MadGraph5_aMC@NLO

MG events not going to Pythia/Delphes

Asked by Samuel Homiller

Hi Experts,
I'm attempting to simulate p p > t t~ a at LO, with showering and detector simulation done by Pythia6 and Delphes respectively. Everything on my setup seems to work fine for most processes, but for some reason when I try to generate 50k events for this process, only a small fraction (~500) of the events seem to pass to Pythia and Delphes after the parton level generation.

I've tried checking the logs from each step in the process, but I don't see any obvious issues, except that the number of events changes between the parton level and Pythia level. There aren't any errors thrown, so there's no debug logs to check either.

Is there some obvious reason why this might be happening? Thanks very much for the help

Sam

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Samuel Homiller (shomiller) said : 		#1

For reference, this is the .txt file I passed to MG5 to run in batch mode:

generate p p > t t~ a
output /export/scratch2/shomiller/dihiggs_ATLAS_14TEV_oldbtagperf/TTA_BKG/batch_851_0/
launch /export/scratch2/shomiller/dihiggs_ATLAS_14TEV_oldbtagperf/TTA_BKG/batch_851_0/
shower=PYTHIA6
delphes=ON
analysis=OFF
set nevents 50000
set ebeam1 7000.0
set ebeam2 7000.0
set ptj 0.0
set pta 0.0
set etaa -1.0
set mmjj 0.0
set mmaa 0.0
set mmaamax -1.0
set mmbb 0.0
/export/scratch2/shomiller/dihiggs_ATLAS_14TEV_oldbtagperf/ATLAS_dihiggs.tcl
launch /export/scratch2/shomiller/dihiggs_ATLAS_14TEV_oldbtagperf/TTA_BKG/batch_851_0/ -i
print_results --path=/export/scratch2/shomiller/dihiggs_ATLAS_14TEV_oldbtagperf/TTA_BKG/batch_851_0/csx_TTA.txt

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Olivier Mattelaer (olivier-mattelaer) said : 		#2

Hi,

You do not have any cut on the photon, therefore your matrix-element as a singularity which is "naked".
In that case it is impossible to generate unweighted events.

Cheers,

Olivier

> On 7 Jul 2017, at 17:47, Samuel Homiller <email address hidden> wrote:
>
> Question #646941 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/646941
>
> Samuel Homiller gave more information on the question:
> For reference, this is the .txt file I passed to MG5 to run in batch
> mode:
>
> generate p p > t t~ a
> output /export/scratch2/shomiller/dihiggs_ATLAS_14TEV_oldbtagperf/TTA_BKG/batch_851_0/
> launch /export/scratch2/shomiller/dihiggs_ATLAS_14TEV_oldbtagperf/TTA_BKG/batch_851_0/
> shower=PYTHIA6
> delphes=ON
> analysis=OFF
> set nevents 50000
> set ebeam1 7000.0
> set ebeam2 7000.0
> set ptj 0.0
> set pta 0.0
> set etaa -1.0
> set mmjj 0.0
> set mmaa 0.0
> set mmaamax -1.0
> set mmbb 0.0
> /export/scratch2/shomiller/dihiggs_ATLAS_14TEV_oldbtagperf/ATLAS_dihiggs.tcl
> launch /export/scratch2/shomiller/dihiggs_ATLAS_14TEV_oldbtagperf/TTA_BKG/batch_851_0/ -i
> print_results --path=/export/scratch2/shomiller/dihiggs_ATLAS_14TEV_oldbtagperf/TTA_BKG/batch_851_0/csx_TTA.txt
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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