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Update ON the Study of Subjet Multiplicity

Update ON the Study of Subjet Multiplicity at CMS 7TeV. Manuk Zubin Mehta , Manjit Kaur Panjab University, Chandigarh. Introduction

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Update ON the Study of Subjet Multiplicity

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  1. Update ON the Study of Subjet Multiplicity at CMS 7TeV Manuk Zubin Mehta , Manjit Kaur Panjab University, Chandigarh

  2. Introduction • The jet shape study could provide the tool for quark-gluon jets separation: • • The internal structure of a jet is expected to depend on the type of parton creating the jet (quark or gluon) and ET of the jet. • • the study of jet shapes can help to test the models of underlying events .

  3. SubJets *Subjets are defined by reapplying the KT algorithm, this time starting with a constituents of a jet. *Number of Subjets within the jet is the Subjet multiplicity M.

  4. Standard Event Selection For Data • Single Jet Trigger HLT_Jet30U • Scraping veto • Primary vertex: – >= 4 DOF – |z| < 15 cm • Working in CMSSW_3_8_4 With PAT 4

  5. Jet Selection Criteria • Selecting Di Jet (Leading in ET) • Jet Quality Criteria :: Loose Jet ID criteria • (EMF > 0.01, n 90 hits > 1, fHPD< 0.98) • |𝜟𝝓 – ℿ | < 1.0 • pT > 50 GeV • |y | < 3.00 • KT ,D=0.6 algorithm used

  6. Data Samples Runs 132440-141899 /JetMETTau/Run2010A-Sep17ReReco_v2/RECO Runs 141900-144114 /JetMET/Run2010A-Sep17ReReco_v2/RECO Runs 144115-149711 /Jet/Run2010B-PromptReco-v2/RECO MC Samples /QCD_Pt30/Spring10-START3X_V26_S09-v1/GEN-SIM-RECO /QCD_Pt30-herwig/Spring10-START3X_V26_S09-v1/GEN-SIM-RECO /QCD_Pt30-herwigjimmy/Spring10-START3X_V26_S09-v1/GEN-SIM-RECO

  7. Monte Carlo used: • Herwig++, • Pythia 6, • Herwig6+Jimmy • Herwig and Pythia use different hadronization model • Also using different Underlying Event models • (UE is used to tune MC generators to data and measured in transverse region)

  8. Standard kinematic comparison plots for 3pb -1

  9. Subjet Multiplicity

  10. Subjet Multiplicity in various rapidity bins

  11. Subjet Multiplicity in two different pT bins

  12. Gluon Jets

  13. Quark Jets

  14. Worked in the Pre-Assembly jobs for RPC at BARC • Gas Blocks and Thermo formable gas pipes. • Ground Cables • Twisted Pair Cables • Mylar sheet cutting Note: All the things has been prepared for 100 chambers

  15. Plan of the near future • We have started evaluating all associated systematic uncertainties . • Also evaluating multiple (prescaled) trigger streams. • Also Working on method to find quark and gluon fractions from data. • Documenting Analysis Note CMS AN AN-10-252. Comments and suggestions are welcome!

  16. Back Up Slide

  17. Subjet Definition • Using Kt Algorithm • For every object i, dii = pTi2 • For pair(i,j), dij = min (pTi2,pTj2)𝜟Rij2/D2 • Find dmin • For Subjets ::: dmin > dcut • dcut = ycut *pT2(jet) • where 0≤ycut≤1 • We have taken (resolution parameter )ycut = 10 -3 for our analysis. Ref::

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