MadGraph5_aMC@NLO

TypeError : 'LexToken' object has no attribute '__getitem__' for q q~ > anything

Asked by Lara Mason

Hi experts,

I'm implementing a new model in MadGraph, but when I try to check processes like p p > anything, I get

Command "check p p > a a" interrupted with error:
TypeError : 'LexToken' object has no attribute '__getitem__'
Please report this bug on https://bugs.launchpad.net/mg5amcnlo
More information is found in 'MG5_debug'.
Please attach this file to your report.

There is, however, no problem when I run "check g g > a a". So the problem only seems to occur for the quarks.

I can't find any obvious syntax errors, but perhaps I am missing some.

Please let me know if I can attach the debug file somewhere.

Thanks very much,

Lara

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MadGraph5_aMC@NLO Edit question
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Solved by:
Olivier Mattelaer
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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

The debug file, will be useless here.
What I would need is the model file. You can either send it to me by email (with a link to this webpage such that I can make the link)
or you can create a bug report with the model in attachment.

But indeed this is likely to be a problem with some of your lorentz structure definition and/or with the definition of the coupling

Cheers,

Olivier

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Best Olivier Mattelaer (olivier-mattelaer) said : 		#2

Hi,

The problem is indeed in lorents.py
I see the following:
FFS2 = Lorentz(name = 'FFS2',
               spins = [ 2, 2, 1 ],
               structure = 'Gamma5()*ProjM(2,1) - Gamma5()*ProjP(2,1)')

The Gamma5 object is a matrix which needs two index.
I guess that the correct syntax should be
FFS2 = Lorentz(name = 'FFS2',
               spins = [ 2, 2, 1 ],
               structure = 'Gamma5(2,-1)*ProjM(-1,1) - Gamma5(2,-1)*ProjP(-1,1)')
But this might not be it.

Cheers,

Olivier

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Lara Mason (laram) said : 		#3

Thanks Olivier Mattelaer, that solved my question.

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Lara Mason (laram) said : 		#4

Thank you so much for your help!