MadGraph5_aMC@NLO

discrepancy in cross-section calculation

Asked by Jayita

Hi,

  I have been trying to calculate cross-section of a simple process p p > h2 h2 l+ l- in Madgraph, using the available InertDoublet UFO available on feynrules database. On running the same param_card twice I get the cross-section 0.008208+/-2.08e-05 pb and then 0.008469 +/- 1.876e-05 pb. The difference in the central values is almost 3%, while the error bar predicts 0.2% difference. Is there a way to understand such a large discrepancy? I am using Madgraph 3.1.0.

Thank you,

Best regards,
Jayita

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
Last query:
Last reply:
Revision history for this message
Best Olivier Mattelaer (olivier-mattelaer) said : 		#1

Given that 3.1.0 is quite old and that we did have fix bug that could explain such behavior (in the handling of the helicity). I would suggest to move to more recent version of the code and retry.
If that does not fix your issue, I can take a look but I would then need to have the exact name of the model
as well as the param_card and run_card such that I can reproduce such missmatch.

Cheers,

Olivier

Revision history for this message
Jayita (jlahiri29) said : 		#2

Thanks Olivier Mattelaer, that solved my question.