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A (very) preliminary study of channel pp->h->ZZ->4mu via gg fusion with CMSSW

A (very) preliminary study of channel pp->h->ZZ->4mu via gg fusion with CMSSW. Alessandro Giacobbe Cristina Botta Daniele Trocino. Relatrice: Chiara Mariotti. Signal. gg → h → ZZ→ 4mu. Leading Order Feynman Diagrams. Torino, 27/03/2007. Backgrounds. ZZ( ) → 4mu. Leading

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A (very) preliminary study of channel pp->h->ZZ->4mu via gg fusion with CMSSW

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  1. A (very) preliminary study of channel pp->h->ZZ->4mu via gg fusion with CMSSW Alessandro Giacobbe Cristina Botta Daniele Trocino Relatrice: Chiara Mariotti

  2. Signal gg → h → ZZ→ 4mu Leading Order Feynman Diagrams Torino, 27/03/2007

  3. Backgrounds • ZZ( ) → 4mu Leading Order Feynman Diagrams • Zbb → 4mu • tt → 4mu Torino, 27/03/2007

  4. Pythia: MC Generation of events • gg → h → ZZ → 4mu • ZZ → 4mu • Zbb → 4mu • tt → 4mu (more events for a better study of the signal) (as we still don’t have more events generated by Comphep) We work with the expected Luminosity of the first 2 years : Torino, 27/03/2007

  5. CMSSW: what we need to know • The overall software, called CMSSW, is build around a Framework, an Event Data Model (EDM) and services need by the modules that process data • Only one executable : cmsRun • Many plug-in modules run algorithms: the same for detector and MC data *.CFG MODULE • used to configure cmsRun at run time • tells which data to use • modules to run (all loaded at beginning of the job) • parameters to set • component of CMSSW code • can be plugged into cmsRun • it is called for every Event according to the path statement • 6 differet types (Source,EDProducer, EDFilter, EDAnalyzer, EDLooper, OutpuModule) • configured through *.cfg using modul-specific ParameterSets Torino, 27/03/2007

  6. CMSSW: how it works • Events are processed by passing the event through a sequence of modules • the module can get data from the Event and put data back to the Event (not every module) • each module can “talk” to the others only through the Event Torino, 27/03/2007

  7. The FourMuFilter A Filter is a module that we used to apply cuts in generation. To be accepted the event must have in the final state: at least 4 mu, 2 positive and 2 negative, with Pt > 3 GeV, |η| < 2.5. Warning: If the Event doesn’t satisfy the condition it won’t be automatically rejected. To have in output only filtered events you need to specify it in the PooloutModule. Torino, 27/03/2007

  8. The FourMuFilter(2) • gg → h → ZZ → 4mu • ZZ( )→ 4mu • Zbb → 4mu • tt → 4mu GeV • In the next days our filter will be send to Filip Moortgat in order to include it in the next MC production Torino, 27/03/2007

  9. Pythia kinematic cuts (1) Apart from standard settings that we include in the list of pythia cards ( such as the choice of the partonic functions, or the swich on of parton shower and QED bremsstrahlung), we also introduce the following Kinematics cuts (that behave like a pythia inner filter) : • CKIN(45) - CKIN(48) : (D = 12., -1, 12., -1) • range of allowed mass values of the two secondary resonances • produced in a 2->1->2 process like gg->h->ZZ • CKIN(41) - CKIN(44) : (D = 12., -1, 12., -1) • range of allowed mass values of the primary resonances Torino, 27/03/2007

  10. Pythia kinematic cuts (3) Cuts set at 5.,150.,5.,150. Default Kinematics Cuts The situation is the same. We chosed to let this setting as it seems to be the standard way. GeV Torino, 27/03/2007

  11. Pythia kinematic cuts (2) Cuts set at 5.,150.,5.,150. Default Kinematics Cuts Useless generated events. We will surely cut this peack coming from μ generated by virtual photons. GeV Torino, 27/03/2007

  12. Analysis of the generated variables: the FourMuAnalyzer • Invariant Mass: • all possible muons pairs • muons pairs coming from Z → lower values of • (in this way we selected candidate Z) • ZZ pairs • Transverse Momentum: • pt of all muons • max, second, third, min pt of muons • pt of all Z • Angular Variables: • pseudorapidity of muons and Z • theta between two muons with same charge • theta between two muons from Z • Theta between two candidate Z Torino, 27/03/2007

  13. Plots: Normalized and Weighted Generated Variables of Signal ( ) and Background Transverse Momentum Torino, 27/03/2007

  14. Plots: Normalized and Weighted Generated Variables of Signal ( ) and Background Torino, 27/03/2007

  15. Plots: Normalized and Weighted Generated Variables of Signal ( ) and Background Torino, 27/03/2007

  16. Plots: Normalized and Weighted Generated Variables of Signal ( ) and Background Invariant Mass Torino, 27/03/2007

  17. Plots: Normalized and Weighted Generated Variables of Signal ( ) and Background Torino, 27/03/2007

  18. Plots: Normalized and Weighted Generated Variables of Signal ( ) and Background Angular Variables Torino, 27/03/2007

  19. Plots: Normalized and Weighted Torino, 27/03/2007

  20. How well do we “reconstruct” Z’s? The FourMuTruth Z candidates ↔ μ+μ- couples nearest to Z mass To measure how much this method works, we define two efficiencies: Pythia provides history of each generated event (production/decay chain) → it’s possible to verify how often μ-couples really come from a generated Z We get: for both h → ZZ → 4μ and ZZ → 4μ processes Main inefficiency cause: photons emission in final state Torino, 19/03/2007

  21. How well do we “reconstruct” Z’s? The FourMuTruth Pythia also provides information about all generated particles (E, p, η …) → it’s possible to access “true” data (i.e. generated with MC) and compare them to “reconstructed” data (i.e. from selected μ-couples) Torino, 19/03/2007

  22. Higgs produced via VV Fusion • VV → h → ZZ → 4mu • Aims: • compare Pythia-Phantom for VV-fusion • (attempt to) separate VV-fusion signal • from gg-fusion one Torino, 19/03/2007

  23. Weighted plots: expected events Generated variables of signal gg-fusion, signal VV-fusion, background Torino, 19/03/2007

  24. Kinematics differences Generated variables of signal gg-fusion, signal VV-fusion, background Normalized plots Torino, 19/03/2007

  25. Kinematics differences Generated variables of signal gg-fusion, signal VV-fusion, background Normalized plots Torino, 19/03/2007

  26. Kinematics differences Generated variables of signal gg-fusion, signal VV-fusion, background Normalized plots Torino, 19/03/2007

  27. What to do: First of all… EXAMS !!!!!!!! Apply cuts: muons Pt muons pairs invariant mass (Z cand. mass) find new kinematics variables (muons collinearity, …) Do the same study for final state: Do the complete simulation- Reconstruction: SIMU-DIGI-RECO Torino, 19/03/2007

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