A measurement of the Ratio of Three over Two Jet Cross Sections with CMS at 7TeV 70 nb -1 P.Kokkas, I.Papadopoulos, C.Fountas, I.Evangelou, N.Manthos University of Ioannina, Greece Senior Editor for PAS : James Rohlf Boston University, USA

Data Analysis Data Samples (Runs ) : /MinimumBias/Commissioning10-SD_JetMETTau-Jun14thSkim_v1/RECO (Runs ) : /JetMETTau/Run2010A-Jun14thReReco_v2/RECO (Runs ) : /JetMETTau/Run2010A-PromptReco-v4/RECO CMS official JSON files: Cert_ _7TeV_June14thReReco_Collisions10_JSON.txt Cert_ _7TeV_StreamExpress_Collisions10_JSON.txt Total Integ.Lumi = 76 nb -1 (Evaluated from crab) MC Samples PYTHIA: QCDDiJet_Ptxxtoxx/Spring10-START3X_V26_S09-v1/GEN-SIM-RECO Madgraph: QCD_Ptxxtoxx-madgraph/Spring10-START3X_V26_S09-v1/GEN-SIM-RECO 2 On line Selection: Require BPTX Technical bit 0, to select events with consistent timing with LHC bunch crossing Select events with HLT Jet30U P.Kokkas, Univ. of Ioannina

Trigger Studies P.Kokkas, Univ. of Ioannina3 Runs Runs HLT Jet TriggerL1 PrerequisitePrescaled HLT Jet15UL1 SingleJet6UYes (for Runs> ) HLT Jet30UL1 SingleJet20Uno HLT Jet50UL1 SingleJet30Uno Main HLT Jet Triggers HLT Jet TriggerTurn on points (GeV) Leading Jet HLT Jet30U62 HLT Jet50U87 Trigger efficiencies: Complete agreement of new sample (Runs>138564) with the old sample (Runs<137028)

Trigger HT2 P.Kokkas, Univ. of Ioannina4 Runs Runs Runs Runs HLT Jet Trigger H T nJets≥2 (GeV) H T nJets≥3 (GeV) HLT Jet30U HLT Jet50U230 Since we plot R 32 above 200 GeV trigger HLT Jet30U is fully efficient.

Data Stability 5 nJets≥2 Plot does not take into account error of Luminocity. Runs , , , , and are some sigmas away. Correspond to 9.5 nb -1.

Data Stability P.Kokkas, Univ. of Ioannina6 nJets≥3

Data Stability P.Kokkas, Univ. of Ioannina7

Data Stability Good runs P.Kokkas, Univ. of Ioannina8 nJets≥2

Data Stability Good runs P.Kokkas, Univ. of Ioannina9 nJets≥3

Data Stability Good runs P.Kokkas, Univ. of Ioannina10

Off Line selection P.Kokkas, Univ. of Ioannina11 Off line Selection: Primary Vertex: |PVz| 4 Jet selection: p T ≥ 50 GeV and |y|≤2.5 “Loose” Jet ID : EMF > 0.01 OR |η|>2.6, n90Hits > 1, FHPD < 0.98 SelectionEvents 76nb -1 Events 66.5nb -1 AfterTrigger, Data quality &PV p T ≥50GeV, |y|≤2.5 & ‘’Loose” JetID At least 2 jets At least 3 jets

76nb -1 P.Kokkas, Univ. of Ioannina12 76 nb -1

Data over PYTHIA : All Jets 13

Data over PYTHIA : Leading Jets 14 PYTHIA MC normalized to the total number of inclusive DiJet events.

Data over Madgraph : All Jets 15

Data over Madgraph : Leading Jets 16 Madgraph MC normalized to the total number of inclusive DiJet events.

NJets P.Kokkas, Univ. of Ioannina17 PYTHIA and Madgraph MC normalized to the total number of inclusive DiJet events.

Data over MC 18

R 32 at calo Level P.Kokkas, Univ. of Ioannina19 AxB Pythia

66.5 nb -1 P.Kokkas, Univ. of Ioannina nb -1

Data over PYTHIA : All Jets 21

Data over PYTHIA : Leading Jets 22 PYTHIA MC normalized to the total number of inclusive DiJet events.

Data over Madgraph : All Jets 23

Data over Madgraph : Leading Jets 24 Madgraph MC normalized to the total number of inclusive DiJet events.

Njets 25 PYTHIA and Madgraph MC normalized to the total number of inclusive DiJet events.

Data over MC 26

R 32 at calo Level P.Kokkas, Univ. of Ioannina27 AxB Pythia

Final Result P.Kokkas, Univ. of Ioannina28 Final Result

R32 at Hadron Level 76nb P.Kokkas, Univ. of Ioannina29

R 32 at Hadron Level 66.5 nb -1 P.Kokkas, Univ. of Ioannina30

Spare P.Kokkas, Univ. of Ioannina31

Data Stability statistics 32

Data Stability statistics 33

R32 P.Kokkas, Univ. of Ioannina34

PT Ratios old-new P.Kokkas, Univ. of Ioannina35

P.Kokkas, Univ. of Ioannina36

Data over PYTHIA : all Jets HT>200 37

Data over PYTHIA : Leading Jets HT>200 38

Data over Madgraph : all Jets HT>200 39

Data over PYTHIA : Leading Jets HT>200 40

nJets HT>200 P.Kokkas, Univ. of Ioannina41