pythia shower Error type 2 colour tag tracing failed

Asked by shenty1991 on 2017-08-06

Hello,

I am trying to generate some leptoquark enujj channel simulations. Pythia shower couldn't working and the log file gives:

Error type 2 has occured after 0 PYEXEC calls:
     (PYCTTR:) colour tag tracing failed

Has any one ever encountered this kind of issue before?

I can send you the cards I used if needed!

Thank you so much!

Simon

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
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Last query:
2017-08-07
Last reply:
2017-08-07

Hi,

This sounds a pure pythia problem. Can not really comment on this.
You should try to use PY8 instead of PY6.
Especially since PY6 is not supported anymore (neither buy their original author/pythia author or by us for that interface --especially since we have introduce a PY8 interface)

Cheers,

Olivier

shenty1991 (shenty1991) said : #2

Hello,

I just tried Pythia 8, and there are still problems:

 | 100 Error in ProcessLevel::checkColours: unphysical colour flow |
 | 100 Error in ProcessLevel::findJunctions: N(unmatched (anti)colour tags) != 3

My lhe file is here https://www.dropbox.com/sh/eet18ay1xkmp4xb/AAD08fvnGtp6YYZMpXdqI80Ja?dl=0

Thank you!

Simon

Hi,

The colour flow of your events seems to be perfectly valid to me.
They are like tt~ sample with decay in wb

Do not see anything wrong.

I would suggest to ask Pythia8 author.
And came back to us if they point an error inside that Lhe file.

Cheers,

Olivier

> On 7 Aug 2017, at 16:27, shenty1991 <email address hidden> wrote:
>
> Question #655403 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/655403
>
> Status: Answered => Open
>
> shenty1991 is still having a problem:
> Hello,
>
> I just tried Pythia 8, and there are still problems:
>
> | 100 Error in ProcessLevel::checkColours: unphysical colour flow |
> | 100 Error in ProcessLevel::findJunctions: N(unmatched (anti)colour tags) != 3
>
>
> My lhe file is here https://www.dropbox.com/sh/eet18ay1xkmp4xb/AAD08fvnGtp6YYZMpXdqI80Ja?dl=0
>
>
> Thank you!
>
> Simon
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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