Changes between Version 10 and Version 11 of dim6top
- Timestamp:
- Oct 14, 2019, 10:55:40 AM (5 years ago)
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dim6top
v10 v11 48 48 49 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: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 [wiki:dim6top dim6top] and [wiki:SMEFTatNLO SMEFT@NLO] (August 2019 version) models are to be noted: 51 51 - [wiki:SMEFTatNLO SMEFT@NLO] includes Higgs and electroweak operators but does not include top-quark FCNCs. 52 52 - [wiki:SMEFTatNLO SMEFT@NLO] is moreover restricted to CP-conserving operator coefficients. 53 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 right-handed bottom quark is treated on the same footing as other light down-type quarks. This is required for consistency with the five-flavour 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 require sit. This implies that {{{ctG_dim6top = G * ctG_SMEFTatNLO}}}. Note that {{{G}}} runs.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 require it. This implies that {{{ctG_dim6top = G * ctG_SMEFTatNLO}}}. Note that {{{G}}} runs. 55 55 56 Altogether, due to the enhanced quark flavour symmetry and to CP-conservation, [ SMEFTatNLO] only includes a subset of 45 top-quark operator coefficients:56 Altogether, due to the enhanced quark flavour symmetry and to CP-conservation, [wiki:SMEFTatNLO SMEFT@NLO] only includes a subset of 45 top-quark operator coefficients: 57 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 58 and equates cQb1=cQd1, cQb8=cQd8, ctb1=ctd1, ctb8=ctd8. 59 59 60 A high-precision 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.60 A high-precision comparison with [wiki:dim6top 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. More details are found in the arxiv note and in the {{{example}}} directory of the plugin. 61 61 62 62 The [wiki:SMEFTatNLO SMEFT@NLO] version dated from August 2019 does not include an implementation of four-fermion operators at NLO in QCD. Its validation is ongoing.