Backporting MC jet flavour definition from CMSSW 9 to CMSSW 8

Intro

This adds in the new jet flavour definition into CMSSW 8. It updates the partonFlavor() attribute of a pat::Jet collection.

In this new method, you recluster each jet's constituents along with all genpartons as “ghosts”, then pick the highest pT genparton that gets clustered, irrespective of status.
This way it can work for both Pythia and Herwig (in the former it often corresponds to status==23 particle anyway for MG+Pythia8).

https://github.com/cms-sw/cmssw/pull/19048
https://github.com/cms-sw/cmssw/pull/20281/
https://github.com/cms-sw/cmssw/pull/20840/

https://indico.cern.ch/event/649196/contributions/2641282/attachments/1483715/2302215/JetFlavour.pdf

In terms of modules, this is how the partonFlavour gets calculated normally:

  • A HadronAndPartonSelector EDProducer produces collections of partons, leptons, bHadrons, and cHadrons from some input collection (often genParticles) according to some selection criteria. This is the critical part that determines which gen particles can be used for the flavour definition.
  • A JetFlavourClustering EDProducer takes in these collections, along with some jet collection, and does the ghost reclustering. The jet<>flavour info is stored as a JetFlavourInfoMatchingCollection, which is really a edm::AssociationVector<edm::RefToBaseProd<reco::Jet>,std::vector<reco::JetFlavourInfo> > (i.e. a map between a reference to a Jet, and a JetFlavourInfo object)
This is normally done on reco::Jet when making the MiniAOD, and gets stored when the pat::Jets are made.

However, if you just want to run over MiniAOD you will need another module to update the pat::Jets (which I have written).

Instructions

blah

-- RobinAggleton - 2017-12-08

Edit | Attach | Watch | Print version | History: r6 | r4 < r3 < r2 < r1 | Backlinks | Raw View | Raw edit | More topic actions...
Topic revision: r2 - 2017-12-11 - RobinAggleton
 
    • Cern Search Icon Cern Search
    • TWiki Search Icon TWiki Search
    • Google Search Icon Google Search

    Main All webs login

This site is powered by the TWiki collaboration platform Powered by PerlCopyright &© 2008-2020 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki? Send feedback