'LexToken' object has no attribute '__getitem__'

Asked by teddym on 2018-08-31

Dear MG authors:
   I made a new kind of propagators for fermion. I modified the propagators.py and particles.py files. When output the process, I got this Error message.

TypeError : 'LexToken' object has no attribute '__getitem__'

Where should I look at to solve this problem? Thanks!

Best

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
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Last query:
2018-09-02
Last reply:
2018-09-03

1) Check that you have the latest version of MG5_aMC (maybe even check the 2.6.4 version not yet released)
2) Add some print statement inside the code to understand what the problem is or send me your model such that I can have a look)

Cheers,

Olivier

> On 31 Aug 2018, at 22:27, teddym <email address hidden> wrote:
>
> New question #673188 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/673188
>
> Dear MG authors:
> I made a new kind of propagators for fermion. I modified the propagators.py and particles.py files. When output the process, I got this Error message.
>
> TypeError : 'LexToken' object has no attribute '__getitem__'
>
> Where should I look at to solve this problem? Thanks!
>
> Best
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

teddym (niepanchongsheng) said : #2

Hi Olivier:
    Thanks! The problem is that I use incorrect syntax for the propagator. And I find that when I modify the propagators.py, the allowed elements that I can use to construct the propagator are limited. So is that possible to add other object with lorentz index?

And if I shift the denominator of the propagator, will that be a problem for the MC simulation or MC integral?

Best

Hi,

> And I find that when I modify the propagators.py, the allowed elements that I can use to construct the propagator are limited.

Only those defined in the ALOHA/UFO paper are supported indeed.

> So is that possible to add other object with lorentz index?

No this is not possible to add additional lorentz object via the model.
What is missing?
Note that if you limit yourself to Fortran output, you can define arbitrary functions in a fortran file.
Those function should only take scalar as argument (for more information look at the wiki page on Form-Factor)

> And if I shift the denominator of the propagator, will that be a problem
> for the MC simulation or MC integral?

As long as the shift is much smaller than the width (the one written in the param_card), the integration should not be problematic.

Cheers,

Olivier

> On 3 Sep 2018, at 01:27, teddym <email address hidden> wrote:
>
> Question #673188 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/673188
>
> Status: Answered => Open
>
> teddym is still having a problem:
> Hi Olivier:
> Thanks! The problem is that I use incorrect syntax for the propagator. And I find that when I modify the propagators.py, the allowed elements that I can use to construct the propagator are limited. So is that possible to add other object with lorentz index?
>
> And if I shift the denominator of the propagator, will that be a problem
> for the MC simulation or MC integral?
>
> Best
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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