Generating Events

Hi folks! I am trying to generate events in lxplus, specifically of which just of a standard model signature (gg → ttbar). I follow the three step procedures, (1) GEN-SIM, (2) DIGI-HLT, and finally (3) RECO. For this, I have the following:

(1) GEN-SIM : I used the generator fragment found in the workbook documentation. And so, I did --fileout file:gg2ttbar_13TeV_pythia8_withoutPU_GEN-SIM.root --mc --eventcontent RAWSIM --datatier GEN-SIM --conditions auto:mc --step GEN,SIM --python_filename --no_exec --geometry DB:Extended --era Run2_2018 --customise Configuration/DataProcessing/Utils.addMonitoring -n 10

I got a root file output, and so this can now be used for step (2). What I did after is:

(2) DIGI-HLT : I closely followed the example found in this documentation. Of which, for the no pileup input, I ended up creating the configuration file with the command --filein file:gg2ttbar_13TeV_pythia8_withoutPU_GEN-SIM.root --python_filename --fileout file:gg2ttbar_13TeV_pythia8_digiToRecoStep_withoutPU.root --eventcontent AODSIM --customise Configuration/DataProcessing/Utils.addMonitoring --datatier GEN-SIM-DIGI-RAW  --conditions auto:mc --step DIGI,L1,DIGI2RAW,HLT:@relval2018 --nThreads 8 --geometry DB:Extended --era Run2_2018 --no_exec --mc -n 1

of which results to an error

----- Begin Fatal Exception 21-Mar-2024 15:53:09 CET-----------------------
An exception of category 'NoRecord' occurred while
   [0] Processing global begin Run run: 1
   [1] Calling method for module L1TMuonOverlapTrackProducer/'simOmtfDigis'
Exception Message:
No "L1TMuonOverlapParamsRcd" record found in the EventSetup.n
 Please add an ESSource or ESProducer that delivers such a record.
----- End Fatal Exception -------------------------------------------------
DQMStore: WARNING: attempt to remove non-existent monitor element 'throughput_retired' in 'HLT/Throughput'
DQMStore: WARNING: attempt to remove non-existent monitor element 'throughput_sourced' in 'HLT/Throughput'
21-Mar-2024 15:53:09 CET  Closed file file:gg2ttbar_13TeV_pythia8_withoutPU_GEN-SIM.root

I also noticed that this happens to be the error even if i used @fake in step instead of @relval2018. What seems to be the issue here? How can I proceed to the RECO step after this?

Hi Resham,

Can you share more details of your environment? You say you’re on lxplus, and you seem to be attempting to generate 2018 conditions, so this doesn’t immediately sound like Open Data usage. It would be helpful to clarify what the goals are, which CMSSW, etc.

The main Open Data guide for event production is here: CMS Guide to generate configuration files for event production | CERN Open Data Portal

If you need 13 TeV ttbar simulation for Open Data usage, I recommend these existing samples:

On those sample’s record pages you can find examples of the configuration files for each step that might prove a little more helpful than cmsDriver commands on the Workbook, which are not stable for Open Data. For the LHE step the example file corresponds directly to the sample recorded on that page. For later steps the input/output file names are just examples.

Let me know if that helps or you need more information,


Thank you a bunch for your help and resources! I appreciate it ^^