Displaced Dimuon High Level Trigger

Complete: 4

Trigger outline (preliminary)

  • events have to pass the L1 dimuon trigger
  • primary vertex is reconstructed
  • muon tracks are reconstructed using the L1 muons as seeds
  • two muon tracks are combined (to build e.g. a J/psi) and required to be within a certain mass range
  • The Kalman Vertex Fitter is applied on these two tracks
  • A cut is applied on the decay length singnificance, on the chiČ of the fit and on the opening angle of the two tracks

Usage for CMSSW_1_3_0_pre6

  • tcshell:
scramv1 project CMSSW CMSSW_1_3_0_pre6
cd CMSSW\_1\_3\_0\_pre6/src
eval `scramv1 run -csh`
project CMSSW
cvs co -r V00-03-04 RecoTracker/TkSeedGenerator
cd RecoTracker/TkSeedGenerator
scramv1 b
cd ../..
cvs co -r V00-00-29 HLTrigger/btau
cd HLTrigger/btau
scramv1 b
  • modify data/displacedmumu/PathBToJpsiToMumu.cff and test/hltBToJPsiToMumu.cfg

What can be modified?

in included package HLTDisplacedmumuFilter

  • minimal decay length significance (> 3)
  • maximal normalised Chi2 of the Kalman Vertex Fitter (< 10)
  • minimul cosine of the opening angle of the two muons (> 0.9)
in CandSelector
  • the transverse momentum of the muon (> 2.5GeV)

in CandCombiner
  • the invariant mass (2.95 < m < 3.25) and momentum of the mumu particle(> 4GeV)

  • use L1 muons as seeds: the have to be corrected for drift in magnetic field
  • this depends on charge which is not correctly assigned by L1 trigger


  • try to use L2 dimuon filter
  • this would eliminate L1 muon charge problem
  • might improve timing

Review Status

Editor/Reviewer Comments
LotteWilke - 26 Mar 2007 page author
JennyWilliams - 27 Mar 2007 edited to fit swguide general layout

Responsible: LotteWilke
Last reviewed by: Reviewer

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Topic revision: r3 - 2007-03-29 - unknown

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