MadGraph5_aMC@NLO

Wrong number of weights

Asked by Amin Aboubrahim

Hi Olivier,

Using Pythia8 inside MG5 2.6.0, I have obtained a hepmc file in which matching/merging has been switched on along with the systematics. Because of that, weights were added to the file rather than vetoing events. When I tried running Delphes on this file, it failed in reading it. It turns out that the error is coming from this line:

E 0 -1 -1.0000000000000000e+00 -1.0000000000000000e+00 -1.0000000000000000e+00 0 0 94 1 2 0 7 3.1671032000000003e-05 3.1671032000000003e-05 3.1671032000000003e-05 3.0000000000000000e+01 4.1375492312388307e+00 1.0000000000000000e+10

The number of weights is set to 7 but only 6 are generated. The Delphes team said it is caused by the code producing the file.
Is this an MG5 or pythia8 issue?

Thank you,
Amin

Question information

Language:
English Edit question
Status:
Needs information
For:
MadGraph5_aMC@NLO Edit question
Assignee:
Stefan Prestel Edit question
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Revision history for this message
Amin Aboubrahim (amin83) said : 		#1

Hi,

Does anyone have an idea what could be the problem in this?

Thank you in advance,
Amin

Revision history for this message
Valentin Hirschi (valentin-hirschi) said : 		#2

You can try to turn off systematics (use_syst set to False in the run_card) and I believe that the hepmc file produced should then contain a single weight only.
But if you could specify exactly the step to reproduce your issue (process definition and all Cards) then Stefan P. may be able to understand this apparent bug (it is the MG5_Pythia8 interface tool that effectively produces the hepmc).

Can you help with this problem?

Provide an answer of your own, or ask Amin Aboubrahim for more information if necessary.

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