Preliminary analysis of ZHH events (2) Michele Faucci Giannelli, Mike Green, Fabrizio Salvatore...
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Preliminary analysis of ZHH events (2)
Michele Faucci Giannelli,Mike Green, Fabrizio Salvatore
Royal Holloway, University of London
UK
CALICE UK-SOFTWARE meeting, 24/01/2006
06/12/2005 Michele Faucci Giannelli 2
UK
Outline
• Why using ZHH events ?
• Events Generation & Detector simulation
• Events Reconstruction
• New Status of ROOTProcessor
• New results for Z→e+e-, Z→+- channels
06/12/2005 Michele Faucci Giannelli 3
UK
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)
06/12/2005 Michele Faucci Giannelli 4
UK
• 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
Events Generation
06/12/2005 Michele Faucci Giannelli 5
UK
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
06/12/2005 Michele Faucci Giannelli 7
UK
Z→+- 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
06/12/2005 Michele Faucci Giannelli 8
UK
Z→+- 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 minimizeis used to calculate the Higgs mass
2h342
h122hh mmmmD
06/12/2005 Michele Faucci Giannelli 9
UK
Z→+- analysis
Some differences with the new cuts
The long tail will disappear later
Old New
06/12/2005 Michele Faucci Giannelli 10
UK
Z→+- analysis
Cut on D to eliminate the tails: D < XXX
Before After
06/12/2005 Michele Faucci Giannelli 13
UK
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
2h342
h122hh mmmmD
06/12/2005 Michele Faucci Giannelli 14
UK
Z→e+e- analysis
Differences with the new cuts
The long tail will disappear later
Old New
06/12/2005 Michele Faucci Giannelli 16
UK
Fit of Z→e+e-
Z H
Last Time
After jet requirement and D cut
06/12/2005 Michele Faucci Giannelli 17
UK
What has been done …
• New Processor in Marlin to produce an output in ROOT format is working fine
• Analysis of Z→+- and Z→e+e- using simple analysis, – mass plot are improved from December
• still to understand some problems (missing energy)
06/12/2005 Michele Faucci Giannelli 18
UK
… 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 ?