1. Some D0 Meeting December 2003 Muon Isolation Update Ken Johns University of Arizona

2. Some D0 Meeting December 2003 Z, Zj, Zjj Data = “Signal”  Sample u Emily Z skim u Cuts  Good vertex  2 muons with P T > 15 GeV/c  1 isolated muon  Same vertex  Muon phi (highest P T ) – metphi < 165 degrees  Corrected MET < 15 GeV  75 < dimu mass < 105 GeV/c 2  0, 1, >1 jets with E T > 20 GeV u Look at distributions of the “other” muon

3. Some D0 Meeting December 2003 bb p13 Data = “Background”  Sample u Dimu p13 skim u Cuts  Good vertex  2 muons with P T > 6 GeV/c  // ΔR > 0.5 between the two muons  1 muon with an associated jet  Same vertex  Muon phi (highest P T ) – metphi < 165 degrees  Corrected MET < 15 GeV  0 < dimu mass < 70 GeV/c 2  >1 jets with E T > 20 GeV u Look at distributions of the “other” muon

4. Some D0 Meeting December 2003 bb rat efficiency = f(Ptmu)  Rat == Halo11 / Ptmu u Let Ptmu = 6, 10, 12, 15 GeV/c u Define Rat cut where background efficiency = 10%  6 GeV/c = 0.32  10 GeV/c = 0.30  12 GeV/c = 0.28  15 GeV/c = 0.25 u => Only slowly varying with Ptcut u => But other isolation variables change slightly with Ptmu cut as well (statistics?)

5. Some D0 Meeting December 2003 Signal Efficiency  Signal efficiency for 10% background (bb) efficiency u Use 12 GeV/c cut sample for bb background (more statistics than 15 GeV/c) u (Arbitrarily) set background efficiency to 10%  Halo11 efficiency for signal (@3.8) = 75%  Trkpt efficiency for signal (@2.0) = 50%  Rat efficiency for signal (@0.28) = 92%  dR efficiency for signal (@0.5) = 75% u Rat still in the running as isolation variable u Note dR inefficiency as well  n.b. previous efficiencies used Ptmu = 6 GeV/c to determine bb cut points

6. Some D0 Meeting December 2003 p14 Zjj Data-MC Isolation Comparison  Pick signal efficiency = 90%  Ask what cut value gives this efficiency u Here Ptmu cut = 15 GeV/c u Halo11  Data = 6.4, MC = 3 u Trkpt  Data = > 10, MC = 4 u Rat  Data = 0.35, MC = 0.1

7. Some D0 Meeting December 2003 Zjj Data – Halo 11

8. Some D0 Meeting December 2003 Zjj MC – Halo11

9. Some D0 Meeting December 2003 Zjj Data – Trkpt

10. Some D0 Meeting December 2003 Zjj MC– Trkpt

11. Some D0 Meeting December 2003 Zjj Data – Rat

12. Some D0 Meeting December 2003 Zjj MC – Rat