events generated but not other output files

Asked by Can Kilic on 2017-08-05

I am using the Feynrules simplifed dark matter model (http://feynrules.irmp.ucl.ac.be/wiki/DMsimp) to generate the process 'p p > j Y1' (Y1 is a Zprime that will be assumed to decay invisibly) in MG5 version 2.5.5. The parton level run completes without any error messages, and generates an event file and the banner, but only those two files - all other files that should be in the Events directory (run_shower etc etc) are missing. Also, when I try to follow the parton level run with a pythia8 run, the pythia 8 run starts but immediately stalls (it does not crash or output any error message, it just becomes unresponsive).

I realize this may be a model-specific issue but since I get no error messages I don't know what is causing the problem. I would be happy to provide any model files, or cards from the working directory if it helps diagnose the problem (should I copy/paste them here? I don't see an option to attach files)

Thanks.

Question information

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

Hi,

I do not reproduce such problem with 2.5.6 (still in development). Therefore without that many information, it's difficult for me to guess what the solution is.
Sorry if it will require a lot of email exchange/work on your side to fix this.

We had a series of problem with pythia8 in 2.5.5, mainly related to user using python 2.6.x. Is it your case?
If it is, can you try to use python 2.7.x
Another solution is to run pythia8 on a single core. (set nb_core 1)

This being said, that problem sound different than yours so I doubt that this will fix your problem.
Do I understand correctly that you have no problem for SM processes? (Like p p > t t~)
But only for this model?

When the code stalls, can you run the ps command and the top command. To see if the freezing is inside py8 or inside MG5aMC (python side)

Cheers,

Olivier

> On 5 Aug 2017, at 23:53, Can Kilic <email address hidden> wrote:
>
> New question #655371 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/655371
>
> I am using the Feynrules simplifed dark matter model (http://feynrules.irmp.ucl.ac.be/wiki/DMsimp) to generate the process 'p p > j Y1' (Y1 is a Zprime that will be assumed to decay invisibly) in MG5 version 2.5.5. The parton level run completes without any error messages, and generates an event file and the banner, but only those two files - all other files that should be in the Events directory (run_shower etc etc) are missing. Also, when I try to follow the parton level run with a pythia8 run, the pythia 8 run starts but immediately stalls (it does not crash or output any error message, it just becomes unresponsive).
>
> I realize this may be a model-specific issue but since I get no error messages I don't know what is causing the problem. I would be happy to provide any model files, or cards from the working directory if it helps diagnose the problem (should I copy/paste them here? I don't see an option to attach files)
>
> Thanks.
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Can Kilic (kilic) said : #2

Hi Olivier,

Thanks for the quick response!

I updated from python 2.6.x to python 2.7.x but that did not make a difference. I also changed the run_mode to 0 and nb_core to 1 but that did not make a difference either.

Yes, I am not having any issues with other models, just this one.

By running 'top' I can see that the process that gets stuck is (multiple instances of) 'MG5aMC_PY8_inte'. In fact, I get multiple instances of 'MG5aMC_PY8_inte' even though I set run_mode to 0 and nb_core to 1 as I said above (is that normal?)

One thing I tried is to interrupt the pythia call initiated by MG5 and then run './run_shower' manually to look at the pythia output for further diagnosis. It does look like the quantum numbers for the new particles are read in correctly. It does complain that the zprime decay table is empty (I want to treat it as an invisible particle) but it seems to process the first event more or less as expected (the zprime just goes through the event record undecayed and the 'End PYTHIA event listing' line appears), but after that there is no output (no second event etc) so I assume it gets trapped in some infinite loop etc at that point.
One other thing I tried is modifying 'pythia8_card.dat' by adding '5000001:mayDecay = off' (5000001 is the particle code for the zprime in the model). When I do that I don't even get the first event - I get an error message that pythia does not recognize the particle code (even though as I said above, without the pythia card modification it seems to read in the quantum numbers for the zprime without any problem). And even though there is no output, pythia still gets stuck (does not crash and exit).

I'm sorry this is all such a riddle - still if you have any ideas about what might be going wrong, I would very much appreciate it.

Thanks,
Can

Ok,

With those informations, the best is that Valentin takes a look. He will probably forward this problem to PY8 authors,
since it sounds that (at least) part of the problem is out of our control.

Cheers,

Olivier

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