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Monte Carlo Validation

Goal

To write a package to do streamline Monte Carlo Validation. Action items:

  • Things to check for top:
    • W(qq) inv mass
    • W(lnu) inv mass distinguishing the three possible flavors
    • top (qqq) inv mass
    • top (qlnu) inv mass
    • dN/dn_genjet
    • 1st and 2nd associated jet pT and eta
    • branching ratio of ttbar decays (had vs semilep) vs ttbar

  • Things to check for Z and W
    • All similar, except the top mass of course.

Users

Procedures

Test files

  • /hdacs/shared/tt1j.root
  • /hdacs/shared/tt2j.root

CVS

The code is structured as an EDAnalyzer, located at the SPRACE CVS repository.

  • Set up CVS:
export CVSROOT=/hdacs/shared/cvsrepository

  • Check out the code - make sure to be inside a directory CMSSW_X_Y_Z/src/SomeAnalyzer beforehand!
cvs co ValidationAnalyzer

  • Check in the code after making changes.
cd CMSSW_X_Y_Z/src/SomeAnalyzer cvs ci ValidationAnalyzer

Links

Flavia's Log

  • To reconstruct t and tbar, I located the vertex that has a t (tbar) ingoing, and took the outgoing particles of the vertices. However, some of these top vertices also got particles other than the W and b: uubar, gluon. I've (under Thiago's advice) just ignored it and tried to reconstruct the top mass with just W's and b's. Solved: status 2 particles.

  • Status stuff - status 2 particles for showering.

  • To compile with TFileService, take care to put the lines in the BuildFile in the right place (lines above, not below).

  • Successfully reconstructed invariant mass of the W's from hadronic and leptonic decays.

  • Successfully reconstructed invariant mass of t and tbar from hadronic and leptonic decays.

  • For the jet reconstruction, what must be done is the following:
    • In the _cfg.py file: use a module that converts HepMC to GenParticles
    • In the _cfg.py file: use a module that makes GenJets.
    • In the ValidationAnalyzer file: get the GenJets with something like: edm::Handle<GenJetCollection>. Match those jets with the EXTRA partons - that means, if we are dealing with ttbar+2partons, you want to match those jets to the 2 partons, NOT to the ttbar or the b.
    • By "match" I really mean "the deltaR in between the parton and the jet is smaller than some number" - at least the size of the jet (usually 0.5), but preferably smaller.

  • The steps taken:
    • In the _cfg.py file: Added some processes: (process.load)
      • RecoJets/Configuration/RecoGenJetsAll_cff
      • RecoJets/Configuration/GenJetParticles_cff
      • RecoJets/JetProducers/sisCone5GenJets_cff
    • In the process . p = cms . Path:
      • process.genParticles * process.genParticlesForJets * process.sisCone5GenJets * process.demo
    • In the BuildFile:
      • use name=DataFormats/JetReco
    • Includes in the .cc code:
      • DataFormats/JetReco/interface/GenJet.h
      • DataFormats/JetReco/interface/GenJetCollection.h

-- ThiagoTomei - 20 Feb 2009 -- FlaviaDias - 17 Feb 2009

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Topic revision: r12 - 2009-05-12 - ThiagoTomei
 

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