1. QCD Background… and the Resolution Saminder Dhaliwal August 30 th 2005

2. Resolution!!!! Z -> e- e+ aod’s Herwig and Jimmy Resolution as a function of Energy Resolution as a function of eta Formula: (Reconstructed E – True E) / (0.1)*(sqrt [True E])

3. Resolution at different Energy’s

4. RMS and Sigma Full range of E 40GeV < E < 70GeV 50GeV < E < 70GeV 70GeV < E < 150GeV E > 150GeV Entries353761684177630561612 RMS4.3492.1952.9015.6165.403 sigma1.3421.1181.2161.831.565

5. Resolution at different eta’s -2.5 < eta < -2.0-2.0 < eta < -1.5

6. -0.5 < eta < 0.0 -1.5 < eta < -1.0 -1.0 < eta < -0.5

7. 1.0 < eta < 1.5 0.0 < eta < 0.5 0.5 < eta < 1.0

8. Resolution at different eta’s 2.0 < eta < 2.51.5 < eta < 2.0

9. RMS (Black) and Sigma (Red) at eta

10. QCD background Full Production Background mimics Higgs -> TauTau signal  Two tag Jets  One Tau Jet and one electron Tau e- qqqq Higgs Begin by Filtering events to have a background with a Lead jet and Second jet with certain Pt requirements. As well as this we filter for a possible Taujet and electron.

11. Filter 1Filter 2Filter 3Filter 4 Lead Jet Pt 40304030 Second Jet Pt 20152015 eta gap3.5 3.0 Number of Electrons 49813 Filter Off 90 Filters: 50 000 events generated with each filter

12. Electron Pt: with and without filter Lead Jet Pt > 30GeV Second Jet Pt > 15GeV eta gap > 3.0 No Filter used

13. Jet Pt with and without filter Jet 2Jet 1 Jet 3 Jet 4 Black = Filter OFF Green = Hard Filter (ON) Red = Soft Filter (ON)

14. Jet Eta with and without filter Jet 1Jet 2 Jet 3 Jet 4 Black = Filter OFF Red = Filter ON

15. Delta Eta Black = Filter OFF Red = Filter ON

16. Full Production Filter that asks for Lead Jet Pt > 30GeV, Second Jet Pt > 15GeV and eta gap > 3.0 We have at least 10 000 events with filters generated daily (about 5% of events pass filter). About 40GB/day Expect about 52 electrons of which 4-5 have Pt>20GeV to be generated daily.

17. Results so far… Identifying electrons  “hasTrack” and Pt > 20GeV  egamma  isEM Minimizing background electrons, (while keeping optimum signal)  Isolation cut (etcone)  E/P restrictions

18. Identifying Electrons HasTrack  Cluster matched to track by: 1) eta and phi at origin of track are compared to eta and phi of cluster. Need 0.05 agreement in eta, 0.1 in phi and E/P < 4 2) Track extrapolated from cluster to origin, at each compartment deltaEta and deltaPhi are calculated. Required to be 0,025 and 0.05 respectively. Egamma  Differentiates between egamma object and soft electrons  Considers shape of cluster and requires certain energy thresholds

19. Identifying Electrons isEM  A selection tool that considers the following: ClusterEtaRange, ClusterHadronicLeakage, ClusterMiddleSampling, ClusterFirstSampling, TrackEtaRange,TrackHits A0, TrackMatchAndEoP, TrackTRT (not used now)  Stricter than egamma, looks closer at the shower shape and track to calorimeter tracking.

20. Identifying electrons: Pt hasTrack and Pt < 20GeV egammaisEM

21. Identifying electrons: eta hasTrack and Pt < 20GeV egamma isEM

22. Identifying Electrons No CutshasTrack & Pt > 20 GeV egammaisEM Number of electrons candidates 1.93646e+06 129223 20372264 % of original candidates 6.67317%1.05202%0.0136332% Number of e- matched to Truth 1.25796e+06 10970517025232 Fake Rate 53.9358% 17.7913%19.6593%13.7931%

23. Minimizing Background electrons First Reduction by Etcone < 10GeV Secondly: 1.8 < E/P < 1.4 Cut selection minimizes background whilst keeping signal efficiency as high as possible. etcone cutetcone and E/P cut

24. Minimizing Background hasTrack & Pt > 20GeV egammaisEM etcone < 10GeV etcone<10GeV& 1.8 < E/P < 1.4 Number of electron candidates 129223 20372264 9139 % of original candidates 6.67317%1.05202% 0.0136332%0.00469931%0.00201399% Number of e- matched to Truth 109705170252327935 Fake Rate 17.7913%19.6593%13.7931%15.1899%11.4286%