Changes between Version 20 and Version 21 of SMEFTatNLO


Ignore:
Timestamp:
Nov 10, 2020, 5:13:00 PM (4 years ago)
Author:
gdurieux
Comment:

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  • SMEFTatNLO

    v20 v21  
    111111The corresponding Goldstone boson interactions are not included, such that the extended model can only be used in unitary gauge (default).
    112112
     113==== !MadSpin
     114[https://cp3.irmp.ucl.ac.be/projects/madgraph/wiki/MadSpin MadSpin] can be used to perform tree-level decays (accounting for leading-order spin correlations).
     115Information about the branching fractions of the decayed particles should then be included in the restriction (and/or param) card used.
     116E.g. for the top quark, Z and W bosons:
     117{{{
     118DECAY  6   1.470800e+00
     119   1.000000e+00   2    5  24 # 1.4708
     120DECAY  23   2.416039e+00
     121   1.517939e-01   2    -1  1
     122   1.517939e-01   2    -3  3
     123   1.517939e-01   2    -5  5
     124   1.176099e-01   2    -2  2
     125   1.176099e-01   2    -4  4
     126   6.865783e-02   2    -12  12
     127   6.865783e-02   2    -14  14
     128   6.865783e-02   2    -16  16
     129   3.447502e-02   2    -11  11
     130   3.447502e-02   2    -13  13
     131   3.447502e-02   2    -15  15
     132DECAY  24   2.002950e+00
     133   3.333333e-01   2    -1  2
     134   3.333333e-01   2    -3  4
     135   1.111111e-01   2    -11  12
     136   1.111111e-01   2    -13  14
     137   1.111111e-01   2    -15  16
     138}}}
     139These values can be recomputed for a given param_card by running {{{compute_widths <particle-name> --path=<input-param-card> --output=<updated-param-card>}}} after having loaded the model.
     140To ensure gauge invariance, MadGraph_aMC@NLO would still set the widths of external particles to zero (saying, e.g., "For gauge cancellation, the width of 'Z' has been set to zero") but pass the required information to !MadSpin.
     141If the EFT coefficient varied affect the widths of the decayed particles, extra care must be taken to properly account for that dependence.
     142
    113143=== Generation recipes for validated processes ===
    114144Among many others, the following processes are supported at the one-loop level.
    115145Gauge invariance (see {{{help check}}} in MadGraph5_aMC@NLO) and pole cancellation have been checked explicitly for those.
     146Widths should be set to zero to ensure gauge invariance.
    116147For complicated processes and in case of doubts, please contact the authors.
    117 Widths should be set to zero to ensure gauge invariance.
    118148
    119149==== QCD ====