Changes between Version 9 and Version 10 of dim6top
 Timestamp:
 10/14/19 10:48:39 (11 months ago)
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dim6top
v9 v10 46 46  20180528: moved the definition of 'ctA' below that of 'sw' and 'cw' in parameters.py, to avoid "MadGraph5Error : Unable to evaluate mdl_ctA = (mdl_ctWmdl_cw*mdl_ctZ)/mdl_sw: raise error: name 'mdl_cw' is not defined" (thanks to Marcel Vos) 47 47  20180521: corrected the Lorentz structure of Oledq operator from tensor to scalar (thanks to Ken Mimasu) 48 49 ==== Note on NLO QCD 50 For NLO QCD simulation, the model authors recommend using the [wiki:SMEFTatNLO SMEFT@NLO] model which is mostly compatible with the baseline prescription of the LHC TOP WG. Few differences between the {{{dim6top}}} and [wiki:SMEFTatNLO SMEFT@NLO] (August 2019 version) models are to be noted: 51  [wiki:SMEFTatNLO SMEFT@NLO] includes Higgs and electroweak operators but does not include topquark FCNCs. 52  [wiki:SMEFTatNLO SMEFT@NLO] is moreover restricted to CPconserving operator coefficients. 53  [wiki:SMEFTatNLO SMEFT@NLO] imposes an enhanced U(2)q×U(2)u×U(3)d flavour symmetry in the quark sector, such that the righthanded bottom quark is treated on the same footing as other light downtype quarks. This is required for consistency with the fiveflavour scheme at NLO QCD, where {{{MB=0}}}. 54  [wiki:SMEFTatNLO SMEFT@NLO] normalizes the top dipole operator (with coefficient {{{ctG}}}) with a factor of the strong coupling constant {{{G}}} for compatibility with MG 2.x series at NLO in QCD. The 3.x series does not requires it. This implies that {{{ctG_dim6top = G * ctG_SMEFTatNLO}}}. Note that {{{G}}} runs. 55 56 Altogether, due to the enhanced quark flavour symmetry and to CPconservation, [SMEFTatNLO] only includes a subset of 45 topquark operator coefficients: 57 cQQ1, cQQ8, cQd1, cQd8, cQe1, cQe2, cQe3, cQl31, cQl32, cQl33, cQlM1, cQlM2, cQlM3, cQq11, cQq13, cQq81, cQq83, cQt1, cQt8, cQu1, cQu8, cblS3, cdp, cpQ3, cpQM, cpt, ctG, ctW, ctZ, ctd1, ctd8, cte1, cte2, cte3, ctl1, ctl2, ctl3, ctlS3, ctlT3, ctp, ctq1, ctq8, ctt1, ctu1, ctu8 58 and equates cQb1=cQd1, cQb8=cQd8, ctb1=ctd1, ctb8=ctd8. 59 60 A highprecision comparison with {{{dim6top}}} has been performed at leading order following the prescription of [https://arxiv.org/abs/1906.12310 1906.12310], with the [https://bazaar.launchpad.net/~rwgtdim6/mg5amcnlo/plugin_eft_contrib/revision/ plugin_eft_contrib] of MG. 61 62 The [wiki:SMEFTatNLO SMEFT@NLO] version dated from August 2019 does not include an implementation of fourfermion operators at NLO in QCD. Its validation is ongoing.