Changes between Version 4 and Version 5 of dim6top


Ignore:
Timestamp:
02/21/18 12:05:04 (18 months ago)
Author:
gdurieux
Comment:

Reference to arxiv added.

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  • dim6top

    v4 v5  
    11= A complete top-quark EFT implementation
    22
    3 Under the umbrella of the LHC TOP WG, common standards and prescriptions were established for the EFT interpretation of top-quark 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.
     3Under the umbrella of the LHC TOP WG, common standards and prescriptions were established for the EFT interpretation of top-quark 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.
    44
    5 EFT degrees of freedom that are natural for the description of top-quark 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 top-quark couplings to physical W and Z gauge bosons.
     5EFT degrees of freedom that are natural for the description of top-quark 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 top-quark couplings to physical W and Z gauge bosons (see Appendices C, D, and E of the note for degrees of freedom definitions).
    66
    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 (four-quark, two-quark, and two-quark-two-lepton operators). Baryon and lepton number violating operators are not included. In total the model includes O(90) flavour-conserving degrees of freedom which have a {{{DIM6=1}}} coupling order.
     7The 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 (four-quark, two-quark, and two-quark-two-lepton operators). Baryon and lepton number violating operators are not included. In total the model includes O(90) flavour-conserving degrees of freedom which have a {{{DIM6=1}}} coupling order.
    88
    99Enhancing 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 ''top-philic'' can also be obtained following the constraints given in the note.
     
    1111Top-quark 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.
    1212
    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:
     13Two 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:
    1414{{{
    1515> generate p p > t t~ FCNC=0 DIM6^2==1 DIM6_ctZ^2==1
    1616> generate p p > t t~ FCNC=0 DIM6^2==2 DIM6_ctZ^2==1 DIM6_ctW^2==1
    1717}}}
     18would for instance respectively retain only the interference between SM and {{{ctZ}}} amplitudes, and
     19the interferences between {{{ctZ}}} and {{{ctW}}} amplitudes, in top pair production.
    1820
    1921Only tree-level simulation in the unitary gauge is possible. Loop induced couplings of the Higgs boson to pairs of gluons, photons, or {{{Zγ}}} are not included.
     
    2628> define j = p
    2729}}}
    28 before process generation and setting {{{MB}}} to {{{0}}} in the {{{param_card}}}.
     30before process generation and setting {{{MB}}} to {{{0}}} in the {{{param_card}}} (setting {{{ymb}}} to {{{0}}} may also be desired, for consistency).
    2931
    30 Benchmark results for the linear and quadratic dimension-six EFT dependences of total rates are provided in Tables 10-21 of the note, for processes like {{{ pp→tt̅, tt̅bb̅, tt̅tt̅, tt̅e⁺ν, tt̅e⁺e⁻, tt̅γ, tt̅h }}} and {{{ pp→tj, te⁻ν̅, tje⁺e⁻, tjγ, tjh}}}.
     32Benchmark results for the linear and quadratic dimension-six EFT dependences of total rates are provided in Tables 10-21 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}}}.
    3133
    32 Please refer to [https://arxiv.org/abs/1802.xxxxx] for further details and when using this model.
     34Please refer to [https://arxiv.org/abs/1802.07237] for further details and when using this model.
    3335
    3436Contact persons are Gauthier Durieux and Cen Zhang.
     
    3638Feynrule files: [attachment:dim6top.m], [attachment:dim6top.fr], [attachment:dim6top_each_coupling_order.fr]
    3739
    38 Model files: [attachment:dim6top_LO_UFO.tar.gz], [attachment:dim6top_LO_UFO_each_coupling_order.tar.gz]
     40UFO model files: [attachment:dim6top_LO_UFO.tar.gz], [attachment:dim6top_LO_UFO_each_coupling_order.tar.gz]