MadGraph5_aMC@NLO

Reaching end of LHE file, efficiency problem

Asked by Marija Glisic

Hi,

I am running a generation sample which uses MadGraph for the hard scatter, and Pythia for the later scattering. Due to a low ktdurham cut we use, the Pythia step has very low efficiency. When running 10k events only 8085 events were generated before reaching the end of the LHE file. Is there a way to make the LHE file contain more events? Or is there some other work-around? I'd prefer to not increase ktdurham. I've included part of the log.generate below. This is run using AthGeneration 21.6.42

04:07:29 Pythia::next(): 9000 events have been generated
04:09:54
04:09:54 Pythia::next(): 1000 events have been generated
04:09:58 PYTHIA Error in SimpleSpaceShower::pT2nearThreshold: stuck in loop
04:10:13
04:10:13 Pythia::next(): 10000 events have been generated
04:13:00 PerfMonSvc: INFO [evt: 4160] cpu= 102.000 ms vmem=1300.957 Mb dvmem= 0.250 Mb alloc= +0 -0 0.000 kb => [/evt/PerfMonSlice]
04:13:00
04:13:00 Pythia::next(): 11000 events have been generated
04:15:02 PYTHIA Warning in SimpleSpaceShower::pT2nextQCD: small daughter PDF
04:15:03 FixHepMC INFO Particles filtered: 2231 -> 2230
04:15:20 PYTHIA Warning in Pythia::check: energy-momentum not quite conserved
04:15:40
04:15:40 Pythia::next(): 12000 events have been generated
04:18:33
04:18:33 Pythia::next(): 13000 events have been generated
04:21:25
04:21:25 Pythia::next(): 14000 events have been generated
04:24:17
04:24:17 Pythia::next(): 15000 events have been generated
04:25:33 FixHepMC INFO Particles filtered: 1418 -> 1417
04:27:07
04:27:07 Pythia::next(): 16000 events have been generated
04:29:53
04:29:53 Pythia::next(): 17000 events have been generated
04:32:56
04:32:56 Pythia::next(): 18000 events have been generated
04:35:48
04:35:48 Pythia::next(): 19000 events have been generated
04:36:52 FixHepMC INFO Particles filtered: 2629 -> 2628
04:37:56
04:37:56 Pythia::next(): 2000 events have been generated
04:38:29
04:38:29 Pythia::next(): 20000 events have been generated
04:38:29 PYTHIA Abort from Pythia::next: reached end of Les Houches Events File
04:38:29 Pythia8 INFO Event generation failed - re-trying.
04:38:29 Pythia8 INFO Event generation failed - re-trying.
04:38:29 Pythia8 INFO Event generation failed - re-trying.
04:38:29 Pythia8 INFO Event generation failed - re-trying.
04:38:29 Pythia8 INFO Event generation failed - re-trying.
04:38:29 Pythia8 INFO Event generation failed - re-trying.
04:38:29 Pythia8 INFO Event generation failed - re-trying.
04:38:29 Pythia8 INFO Event generation failed - re-trying.
04:38:29 Pythia8 INFO Event generation failed - re-trying.
04:38:29 Pythia8 ERROR Exceeded the max number of consecutive event failures.
04:38:29 Pythia8 FATAL /build/atnight/localbuilds/nightlies/21.6/athena/Generators/GeneratorModules/src/GenModule.cxx:56 (StatusCode GenModule::execute()): code 0: this->callGenerator()
04:38:29 EvgenGenSeq INFO execute of [Pythia8] did NOT succeed
04:38:29 AthMasterSeq INFO execute of [EvgenGenSeq] did NOT succeed
04:38:29 AthenaEventLoopMgr ERROR Terminating event processing loop due to errors
04:38:29 CutFlowSvc INFO CutBookkeeper CutBookkeepers N/A EvgenFilterSeq Cyc=0 N=0 weight^2=0
04:38:29 StorageSvc Info Building shape according to reflection information using shape ID for:
04:38:29 StorageSvc Info EventStreamInfo_p3 [11DF1B8C-0DEE-4687-80D7-E74B520ACBB4]
04:38:29 ClassIDSvc INFO getRegistryEntries: read 5 CLIDRegistry entries for module ALL
04:38:30 StorageSvc Info Building shape according to reflection information using shape ID for:
04:38:30 StorageSvc Info IOVMetaDataContainer_p1 [6C2DE6DF-6D52-43F6-B435-9F29812F40C0]
04:38:30 ClassIDSvc INFO getRegistryEntries: read 9 CLIDRegistry entries for module ALL
04:38:30 StreamEVGEN INFO Records written: 8085
04:38:31 C1N2N1.EVGEN.pool.root Info Database being retired...
04:38:31 Domain[ROOT_All] Info -> Deaccess DbDatabase CREATE [ROOT_All] D94DB17A-0B86-9D49-B8D7-4B81DF6B48F6
04:38:31 Domain[ROOT_All] Info > Deaccess DbDomain UPDATE [ROOT_All]
04:38:31 ApplicationMgr INFO Application Manager Stopped successfully
04:38:31 Pythia8 INFO >>> Pythia8_i from genFinalize

Thank you,
Marija Glisic

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

You can ask to generate more than 10k events in MG5aMC, and ask pythia8 to stop after having 10k events passing the selection.
In principle you have an entry in the pythia8 that control the number of events but I do not know if this is the number of events read or the number of events passing the selection. I would advise you to check that within the pythia8 manual.

Cheers,

Olivier

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