MoMEMta - MadGraph Matrix Element Exporter

• Python >= 2.7
• MoMEMta >= 0.1.0 (and its requirements, such as LHAPDF, Boost)
• A C++-11 capable compiler

Note: MoMEMta needs to be installed on the system (locally or globally), cf. MoMEMta documentation.

For the moment, you need a specific version of MadGraph5_aMC@NLO (MG5) for the exporter to work. You can retrieve it here.

Once your copy of MG5 is setup, go the the PLUGIN subfolder. There, download the MoMEMta-MaGMEE plugin (either by cloning the git repository, or by downloading and extracting the archive).

You are now ready to export matrix elements to use in MoMEMta!

Example:

• Go to the MG5 folder
• Launch MG5: bin/mg5_aMC
• Generate your favourite process: generate p p > t t~, (t > w+ b, w+ > e+ ve), (t~ > w- b~, w- > e- ve~)
• Output the process: output MoMEMta myHappyME. myHappyME will be used to define the namespace in which the matrix element code is enclosed, so it has to be a valid C++ variable name.

You now have a folder called myHappyME containing the model's code, a parameter card and the matrix element's code itself.

To build the code and use it in your project, you need to have MoMEMta installed on your system (see the MoMEMta documentation for more details). Then, do:

cd myHappyME
mkdir build
cd build
cmake ..
make -j 4

This generates a shared library that can be dynamically loaded by MoMEMta (using the load_modules() function in the Lua config file).

The following options are available when configuring the the build (when running cmake ..):

• -DMOMEMTA_INCLUDE_DIR=(path): Path to the include directory of your installation of MoMEMta. Use this if your version of MoMEMta was installed locally and not in your system directories
• -DBOOST_ROOT=(path): Use specific Boost version (path to install directory)

The matrix element has a name assigned to it, of type myHappyME_P1_Sigma_pp_ttx_...: this is the name to use when defining the matrix element module in your Lua config file. If you wish to modify it, simply change the name string at the end of the .cc file in the corresponding subfolder of the SubProcesses folder before building the code.