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University of Iowa

University of Iowa. Status qq->H->zz with fully simulated calorimeters Alexi Mestvirishvili FIU Feb. 2004. Event generation and reconstruction. PYTHIA 6.2, CMSIM version 127, ORCA version 7.3.0, ROOTMAKER Initial and Final state radiations are switched on

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University of Iowa

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  1. University of Iowa Status qq->H->zz with fully simulated calorimeters Alexi Mestvirishvili FIU Feb. 2004

  2. Event generation and reconstruction PYTHIA 6.2, CMSIM version 127, ORCA version 7.3.0, ROOTMAKER Initial and Final state radiations are switched on No Pileup (for the time being) No tracker was simulated, particle level analysis was done on the generator particles. This concerns mainly Z  e+ e- reconstruction.

  3. Event samples Signal events qqH (Pythia proc. 124 (WW fusion)) 300, 350 and 500 GeV was considered as H mass Background events Direct ZZ production (Pythia proc.22) WWZZ (Pythia proc.76) One of Z decays to e+ e-, anotherZ to neutrinos, thus generating large missing ET Additional background -- ttbar events where each t quark decays to Wb and each W decays to two leptons (e+/e-) . Central jets veto was not used due to the ISR and FSR switched on. Z+jets was not simulated. Preliminary analysis with CMSJET shows total negligence of this kind of background.

  4. Jets pre selection Jets in the cone 0.5 rec. with iterative algorithm were used. Jets with ET 20GeV must be well within CMS acceptance ||  5. Any jet closely associated to the leptons were removed from the jet list. Jet isolation condition:- no any object around the jet in the cone with R=0.5 H M(300GeV) H M(350GeV) H M(500GeV) ZZ WW->ZZ ttbar Multiplicity Pseudorapidity

  5. Tag jets selection |j1-j2|>4; j1· j2 < 0; Tag jets pair combinations H M(300GeV) H M(350GeV) % H M(500GeV) ZZ WW->ZZ ttbar Jet pair comb.

  6. Tag jets selection H M(300GeV) H M(350GeV) Tag jets Pseudorapidity H M(500GeV) ZZ WW->ZZ ttbar Pseudorapidity.

  7. ? ontag jets selection Restriction on ET20GeV cuts out 17 % of events with pair of forward jets ET Cut value Red arrows indicate forward region occupied with the high energetic jets and ET<20GeV Blue arrow – central region With low energetic jets and ET<20GeV. May be better cut On E rather tan on ET?

  8. Lepton Selection and cut on Missing ET Leptons (e+ e- ) were selected from generator particles data. Lepton cuts: ||<2.5, ET > 20GeV, |M(e+ e-)-M(Z)|<15GeV, j,min +0.5< l< j,max-0.5 (Leptons are between tag jets) Requirement for reconstructed Missing ET > 50GeV This cut along with others totally eliminates Z+jets events

  9. Number of Events, CS, Integrated luminosity *-- statistic needs to be increased

  10. Acceptance for individual process after all the cuts *-- Since tracker was not simulated and b jet tagging wasn’t used, all the events with the tag jets in the region covered by tracker were dropped. This assumes 100% efficient B jet vetoing.

  11. Number of events

  12. Significance and LHC luminosity again 5 significance level 100fb-1 60fb-1

  13. Conclusions • Even WW  ZZ has very same topology as signal events, their contribution to the background is almost negligible due to the small CS. • Main background comes from direct ZZ and t tbar because of huge production CS. • Even WBF processes has second largest CS after Higgs gg production scheme, it will be necessary few years of running to observe H produced in WW fusion and decayed to this particular channel.

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