MadGraph5_aMC@NLO

MadGraph5_aMC@NLO [AFF+14] [FFH+18] is a general-purpose event generator that is mainly used to compute observables in double hadronic environments such as the LHC.

Pinecard structure

  • The output.txt file (compulsory). This file contains the instructions to generate the source code for the relevant process. For details, please see [AFF+14] and [FFH+18]. The variable @OUTPUT@ must be used to generate the directory containing the source files.

  • The analysis.f file (compulsory). This Fortran file must fill the histograms from which the HwU files and the PineAPPL grids are generated. Note that a single histogram must not contain more than 100 bins, otherwise MadGraph5_aMC@NLO will crash. However, big histograms can be split up into multiple histograms, for which the runner will merge the PineAPPL grids together.

  • The *.patch file(s) (optional). These are one or more .patch files that are applied after MadGraph5_aMC@NLO has generated the sources.

launch.txt (compulsory)

This file contains the instructions to run the relevant process, including the relevant physical parameters and cuts.

Theory parameters

To insert the actual values of the theory parameters coming from the theorycard we provide a special syntax. You can use the names @GF, @MH@, @MT@, @MW@, @MZ@, @WH@, @WT@, @WW@, and @WZ@, which will be replaced with their numerical values upon generation. The names are the same as chosen by mg5_aMC, but written in uppercase and surrounded with @. For details about more parameters, please see the Template/NLO/Cards/run_card.dat file in MadGraph5_aMC@NLO.

Cuts

They are implemented in two steps:

  1. cuts relevant variables are defined

  2. cuts code is implemented

A list of available codes and variables can be obtained from the repository.

Patches

For instance, to use a dynamical scale, a patch modifying setscales.f file should be included in the directory. To create patches use the command diff -Naurb original new > patch.patch. The patches are applied in an unspecified order, using patch -p1 ....

A list of available patches can be obtained from the repository.

Additional metadata

  • output.txt: contains the generated output.txt script (after all substitutions have been done)

  • launch.txt: contains the generated launch.txt script (after all substitutions have been done)

  • patch: a list of patches’ names, one per row (corresponding to those described in Patches)

  • tau_min: the minimum \(\tau\) value set by the user

  • user_cuts: user defined cuts and cuts values, one per row in the format cut=value (cuts are those defined in Cuts)

  • mg5amc_repo and mg5amc_revno: The repository and revision number of the MadGraph5_aMC@NLO version that was used to generate the grid.

Note

It is guaranteed that the keys listed above are always present in grid’s metadata (even if some of the corresponding values might be empty).

Output

  • DATASET: The directory created by mg5_aMC. A few interesting files in this subdirectory are:

    • Events/-/MADatNLO.HwU: HwU

    • Events/-/amcblast_obs_-.pineappl: grids created by mg5_aMC, not yet merged together

  • output.txt: Run card for the ‘output’ phase, with all variables substituted to their final values

  • output.log: Output of the external runner during the ‘output’ phase

  • launch.txt: Run card for the ‘launch’ phase, with all variables substituted to their final values

  • launch.log: Output of the external runner during the ‘launch’ phase

  • results.log: The numerical results of the run, comparing the results of the grid against the results from mg5_aMC. The first column (PineAPPL) are the interpolated results, which should be similar to the Monte Carlo (MC) results in the second column. The third column gives the relative MC uncertainty (sigma). The next column gives the differences in terms of multiples of sigma. The final three columns give the per mille differences of the central, minimum, and maximum scale varied results. Ideally the first two columns are the same and the remaining columns are zero.