The Trimmed Kalman vertex reconstructor

Complete: 2

Overview

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

Usage

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 );

Parameters

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 NameSorted descending Description Default method
vertexFitProbabilityCut the probability below which a vertex is rejected 0.01 setVertexFitProbabilityCut(float)
trackCompatibilityToSVcut the probability below which a track is considered incompatible with the next vertex candidates formed. 0.01 setTrackCompatibilityToSV(float)
trackCompatibilityToPVcut the probability below which a track is considered incompatible with the 1st vertex candidate formed. 0.05 setTrackCompatibilityCut(float)
ptCut the minimum pT (in GeV) of the tracks used to make vertices. 1.5 setPtCut(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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