b Tag Analysis with CMSSW Framework Light (fwLite) in CMSSW 1.6

This is convenient for quickly looking at the data, with the bonus of being able to use the public member functions of any class stored in the event. You should first set up your CMSSW environment from inside your project area and start ROOT:

eval `scramv1 runtime -csh`
root

then make the CMSSW FWlite libraries available and open the dataset:

gSystem.Load("libFWCoreFWLite.so");
AutoLibraryLoader::enable();   

TRFIOFile f("/castor/cern.ch/cms/store/mc/2007/9/11/RelVal-RelValTTbar-1189470628/0000/22BEE924-7360-DC11-A1E0-001A92971B9C.root")

We can now set some aliases for B tag objects. (If you don't know the exact name of the B tag objects, check using TBrowser). While defining aliases is not necessary, it does make the subsequent analysis much simpler:

Events->SetAlias("bmu", "recoJetTags_softMuonJetTags__Rec.obj");
Events->SetAlias("bmuInfo", "recoSoftLeptonTagInfos_softMuonTagInfos__Rec.obj");

We can now make histograms, using the public member functions of any classes in the Event. (Note that because JetTag::jet() returns a RefToBase, one must use function RefToBase::get() to access the Jet).

// Plot b "soft muon" tag discriminator for jets with pT > 50 GeV
Events->Draw("bmu.discriminator()","bmu.jet().get().pt()>50")

One can also make more detailed plots (not shown) using the TagInfo:

// Plot the number of muons in the jet.
Events.Draw("bmuInfo->leptons()") 
// Plot the Pt spectrum relative to the jet of the first muon.
// (N.B. Unfortunately, if multiple muons are present,
// they are not ordered in any special way).
Events.Draw("bmuInfo->properties(0).ptRel","bmuInfo->leptons()>0")

-- IanTomalin - 24 Oct 2007

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Topic revision: r7 - 2008-02-27 - AreshVedaee
 
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