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Cross section calculation

Warning

This page is under construction

Cross sections can be calculated for MC samples.

To account for the different running conditions in Run 1 vs Run 2, click the appropriate tab below for Run 1 vs Run 2 data.

  • This page is under construction

  • You can calculate a cross section using the GenXSecAnalyzer. To use it, you will need the file ana.py, which you can get by curl https://raw.githubusercontent.com/cms-sw/genproductions/master/Utilities/calculateXSectionAndFilterEfficiency/genXsec_cfg.py -o ana.py

  • Next, fetch a CMSSW image and start a container. You can find a list of Docker container images available for CMS open data in the guide page for CMS open data containers. A tutorial on working with docker is at CMS open data containers. If you named your container my_od, you can fetch and start it by

docker start -i my_od

cd CMSSW_7_6_7/src
  • Then, copy the file ana.py to your container. 
curl https://raw.githubusercontent.com/cms-sw/genproductions/master/Utilities/calculateXSectionAndFilterEfficiency/genXsec_cfg.py -o ana.py
  • To compute the cross-section, type cmsRun ana.py inputFiles="file:xxxx.root" maxEvents=-1 in case you have copied one file locally or cmsRun ana.py inputFiles="root://eospublic.cern.ch//eos/opendata/cms/mc/[....].root" maxEvents=-1 if you access the file through xrootd protocol from the CERN Open data portal. For example:
cmsRun ana.py inputFiles="root://eospublic.cern.ch//eos/opendata/cms/mc/RunIIFall15MiniAODv2/TGJets_TuneCUETP8M1_13TeV_amcatnlo_madspin_pythia8/MINIAODSIM/PU25nsData2015v1_76X_mcRun2_asymptotic_v12-v1/00000/1A454199-F8B8-E511-A55D-7845C4FC374C.root" maxEvents=-1

  • After running the above commands, you will get a log file.

  • A cross-section summary will be printed out. The definition of each quantity is:

    • Before matching: the cross section before jet matching and any filter
    • After matching: the cross section after jet matching BUT before any filter
    • Filter efficiency: the efficiency of the any filter.
    • After filter: the cross section after jet matching and additional filter are applied. This is your final cross section.

  • You can use any CMS Run2 Open Data MC sample for testing, the example above is from Simulated dataset TGJets_TuneCUETP8M1_13TeV_amcatnlo_madspin_pythia8 in MINIAODSIM format for 2015 collision data.