Pythia error while merging NLO event

Asked by Jack Y. Araz on 2020-06-21

Dear Mg5 Team;

Hope everyone is safe and healthy. I'm having a problem with merging an NLO process. I'm using DMsimp model and trying to reproduce the past studies by generating

generate p p > xd xd~ j / y0 [QCD]
add process p p > xd xd~ j j / y0 [QCD]

using a restrict card to have either vector or axial vector mediator etc. I'm using FxFx merging with pythia8 where my ptj in the run card is 20 GeV and ickkw = 3 and in shower card im only changing qcut to 30 and njet to 2. I'm also modifying cuts.f to set leading jet pt > 150 GeV and MET > 250 GeV. MG5 generates the born level events without any issue but I get the attached error for Pythia. Note that I only saw this issue with this sample, I can generate this very event with a single jet without any issue in Pythia. Would be appreciated if you can help me to solve this problem.

Thanks a lot and stay safe
Best regards
Jack

----------------

MG5 Version
version = 2.6.5
date = 2018-02-03

--------mcatnlo.log:

/mt/batch/jaraz/MG5_aMC_v2_6_5/HEPTools/pythia8/lib/libpythia8.a(Streams.o): In function `Pythia8::gzstreambuf::open(char const*, int)':
Streams.cc:(.text+0xfc): undefined reference to `gzopen'
/mt/batch/jaraz/MG5_aMC_v2_6_5/HEPTools/pythia8/lib/libpythia8.a(Streams.o): In function `Pythia8::gzstreambuf::close()':
Streams.cc:(.text+0x17f): undefined reference to `gzclose'
/mt/batch/jaraz/MG5_aMC_v2_6_5/HEPTools/pythia8/lib/libpythia8.a(Streams.o): In function `Pythia8Pythia8 compilation did not succeed, exiting
t+0x2be): undefined reference to `gzread'
/mt/batch/jaraz/MG5_aMC_v2_6_5/HEPTools/pythia8/lib/libpythia8.a(Streams.o): In function `Pythia8::gzstreambuf::flush_buffer()':
Streams.cc:(.text+0x382): undefined reference to `gzwrite'
/mt/batch/jaraz/MG5_aMC_v2_6_5/HEPTools/pythia8/lib/libpythia8.a(PartonDistributions.o): In function `Pythia8::LHAPDF::LHAPDF(int, std::__cxx11::basic_string<char, std::char_traits\
<char>, std::allocator<char> >, Pythia8::Info*)':
PartonDistributions.cc:(.text+0x1064b): undefined reference to `dlopen'
PartonDistributions.cc:(.text+0x10661): undefined reference to `dlerror'
PartonDistributions.cc:(.text+0x10809): undefined reference to `dlerror'
/mt/batch/jaraz/MG5_aMC_v2_6_5/HEPTools/pythia8/lib/libpythia8.a(PartonDistributions.o): In function `Pythia8::LHAPDF::~LHAPDF()':
PartonDistributions.cc:(.text+0x10d26): undefined reference to `dlclose'
PartonDistributions.cc:(.text+0x10d2b): undefined reference to `dlerror'
/mt/batch/jaraz/MG5_aMC_v2_6_5/HEPTools/pythia8/lib/libpythia8.a(PartonDistributions.o): In function `Pythia8::LHAPDF::symbol(std::__cxx11::basic_string<char, std::char_traits<char\
>, std::allocator<char> >)':
PartonDistributions.cc:(.text+0x10e87): undefined reference to `dlsym'
PartonDistributions.cc:(.text+0x10e90): undefined reference to `dlerror'
PartonDistributions.cc:(.text+0x10f1f): undefined reference to `dlerror'
collect2: error: ld returned 1 exit status
make: *** [Pythia82] Error 1

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
2020-06-24
Last query:
2020-06-24
Last reply:
2020-06-23

Hi,

1) Note that FxFx merging is not valid when you have a jet at the lowest multiplicity. (which is your case above)
2) Your error is a compilation error which fails to link quite basic function. Looks like you have an issue with your zlib libraries.
  Looks like you are either not link to it, or that one changed since the installation of pythia8.

Cheers,

Olivier

Jack Y. Araz (jackaraz) said : #2

Dear Oliver

Thanks for the quick response.

> 1) Note that FxFx merging is not valid when you have a jet at the lowest multiplicity. (which is your case above)
Thanks will try it as soon as I fix pythia problem.

> 2) Your error is a compilation error which fails to link quite basic function. Looks like you have an issue with your zlib libraries.
> Looks like you are either not link to it, or that one changed since the installation of pythia8.
I reinstalled both zlib and pythia then regenerate the sample from scratch but I’m still having the very same error. Is there a way to enforce pythia to use the zlib installed by mg5? I’m running it at the ip3 server, maybe its picking the zlib libraries installed in the other machines.

Thanks a lot
Best regards


Jack Y. Araz

> On Jun 22, 2020, at 9:01 AM, Olivier Mattelaer <email address hidden> wrote:
>
> Your question #691435 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/691435
>
> Status: Open => Answered
>
> Olivier Mattelaer proposed the following answer:
> Hi,
>
> 1) Note that FxFx merging is not valid when you have a jet at the lowest multiplicity. (which is your case above)
> 2) Your error is a compilation error which fails to link quite basic function. Looks like you have an issue with your zlib libraries.
> Looks like you are either not link to it, or that one changed since the installation of pythia8.
>
> Cheers,
>
> Olivier
>
> --
> If this answers your question, please go to the following page to let us
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>
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> following page to enter your feedback:
> https://answers.launchpad.net/mg5amcnlo/+question/691435
>
> You received this question notification because you asked the question.

This is likely a pythia8 bug that forget to keep track of that dependencies.
overwritting LD_LIBRARY_PATH is likely a work around

Cheers,

Olivier

Jack Y. Araz (jackaraz) said : #4

Thanks Olivier Mattelaer, that solved my question.