MadGraph5_aMC@NLO

NLO syntax in MadGraph

Asked by Marzieh Bahmani

Hi,

I want to generate NLO sample with MadGraph, here is the commands:

import model SM_HeavyN_Meson_NLO

generate pp > l n1, n1 > l pi [QCD]

I get this error : ERROR str : Decay processes cannot be perturbed

I am using v 3.3.1. I was wondering whether the syntax is not correct or I should use different version.
I can not use madspin for decay process, there is a problem with the model.

thanks ,

Marzieh

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Rewas (rewas12) said : 		#1

Rewas suggests this article as an answer to your question: Facing the same issue https://fikfapapk.net/
FAQ #3399: “The effect of the flag nlo_mixed_expansion”.

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Olivier Mattelaer (olivier-mattelaer) said : 		#2

Hi,

Please ignore the spam bot above.

We do not support [QCD] syntax in a conjunction with the decay syntax (i.e. the use of the comma).

The best/only options we can do is to use MadSpin.
What is the issue that you face with MadSpin? From the syntax that you use it should in principle be supported.

Cheers,

olivier

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Marzieh Bahmani (marziehbahmani) said : 		#3

Hi Olivier,

thanks for your reply,
Unfortunately we can not use Madspin for the decay as I tried it already,
you can see it here:
https://bugs.launchpad.net/mg5amcnlo/+bug/2022069

Cheers,

Marzieh

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Olivier Mattelaer (olivier-mattelaer) said : 		#4

Actually you can use madspin in this case (in the full/normal mode).
The other option is to do something like

generate pp > l l pi [QCD]

(maybe the following might be ok --but please check the diagram generated--)
generate pp > n1 > l l pi [QCD]

Cheers,

Olivier

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