Preliminary analysis of ZHH events (2)

1. Calice UK Preliminary analysis of ZHH events (2) Michele Faucci Giannelli, Mike Green, Fabrizio Salvatore Royal Holloway, University of London CALICE UK-SOFTWARE meeting, 24/01/2006

2. Outline • Why using ZHH events ? • Events Generation & Detector simulation • Events Reconstruction • New Status of ROOTProcessor • New results for Z→e+e-, Z→m+m- channels Michele Faucci Giannelli

3. Why ZHH events ? • Study of Higgs self coupling constant • These events can also be used as benchmark events for several detector/PFlow studies: • ECAL & HCAL performances, • Jet-finding algorithms, • b-tagging, • tracker, etc... see: M.Battaglia et al, “Physics Benchmarks for the ILC Detectors” (2005 ILC Workshop, Stanford, USA) Michele Faucci Giannelli

4. Events Generation • Use Pandora Pythia: • M(Higgs)=120 GeV & ECM = 500 GeV • Used Mokka (V05-03) • detector model: D10scint • Using MARLIN (V09-01) • Using Durham jet finding algorithm • Root output Michele Faucci Giannelli

5. Status of ROOTProcessor • All information of ReconstructedParticle Class for PFlow and ReconstructedParticle Collections stored in a ROOT file • Added the truth (MCParticle Class) of MCParticle collection • Note: difficult to compare MC and Reco event-by-event Michele Faucci Giannelli

6. Z→m+m- analysis Missing energy !! Michele Faucci Giannelli

7. Z→m+m- analysis • In order to understand the problem I looked at the number of particle in the “jet”. There are no muon in the low energy events (problem with muon id? Need to investigate) Et<380 GeV Et>380 GeV Michele Faucci Giannelli

8. Z→m+m- analysis • Two request: • Etot > 380 GeV • At least 2 “jets” must have less than 7 particle, those are identified as muons • The remaining 4 jets are combined in all 3 possible ways, the combination that minimize is used to calculate the Higgs mass Michele Faucci Giannelli

9. Some differences with the new cuts Z→m+m- analysis Old New The long tail will disappear later Michele Faucci Giannelli

10. Cut on D to eliminate the tails: D < XXX Z→m+m- analysis Before After Michele Faucci Giannelli

11. Fit of Z→m+m- After jet requirement and D cut Last Time Z H Michele Faucci Giannelli

12. Z→e+e-analysis No missing energy Michele Faucci Giannelli

13. Z→e+e-analysis • Only one request: • At least 2 “jets” must have less than 7 particle, those are identified as positron-electron pairs • The remaining 4 jets are combined in all 3 possible ways • the combination that minimize is used to calculate the Higgs mass Michele Faucci Giannelli

14. Differences with the new cuts Z→e+e-analysis Old New The long tail will disappear later Michele Faucci Giannelli

15. D < XXX Z→e+e-analysis Before After Michele Faucci Giannelli

16. Fit of Z→e+e- After jet requirement and D cut Last Time Z H Michele Faucci Giannelli

17. What has been done … • New Processor in Marlin to produce an output in ROOT format is working fine • Analysis of Z→m+m- and Z→e+e- using simple analysis, • mass plot are improved from December • still to understand some problems (missing energy) Michele Faucci Giannelli

18. … and what has still to be done • Study the MCParticle, now in ROOT-tuple • Study other variables • Implement the muon reconstruction in Marlin, before jet-finding algorithm • Understand the missing energy on muon events (using MC too) • Reconstruct same events using different detector models • e.g. D09 – need to sort out calibration • D10scint with reduced size (see H. Videau’s talk at Vienna) • Analyze events using different PF algorithms • Mark’s new PF ? • Chris/George’s new clustering ? Michele Faucci Giannelli