MadGraph5_aMC@NLO

Poles do not cancel error when trying to generate process g g > h > z z > 4 leptons with SMEFT model

Asked by Jay Sandesara

Hello, I am trying to generate process g g > h > z z > 4 leptons using the command:

" g g > h > l+ l- l+ l- NP=2 QCD=2 QED=4 [QCD] /a b s c u d "

with

"import model SMEFTatNLO_U2_2_U3_3_cG_4F_LO_UFO-full"

but I keep getting the following error:

Error detected in "launch auto "
write debug file /eos/home-j/jsandesa/MG5_aMC_v2_6_5/ggTohTOzzToleptons/run_01_tag_1_debug.log
If you need help with this issue please contact us on https://answers.launchpad.net/mg5amcnlo
aMCatNLOError : Poles do not cancel, run cannot continue

The event generation works well when I simply use:

"import model SMEFTatNLO_U2_2_U3_3_cG_4F_LO_UFO" or "import model SMEFTatNLO_U2_2_U3_3_cG_4F_LO_UFO-NLO"

Problem is, I need both Born diagrams and NLO diagrams for my analysis.

Is there a way I can include both without the errors?

Thanks!

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

HI,

The following syntax does not make ANY sense at NLO:
g g > h > l+ l- l+ l- NP=2 QCD=2 QED=4 [QCD] /a b s c u d

Indeed one expect the code to crash with such syntax (you will fail to include some of the real contribution and therefore the pole will not correctly cancel with the loop)

They are two mistake in this syntax (for NLO computation)
1. you have to use "p" multi-particle in the initial state
2. you can not exclude light QCD particle from the process
so I would rather try the following syntax
p p > h > l+ l- l+ l- NP=2 QCD=2 QED=4 [QCD] /a

This being said I have no clue what your model is (and do not really understand your actual request in term of computation).
So I would suggest to contact the authors of the model who will be able to understand what kind of physics you are interested in.

Cheers,

Olivier

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