Efficiency of Muon Reconstruction July 23,2007 Jongseok Lee, Suyong Choi (Sungkyunkwan University)

Introduction For more details about analysis see Suyong's talk in Muon POG of June 19: http://indico.cern.ch/conferenceDisplay.py?confId=17335 Based on Drell-Yan muon sample from CMSSW131: CMSSW_1_3_1-Spring07-1349/GEN-SIM-DIGI-RECO No backgrounds (yet) Question: how does efficiency obtained with tag-and-probe compare to efficiency from MC Truth?

decay mode : Z -> μ+μ- (mc data) stand alone muon : reconstructed muon by muon detectors track : reconstructed muon by tracker global muon : reconstructed muon by tracker + muon detectors

Steps for tag-and-probe 1.Choose a high momentum global muon (pt>10GeV) 2.Look for another high momentum track from the global muon (typically ΔΦ>1.5) 3.Form invariant mass of global muon + track (red) 4.Form invariant mass of global muon + matched track with opposite global muon (green, matching cut ΔR<0.01)

Efficiencies from tag-and-probe method pt(μ)>15, ΔΦ(μ μ)>1.5, 70<mass(μμ)<110 pt(μ)>15, ΔΦ(μ μ)>0.5, no masscut

Steps for mc-truth 1.Choose a mc muon (|η|<2.4) 2.Look for a matched track with the mc muon (matching cut ΔR<0.01) 3.Repeat 1~2 for the opposite mc muon 3.Form invariant mass of mc muon + opposite mc muon (red) 4.Form invariant mass of mc muon + matched track with opposite global muon (green, matching cut ΔR<0.01)

Efficiencies from mc-truth method cut for mc truth μ |η|<2.4 cut for matching ΔR<0.01 (ΔR = sqrt(Δθ2+ΔΦ2))

Isolation ΔR = sqrt(Δθ2+ΔΦ2) : isolation angle isolation energy = sum energy of particles near the μ  cut for jet (1GeV) μ ΔR<0.5 jet μ a2 a4 a3 a1 GeV isolated

Efficiencies from tag-and-probe method ΔR<0.1 ΔR<0.2 ΔR<0.3 ΔR<0.4 ΔR<0.5 Cut : pt(μ)>10GeV no masscut ΔΦ(μ μ)>0.5 isolationE 1GeV

Distribution of mass(μμ), pt and η tag-and-probe method(ΔR<0.5) mc-truth method(|η|<2.4)

Efficiencies overlay of tag&probe and mc-truth Cut of tag-and-probe method: pt(μ)>10GeV no masscut ΔΦ(μ μ)>0.5 ΔR<0.5 (isolation) isolationE 1GeV Cut of mc-truth method: |η|<2.4 ΔR<0.01 (matching) average efficiency of pt: 0.975±0.000991 (tag-and-probe) 0.971±0.000692 (mc-truth) average efficiency of η: 0.975±0.000991 (tag-and-probe) 0.971±0.000692 (mc-truth)

Efficiencies with Fits tag&probe method(ΔR<0.5) mc-truth method

Conclusion Average Tag-and-probe and MC Truth agree better than 1% More study needed to understand sub-1% differences, and dependence vs eta and pT Next steps: - look at other components of the efficiency (e.g. trigger) - add realistic background - develop a complete analysis strategy

Back up

Entries comparison # of all mc-truth muon(no cut ) = 7000 # of all global muon (no cut) = 8069 isolation energy of global muon isolation energy of track muon ΔR<0.5 ΔR<0.5 GeV GeV