MadGraph5_aMC@NLO

Error Integral Appears to be Zero ( DMsimp Model)

Asked by Chris

Using MG5_aMC_v2_5_2 and a DMsimp_s_spin1 model, I try to generate at NLO:
p p > xd xd~ l+ l-

My jobs terminate with:
 ERROR: INTEGRAL APPEARS TO BE ZERO.
 TRIED 100880 PS POINTS AND ONLY 0 GAVE A NON-ZERO INTEGRAND.

The leptonic coupling to the mediator particle is set to 0. I am interested in generating events that have lepton pairs produced through z/a*.

Thanks

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

If you have some coupling set to zero, the best is to remove them from the model which will allow to not have zero integral.
(The problem is that for the code it is very difficult to know if a zero integral is the result of a integration problem and/or if the amplitude is indeed zero on the full phase-space.

You can look at the follonwing link for an easy way to remove such coupling from your model:
https://answers.launchpad.net/mg5amcnlo/+faq/2312

Cheers,

Olivier

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