B-Tagging cut flow

Algorithm/Algtool Task Cuts
BJetBuilder retrieves Jet/ParticleJet collection and TrackParticle container. Calls tool for TrackParticle - Jet association. Calls BTagTool for every Jet in the input collection cuts on the jet: PtMin = 10*GeV, EtaMax = 2.5, NbTrackMin = 1. but these cuts are bypassed by default with TagJetIfNotSelected = True
BTagTool sets general JetTag datamembers (4 mom, aso.). Calls truth matching tool (if no truth match possible, it is set to "N/A". retrieves primary vertex container. If there is no primary vertex no tag tool is called. BTagTool returns SC::Success to BJetBuilder.
TagTools each tool does a dedicated tag (lifetime, secvtx) Loops over the TrackParticles in the Jet and selects them: pt > 1.GeV, d0 to primary vertex < 1 mm, z0 to pri vtx < 1.5 mm, precision hits (pixel + sct) >= 9, Pixel hits >= 2, B-layer hits >= 1.
SecVtxTool special cuts also cut on a0/sig(a0) > 1. and in the vertex fit: chi2 per track < 4. and distance between primary and secondary vertex > 0.2 mm

Conclusion: when is a Jet not tagged

Algorithm/Algtool Stops tagging
BJetBuilder never, all jets are passed through unless TagJetIfNotSelected is set to False via job options
BTagTool stops if there is no primary vertex in the event. No tag at all will be called. The info map of the JetTag object has size 1 and will contain the TruthInfo object only.
LifetimeTag stops if a Jet has less than 2 good tracks, no info object will be appended to the JetTag object
SecVtxTag stops if a Jet has less than 2 good tracks, no info object will be appended to the JetTag object in addition does not give a usefull tag if no secondary vertex could be fitted. however in this case a info object will be given to the JetTag object which also will be used for tagging ... Advice: when reading the sec vtx info part of the JetTag check for the variable SecVtxInfo::fitType() not equal SecVtxInfo::NoFit

-- DerSchrecklicheSven - 23 May 2005

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Topic revision: r2 - 2005-05-30 - AndreasWildauer
 
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