Refitting tracks with TwoBodyDecay constraints

Introduction

Description of the TwoBodyDecay algorithm

Installation of the package

The available recipes

There is a python 'cff' file dedicated to each kind of constraint.

• 'TwoBodyDecayVertexConstraintProducer_cff.py' for vertex constraint
• 'TwoBodyDecayMomentumConstraintProducer_cff.py' for momentum constraint
• 'TwoBodyDecayConstraintProducer_cff.py' for trajectory state constraint

The module sequences of these files are based on the same sketch :

• selecting the tracks with a TrackSelector
• refitting the tracks according to the alignment and calibration configuration
• constructing a constraint with TwoBodyDecay from the selected tracks
• refitting the selected track with the produced constraint

To uses these files, you have just to include in your main python script le following lines (example in the case of the momentum constraint) :

process.load("refitter.TwoBodyDecayMomentumConstraintProducer_cff.py")
AlignmentTrackSelector.src = cms.InputTag( "generalTracks" )

The first line allows to call the correct 'cff' file ; the second one to specify the origin the source of the tracks (by default 'generalTracks'). The sequence returns a collection of 'reco::Track' with the tag 'TrackRefitterTBDFullConstraint'.

Advanced use : change recipe settings

Track selection

TwoBodyDecay

Several parts in the configuration.

• input for TwoBodyDecay fit

• internal parameter to the TwoBodyDecay fit

• cut

-- EricConte - 14-Feb-2012