MadGraph5_aMC@NLO

Force Madgraph not to combine sub processes

Asked by Silvan Kuttimalai

Hello,

I would like to generate c++ standalone output for a large number of SUSY processes in order to extract matrix elements for sets of phase space points. It would help me a lot if the c++ output was organized such that there is one subdirectory for each sub process in the "SubProcesses" directory. Since Madgraph automatically combines certain processes (in particular u u~ > cl cl~ and d d~ > cl cl~ for example), this is not what happens if i use a process card like this one:

import model mssm
add process u u~ > cl cl~
add process d d~ > cl cl~
output standalone_cpp

Is there a way to prevent Madgraph from combining ANY processes?
Thanks a lot!

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi Silvan,

In fact they are no real sense to have two directories for
u u~ > cl cl~ and d d~ > cl cl~
since the matrix element is exactly the same. So if you really want to directory you can do a simple 'cp'.

Not sure if that change anything on the c++ standalone output, but I would advise you to use the following command:
set group_subprocesses False
which ensures that only 100% identical matrix element are merged. This will also prevent the merging of
u u~ > cl cl~ and of u~ u > cl cl~.

Cheers,

Olivier

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