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

UK 06/12/2005Michele Faucci Giannelli2 Outline Why using ZHH events ? Events Generation & Detector simulation Events Reconstruction New Status of ROOTProcessor New results for Z→e + e -, Z→  +  - channels

UK 06/12/2005Michele Faucci Giannelli3 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)

UK 06/12/2005Michele Faucci Giannelli4 Use Pandora Pythia: –M(Higgs)=120 GeV & E CM = 500 GeV Used Mokka (V05-03) –detector model: D10scint Using MARLIN (V09-01) –Using Durham jet finding algorithm –Root output Events Generation

UK 06/12/2005Michele Faucci Giannelli5 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

UK 06/12/2005Michele Faucci Giannelli6 Z→  +  - analysis Missing energy !!

UK 06/12/2005Michele Faucci Giannelli7 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) E t <380 GeV E t >380 GeV

UK 06/12/2005Michele Faucci Giannelli8 Z→  +  - analysis Two request: –E tot > 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

UK 06/12/2005Michele Faucci Giannelli9 Z→  +  - analysis Some differences with the new cuts The long tail will disappear later OldNew

UK 06/12/2005Michele Faucci Giannelli10 Z→  +  - analysis Cut on D to eliminate the tails: D < XXX BeforeAfter

UK 06/12/2005Michele Faucci Giannelli11 Fit of Z→  +  - Z H Last Time After jet requirement and D cut

UK 06/12/2005Michele Faucci Giannelli12 Z→e + e - analysis No missing energy

UK 06/12/2005Michele Faucci Giannelli13 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 i s used to calculate the Higgs mass

UK 06/12/2005Michele Faucci Giannelli14 Z→e + e - analysis Differences with the new cuts The long tail will disappear later OldNew

UK 06/12/2005Michele Faucci Giannelli15 Z→e + e - analysis D < XXX BeforeAfter

UK 06/12/2005Michele Faucci Giannelli16 Fit of Z→e + e - Z H Last Time After jet requirement and D cut

UK 06/12/2005Michele Faucci Giannelli17 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)

UK 06/12/2005Michele Faucci Giannelli18 … 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 ?