MadGraph5_aMC@NLO

std::bad_alloc

Asked by Joel Jones

Hi, I just downloaded MG5_aMC v2.5.4, and am having issues running Pythia8. The files cannot be combined, and every now and then I get a:

terminate called after throwing an instance of 'std::bad_alloc'
 what(): std::bad_alloc

Thus, I only get parton-level results. No idea what could be causing this. I have installed everything using the included installers.

Cheers, thanks.

Joel

PS: By the way, I am aware of: https://answers.launchpad.net/mg5amcnlo/+question/431696 , still, won't work.

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Olivier Mattelaer
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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

You should contact pythia8 author on that topic.
Can not help you on this point.

Cheers,

Olivier

> On 12 Apr 2017, at 07:23, Joel Jones <email address hidden> wrote:
>
> New question #616776 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/616776
>
> Hi, I just downloaded MG5_aMC v2.5.4, and am having issues running Pythia8. The files cannot be combined, and every now and then I get a:
>
> terminate called after throwing an instance of 'std::bad_alloc'
> what(): std::bad_alloc
>
> Thus, I only get parton-level results. No idea what could be causing this. I have installed everything using the included installers.
>
> Cheers, thanks.
>
> Joel
>
> PS: By the way, I am aware of: https://answers.launchpad.net/mg5amcnlo/+question/431696 , still, won't work.
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Revision history for this message
Joel Jones (n-jones-j) said : 		#2

Sorry, I turned off Pythia8 and am still getting the result.

Let me be a bit more clear on this. The parton-level calculation apparently finishes, as I get a cross-section. However, the status on the browser remains in "Combining Events."

If I re-run MadEvent, I get:
root: Another instance of the program is currently running.
                (for this exact same directory) Please wait that this is instance is
                closed. If no instance is running, you can delete the file
                /home/jjones/Programs/MG5_aMC_v2_5_4/example2/RunWeb and try again.

And every other time, apart from this problem, I get the 'std::bad_alloc'. Sorry, I initially thought it was a MG - Pythia8 issue, as a Google search indicated this was a c++ message. But now I am not sure.

Revision history for this message
Best Olivier Mattelaer (olivier-mattelaer) said : 		#3

Hi,

Sorry i was in paternity leave sine the 12. So I only see your message now.
Do you have the final lhe file?
If yes, this might be a problem of lhapdf during the computation of the systematics.
If that's the case, you can turn off the systematics computation by setting in your run_card
none = systematics_program

If you have installed SysCalc, you can also do
syscalc = systematics_program

Cheers,

Olivier

Revision history for this message
Joel Jones (n-jones-j) said : 		#4

Yes! turning off systematics fixed the problem.

Strange, I do not have the same problem in other computers, and this one persists even though I re-installed both MadGraph and LHAPDF.

Thank you very much, and congratulations on the paternity. :-)

Revision history for this message
Joel Jones (n-jones-j) said : 		#5

Thanks Olivier Mattelaer, that solved my question.