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TeV Muons Status Report

TeV Muons Status Report. Dimitri Bourilkov University of Florida CMS PRS/  Meeting, June 7, 2005, CERN. Introduction. Goal of the study: understand quantitatively the physics of TeV muons - why (and to what extent) are they special

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TeV Muons Status Report

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  1. TeV Muons Status Report Dimitri Bourilkov University of Florida CMS PRS/ Meeting, June 7, 2005, CERN

  2. Introduction • Goal of the study: understand quantitatively the physics of TeV muons - why (and to what extent) are they special • At UF we have seven samples of Z’ -> μ+μ- with masses 0.2, 0.5, 1.0, 1.5, 3.0, 4.0, 5.0 TeV generated to study TeV muons and the mass resolution (41500 events) • CMKIN_4_0_0, OSCAR_3_6_3, ORCA_8_7_1 used to produce digis and DST; filter after CMKIN to retain only muons and Final State Radiation  TeV Muons

  3. Study of Material Effects • Collect energy deposits along the muon trajectories by matching objects in a rapidity-phi cone around the tracks • ECAL clusters: EGClus_E5x5 • Jets: JetIC5A_E (ECAL+HCAL deposits) TeV Muons

  4. Energy Loss in ECAL - Flat <p> = 2569 GeV <p> = 415 GeV TeV Muons

  5. Energy Loss in ECAL+HCAL – Slowly Rising <p> = 415 GeV <p> = 2569 GeV TeV Muons

  6. Energy Losses TeV Muons

  7. Muon Reconstruction • Compare info from different muon objects by reconstructing the Z’ mass in different ways • Start with the global muon reconstructor MuonGLB_… • Saw some problems: tried taking the muon momentum from MuonGLB_out, eta and phi at the vertex • Added the jet energy to the muon momentum to compensate for the energy loss TeV Muons

  8. Mass Resolution @ 500 GeV GLB GLB_out + JetCOR GLB_out TeV Muons

  9. Mass Resolution @ 5000 GeV GLB GLB_out + JetCOR GLB_out TeV Muons

  10. Comparison of Reconstructors TeV Muons

  11. Some Observations • The jet energy correction is overcorrecting the muon momenta – is this connected to the correction coming mostly from HCAL and from electromagnetic showers? • The global muon reconstructor is less performant for TeV muon momenta – is this coming from the tracker? Will be investigated next TeV Muons

  12. Outlook • Energy losses are flat with muon momentum in the ECAL, slowly rising in the HCAL; in first order their size depends on the material budget, only weakly on the muon momentum • The frequency of energy losses rises with muon momentum, so we have two competing effects: the losses occur more often, but their impact (as % of the muon energy) is going down • The global muon reconstructor shows problems for muon momenta >~ 1 TeV (are they coming from tracker?) • Here a combination of the muon momentum at the edge of the muon chambers with the angles at origin works better ?! • Adding the jet energy helps to some extent to cure the energy loss (actually overcorrecting the effect); the price to pay is a small deterioration of the mass resolution TeV Muons

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