MadGraph5_aMC@NLO

interface with gosam

Asked by Wei-Hua Lee

 Dear MG-Team,

    I want to use the Madgraph5_aMC calculating the one-loop EW correction, but I do not know how to inteface with gosam which
can calculate the virtual part with the BLHA1/2.

    Would you please suggest me how to resolve this.
   Thank you!

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
Valentin Hirschi Edit question
Solved by:
Valentin Hirschi
Solved:
Last query:
Last reply:
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Best Valentin Hirschi (valentin-hirschi) said : 		#1

Dear Wei-Hua Lee,

For QCD corrections on SM processes, you can type

'set OLP GoSam'

in MG5_aMC interface to switch to using GoSam for the generation of the virtual (making sure you have gosam.py available in your path).
Notice however, that MG5_aMC cannot compute QED/EW corrections yet and this interface is working for QCD corrections only.
In the current development version, MadLoop can already handle QCD/QED/EW mixed corrections to any SM process but some more work needs to be done on the aMC@NLO integration end.
If you are only interested in finite pure EW corrections, the easiest way to proceed would be to interface by hand the GoSam code for the EW loop matrix elements to a MadEvent (i.e. leading order) output (typically by substituting the subroutine 'smatrix' in the files 'matrix<I>.f'

I hope this helps,

Revision history for this message
Wei-Hua Lee (lwh1987) said : 		#2

Thanks Valentin Hirschi, that solved my question.