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Table of Contents
Inclusive Vertex Finder (IVF)
The IVF will run out-of-the-box in CMSSW_5_3_11. If unsure, you can check out the following two packages:
cvs co -r V02-02-06 RecoVertex/AdaptiveVertexFinder cvs co -r V01-10-02 RecoBTag/SecondaryVertex
For a very low-level analysis (which is also partly outdated and therefore not recommended) need to check out two additional packages:
#cvs co -d IVF/BCandidateProducer UserCode/BbCorrelation/CMSSW/BAnalysis/BCandidateProducer #cvs co -d ZSV/BAnalysis UserCode/ZSV/BAnalysis/ #scram b -c
Last command needed to update really old IVF package config files to BuildFile.xml files.
Work flow
General vertexing
In order to get the IVF to work one has to perform inclusive vertexing by including inclusiveVertexing_cff.py:
process.load('RecoVertex/AdaptiveVertexFinder/inclusiveVertexing_cff')
The IVF runs on pre-selected vertices. After a coarse pre-clustering based on track distances and angles, vertices are reconstructed with the Adaptive fitter (outlier resistant, iterative procedure). This is done using the inclusive vertex finder from the adaptive vertex finder package:
- Source code: InclusiveVertexFinder.cc
- Configuration file: inclusiveVertexFinder_cfi.py
These vertices are then merged depending on their significance in distance and the fraction of tracks they share (in particular vertices with a large fraction of common tracks are merged):
- Source code: VertexMerger.cc
- Configuration file: vertexMerger_cfi.py
- using the standard config:
- maxFraction = 0.7
- minSignificance = 2
In the next step it is made sure that all tracks belong either to a secondary vertex or the primary vertex only optimising the assignment of tracks to vertices, followed by another vertex fit:
These refitted vertices are then again merged depending on their significance in distance and the fraction of tracks they share:
- Source code: VertexMerger.cc
- Configuration file: vertexMerger_cfi.py
- config is overwritten by inclusiveVertexing_cff.py to:
- maxFraction = 0.2
- minSignificance = 10
b-vertex filtering
The optimised vertices undergo a b-vertex filter:
- Source code: BVertexFilter.cc
- Configuration file: bVertexFilter_cfi.py
b to charm decay vertex merging
- Source code: BtoCharmDecayVertexMerger.cc
- Configuration file: bToCharmDecayVertexMerger_cfi.py
Useful links
partly used in VHbb ntuples:
Carlotta's code:
twiki documentation:
CMSSW:
Current errors
none
