Changes between Version 4 and Version 5 of dim6top
 Timestamp:
 02/21/18 12:05:04 (18 months ago)
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dim6top
v4 v5 1 1 = A complete topquark EFT implementation 2 2 3 Under the umbrella of the LHC TOP WG, common standards and prescriptions were established for the EFT interpretation of topquark measurements at the LHC. They are summarized in the note at [https://arxiv.org/abs/1802. xxxxx]. Details concerning the present UFO model implementation are provided in Appendix B.1.3 Under the umbrella of the LHC TOP WG, common standards and prescriptions were established for the EFT interpretation of topquark measurements at the LHC. They are summarized in the note at [https://arxiv.org/abs/1802.07237]. Details concerning the present UFO model implementation are provided in Appendix B.1. 4 4 5 EFT degrees of freedom that are natural for the description of topquark processes were defined as linear combinations of Warsaw basis operator coefficients. They match the interference structure of the EFT with SM amplitudes and give a direct parametrization of the topquark couplings to physical W and Z gauge bosons .5 EFT degrees of freedom that are natural for the description of topquark processes were defined as linear combinations of Warsaw basis operator coefficients. They match the interference structure of the EFT with SM amplitudes and give a direct parametrization of the topquark couplings to physical W and Z gauge bosons (see Appendices C, D, and E of the note for degrees of freedom definitions). 6 6 7 The CKM matrix is approximated as a unit matrix. Masses and Yukawa couplings of all fermions except for the top and bottom quarks are neglected by default. A U(2)q+u+d flavour symmetry is imposed on the first two generations of quarks . All operators of the Warsaw basis involving a top quark and satisfying this flavour assumption are included (fourquark, twoquark, and twoquarktwolepton operators). Baryon and lepton number violating operators are not included. In total the model includes O(90) flavourconserving degrees of freedom which have a {{{DIM6=1}}} coupling order.7 The CKM matrix is approximated as a unit matrix. Masses and Yukawa couplings of all fermions except for the top and bottom quarks are neglected by default. A U(2)q+u+d flavour symmetry is imposed on the first two generations of quarks (see Section 4 of the note for details). All operators of the Warsaw basis involving a top quark and satisfying this flavour assumption are included (fourquark, twoquark, and twoquarktwolepton operators). Baryon and lepton number violating operators are not included. In total the model includes O(90) flavourconserving degrees of freedom which have a {{{DIM6=1}}} coupling order. 8 8 9 9 Enhancing the U(2)q+u+d flavour symmetry to U(2)q×U(2)u×U(2)d (the baseline scenario considered as prescription) is done by neglecting the 10+10 CPV supplementary degrees of freedom. A further restriction to the ''topphilic'' can also be obtained following the constraints given in the note. … … 11 11 Topquark FCNCs are also included by allowing one quark bilinear in each operator to break the U(2)q×U(2)u×U(2)d baseline flavour symmetry requirement and couple the third generation with either the first or the second. Operators with one light and one heavy quark, one light quark one heavy quark and two leptons, one light quark and three heavy quarks, three light and one heavy quark are included. The O(300) degrees of freedom are assigned a {{{FCNC=1}}} coupling order. Requiring {{{FCNC=0}}} at the generation level is required to not consider them. 12 12 13 Two versions of the models are provided {{{dim6top_LO_UFO}}} and {{{dim6top_LO_UFO_each_coupling_order}}}. In the second one, each degree of freedom is assigned with an individual coupling order, like {{{DIM6_ctZ}}}, {{{DIM6_cQQ1}}}, or {{{FCNC_cqq11x3331}}}. This allows for the selection of individual degrees of freedom interferences at the generation level in {{{MG5_aMC@NLO}}} , using the syntax:13 Two versions of the models are provided {{{dim6top_LO_UFO}}} and {{{dim6top_LO_UFO_each_coupling_order}}}. In the second one, each degree of freedom is assigned with an individual coupling order, like {{{DIM6_ctZ}}}, {{{DIM6_cQQ1}}}, or {{{FCNC_cqq11x3331}}}. This allows for the selection of individual degrees of freedom interferences at the generation level in {{{MG5_aMC@NLO}}}. The syntax: 14 14 {{{ 15 15 > generate p p > t t~ FCNC=0 DIM6^2==1 DIM6_ctZ^2==1 16 16 > generate p p > t t~ FCNC=0 DIM6^2==2 DIM6_ctZ^2==1 DIM6_ctW^2==1 17 17 }}} 18 would for instance respectively retain only the interference between SM and {{{ctZ}}} amplitudes, and 19 the interferences between {{{ctZ}}} and {{{ctW}}} amplitudes, in top pair production. 18 20 19 21 Only treelevel simulation in the unitary gauge is possible. Loop induced couplings of the Higgs boson to pairs of gluons, photons, or {{{Zγ}}} are not included. … … 26 28 > define j = p 27 29 }}} 28 before process generation and setting {{{MB}}} to {{{0}}} in the {{{param_card}}} .30 before process generation and setting {{{MB}}} to {{{0}}} in the {{{param_card}}} (setting {{{ymb}}} to {{{0}}} may also be desired, for consistency). 29 31 30 Benchmark results for the linear and quadratic dimensionsix EFT dependences of total rates are provided in Tables 1021 of the note, for processes like {{{ pp→tt̅, tt̅bb̅, tt̅tt̅, tt̅e⁺ν, tt̅e⁺e⁻, tt̅γ, tt̅h }}} and {{{ pp→tj, te⁻ν ̅, tje⁺e⁻, tjγ, tjh}}}.32 Benchmark results for the linear and quadratic dimensionsix EFT dependences of total rates are provided in Tables 1021 of the note, for processes like {{{ pp→tt̅, tt̅bb̅, tt̅tt̅, tt̅e⁺ν, tt̅e⁺e⁻, tt̅γ, tt̅h }}} and {{{ pp→tj, te⁻ν, tje⁺e⁻, tjγ, tjh}}}. 31 33 32 Please refer to [https://arxiv.org/abs/1802. xxxxx] for further details and when using this model.34 Please refer to [https://arxiv.org/abs/1802.07237] for further details and when using this model. 33 35 34 36 Contact persons are Gauthier Durieux and Cen Zhang. … … 36 38 Feynrule files: [attachment:dim6top.m], [attachment:dim6top.fr], [attachment:dim6top_each_coupling_order.fr] 37 39 38 Model files: [attachment:dim6top_LO_UFO.tar.gz], [attachment:dim6top_LO_UFO_each_coupling_order.tar.gz]40 UFO model files: [attachment:dim6top_LO_UFO.tar.gz], [attachment:dim6top_LO_UFO_each_coupling_order.tar.gz]