The Trimmed Kalman vertex reconstructor

Complete: 2


The Trimmed Kalman vertex reconstructor iteratively uses the Trimmed Kalman vertex fitter to find and fit interaction vertices. After each fitted vertex, the remaining tracks are re-used to search for further vertices.

The fitter is implemented in the package RecoVertex/TrimmedKalmanVertexFinder


A default An easy way to use the TKVF is through the KalmanTrimmedVertexFinder. It uses a conventional Kalman filter to fit the vertices, without the user having to specify anything. It is then used like any other VertexReconstructor.
KalmanTrimmedVertexFinder finder;
vector<TransientVertex> vertices = finder.vertices ( vector<TransientTrack> tracks );


To change the parameters, the easiest is to use the setParameters(ParameterSet) method. Alternatively, individual set methods can be used. The PSet needed is the following:

GSFParameters = cms.PSet(
   ptCut = cms.double(0.0),
   vtxFitProbCut = cms.double(0.01),
   trackCompatibilityToPVcut = cms.double(0.05),
   trackCompatibilityToSVcut = cms.double(0.01),
   maxNbOfVertices = cms.int32(0)

The parameters are the following:

Parameter Name Description Default method
ptCut the minimum pT (in GeV) of the tracks used to make vertices. 1.5 setPtCut(float)
trackCompatibilityToPVcut the probability below which a track is considered incompatible with the 1st vertex candidate formed. 0.05 setTrackCompatibilityCut(float)
trackCompatibilityToSVcut the probability below which a track is considered incompatible with the next vertex candidates formed. 0.01 setTrackCompatibilityToSV(float)
vertexFitProbabilityCut the probability below which a vertex is rejected 0.01 setVertexFitProbabilityCut(float)
maxNbOfVertices the maximum number of vertices searched for. 0 means no limitations 0 setMaxNbOfVertices(int)

-- Main.speer - 05 Jul 2007

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Topic revision: r2 - 2009-03-11 - ThomasSpeer
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