle parameter ceeAbs2332 removed in the flavor general models
- further restrictions for top physics added to the flavor general, alpha scheme UFO.
Set B - v1.3 (06.02.2018)
- The cutoff scale Lambda has been introduced explicitly and assigned the proper InteractionOrder with the corresponding change made for Gf and vev parameters.
- Typo in the definition of dlam is corrected.
- Minor bugs with the color structure constant appearing in the Q,,G,, and Q,,Gtilde,, operators fixed.
v1.2 (24.11.2017)
- set A: LSMshifted renamed into LSMlinear for consistency with set B
v1.1 (20.10.2017)
- restriction cards topEFT added to each UFO and to the FeynRules source. They assume massless light fermions and set to 0 coefficients that are not relevant for top quark physics.
- set A: bug with operators Q,,Hu,,, Q,,Hd,,, Q,,Hud,,, Q,,Hq,,^1^, Q,,Hq,,^3^ in the MFV UFO files fixed.
- set B: bug with operators Q,,Hq,,^(1)^ in FLU model and bugs with operators Q,,Hu,,, Q,,Hd,,, Q,,Hq,,^(1)^, Q,,Hq,,^(3)^, Q,,Hl,,^(1)^ in MFV UFO files fixed.
v1.0 (19.09.2017)
- The first version released
== References ==
* I. Brivio, Y. Jiang and M. Trott, ''The SMEFTsim package, theory and tools'', JHEP **1712** (2017) 070 [https://arxiv.org/abs/1709.06492/ arXiv:1709.06492]
* J. Aebischer, I. Brivio, A. Celis, J. Evans, Y. Jiang, J. Kumar, X. Pan, W. Porod, J. Rosiek, D. Shih, F. Staub, D. Straub, D. Dyk, A. Vicente, ''WCxf: an exchange format for Wilson coefficients beyond the Standard Model'', arXiv:1712.05298
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'''Model Set A'''
* [attachment:"SMEFTsim-setA-v2.1.tar.gz"] This archive contains all the FeynRules files.
* [attachment:"SMEFTsim-setA.nb"] Example of a Mathematica® notebook loading the model
'''Model Set B''
In the master code two flags are established: __Scheme__ and __Flavor__, which are used to identify the input scheme and flavor assumption being adopted in loading the model.
* [attachment:"SMEFTsim-setB_v13.zip"] This archive contains all the model files. Should be expanded in the FR model directory.
* [attachment:"SMEFTsim-setB_v13.nb"] Example of a Mathematica® notebook loading the model. Should be stored in the SMEFTsim-setB model folder.
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== Pre-exported UFO files (include restriction cards) ==
|| || Set A || || Set B (v 1.3)|| ||
|| || α scheme || m,,W,, scheme || α scheme || m,,W,, scheme ||
|| Flavor general SMEFT || [attachment:"SMEFTsim_A_general_alphaScheme_UFO_v2.tar.gz"] || [attachment:"SMEFTsim_A_general_MwScheme_UFO_v2.tar.gz"] || [attachment:"SMEFT_alpha_UFO.zip"] || [attachment:"SMEFT_mW_UFO.zip"] ||
|| MFV SMEFT || [attachment:"SMEFTsim_A_MFV_alphaScheme_UFO_v2.1.tar.gz"] || [attachment:"SMEFTsim_A_MFV_MwScheme_UFO_v2.1.tar.gz"] || [attachment:"SMEFT_alpha_MFV_UFO.zip"] || [attachment:"SMEFT_mW_MFV_UFO.zip"] ||
|| U(3)^5^ SMEFT || [attachment:"SMEFTsim_A_U35_alphaScheme_UFO_v2.1.tar.gz"] || [attachment:"SMEFTsim_A_U35_MwScheme_UFO_v2.1.tar.gz"] || [attachment:"SMEFT_alpha_FLU_UFO.zip"] || [attachment:"SMEFT_mW_FLU_UFO.zip"] ||