1. Update ON the Study of Subjet Multiplicity at CMS 7TeV Manuk Zubin Mehta, Manjit Kaur Panjab University, Chandigarh 11/27/2015 1

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 E T of the jet. the study of jet shapes can help to test the models of underlying events. 2

3. SubJets *Subjets are defined by reapplying the K T algorithm, this time starting with a constituents of a jet. *Number of Subjets within the jet is the Subjet multiplicity M. 11/27/2015 3

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 11/27/2015 4

5. Jet Selection Criteria Selecting Di Jet (Leading in E T ) Jet Quality Criteria :: Loose Jet ID criteria (EMF > 0.01, n 90 hits > 1, f HPD < 0.98) | – ℿ | < 1.0 p T > 50 GeV |y | < 3.00 K T,D=0.6 algorithm used 11/27/2015 5

6. Data Samples 11/27/2015 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 6

7. 11/27/2015 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) 7

8. 11/27/2015 Standard kinematic comparison plots for 3pb -1 8

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10. Subjet Multiplicity 10

11. 11/27/2015 Subjet Multiplicity in various rapidity bins 11

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13. 11/27/2015 Subjet Multiplicity in two different p T bins 13

14. 11/27/2015 Gluon Jets 14

15. 11/27/2015 Quark Jets 15

16. 11/27/2015 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 16

17. 11/27/2015 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! 17

18. 11/27/2015 Back Up Slide 18

19. 11/27/2015 Subjet Definition Using K t Algorithm For every object i, d ii = p Ti 2 For pair(i,j), d ij = min (p Ti 2,p Tj 2 )R ij 2 /D 2 Find d min For Subjets ::: d min > d cut d cut = y cut *p T 2 (jet) where 0≤y cut ≤1 We have taken (resolution parameter )y cut = 10 -3 for our analysis. Ref:: 19

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