Wjets bkg. Estimation in WW analysis Jun Gao , Yanwen Liu, Emmanuel - PowerPoint PPT Presentation

Wjets bkg. Estimation in WW analysis Jun Gao , Yanwen Liu, Emmanuel Monnier U niversity of S cience and T echnology of C hina & C entre de P hysique des P articules de M arseille 6 March 2014 1

Introduction • W+jets background for WW analysis • Using fake factor method: – Control region : tight lepton + loose lepton(non-tight) – W+jet contribution := Control region * “fake factor”. • Fake factor definition : f= Numerator /Denominator numerator : tight lepton Denominator :loose lepton estimated using a jet-enriched sample. 6 March 2014 2

Main features/concerns 1) The change of triggers in WW analysis ee/mm : Now using di-lepton trigger em: Now using the OR of single lepton trigger and em trigger Trigger may already have requirement on the quality of leptons. Electron-fake is the main concern. 2) Sample dependence (dijet-Wjet) Also take into account the possible bias introduced by event selection specifically used in nominal analysis. 6 March 2014 3

Trigger 1) The choise of the trigger in fake factor study is related to the triggers used in nominal analysis 2) Triggers used in the Fake factor study • g20_etcut and g24_etcut 1)prescale 6.2 e-6 and 1.0 e-4 2) mainly for em(fake e+real muon) channel , will see later. 3) loose electron : fail medium • E22vh_loose1 1)Prescale 3.0e-3 2) for ee channel , di-electron trigger 3) loose electron : pass loose fail medium • Mu15 • 1) Prescale 3.0e-3 4

Lepton Definition : Electron Electron Numerator Denominator Pt, eta, Nhits 20 GeV, |eta|<2.47 , exclude [1.37,1.52],Nhits>=4 Author , object quality author = 1 or 3 , (el_OQ & 1446) == 0 <0.4 mm <3 <3 Etcone30/Et <0.16 <0.3 <0.28 Ptcone30/Et <0.12 (20<pt<25) <0.16 <0.16 (pt>25) <0.1 IsEM Very tight (likelihoodID) (See the text below) Fail Numerator selection For e22vh_loose1 . Pass Veryloose_eID or loosePP fail Medium_eID For g20/24_etcut, fail Medium_eID 6 March 2014 5

Lepton Definition : Muon Muon Numerator = tight lepton Denominator Pt, eta, ID track 20 GeV, |eta|<2.4 combined muon Author , object quality author = 6 <1 mm <3 Cut removed Etcone30/Et <0.20 && <0.014*pt-0.15 <0.25 if 20<pt<25 <0.18 if 20<pt<25 < 0.3 if pt>25 <0.30 if pt>25 Ptcone30/Et <0.15 && <0.01pt-0.105 removed <0.12 Fail Numerator selection 6 March 2014 6

Jet-enriched fake lepton selection • Lepton-jet overlap removal (compared with Wjets CR in the next slide) 1) tight electron/jet 2) jet/tight muon 3) loose muon/jet • Suppress W&Z contribution Veto events if any lepton if mT > 30GeV Veto events if in the Z-mass window |M(ll)-Mz|<13 GeV Veto events if MET_RefFinal>30 The remaining W&Z contribution is subtracted by MC estimation • f= Numerator /Denominator Numverator = N(tight, data) – N(tight, MC ) Denominator = N(loose,data) – N(loose , MC) 6 March 2014 7

• The OR stategy not exactly the same as jet-enriched CR. • The event selection requires jet- veto . The requirement of ‘0 jet’ also affected by OR 6 March 2014 8

Pt distribution ( g20(24)_etcut ) • Loose definition: !Medium • Tight electron : the contamination (mainly from Zee, Wenu) will be subtracted • More reliability on MC subtraction in High-pT bins 6 March 2014 9

Pt distribution ( e22vh_loose1 ) • Loose definition: pass loose fail medium • Tight: Zee, Wenu. • Dut to trigger, Pt arount 22 GeV shows fluctuation. 6 March 2014 10

• Central value of fake factor and the main systematics 6 March 2014 11

Central value (low/high eta bins) Top:g20(24)etcut mid: e22vh_loose1 bottom :mu15 6 March 2014 12

<mu> distribution derived from ATLAS Lumi calculator. Left: g20_etcut Middle:g24_etcut Right: e22vh_loose1 • g20_etcut , <mu> is mainly within [10,25] 6 March 2014 13

Left: g20(24)_etcut Right: e22vh_loose1 Pile Up Check fake factor with averageIntPerXing < 20 or >20 6 March 2014 14

Sample dependence 1)Fake factor is estimated in jet-enriched CR: i)Veto events if any lepton if mT > 30GeV ii)Veto events if in the Z-mass window |M(ll)-Mz|<13 GeV iii)veto events if MET_RefFinal>30 2) Compare dijetMC and Wjets MC When studying Wjets MC Not doing i) ii) iii) listed above. Use the truth information instead. 3) in order to truly estimate the difference between jet-enriched CR and Wjet CR. Wjets MC MET dependence We inverse the cut iii) . For Wjets MC 6 March 2014 15

Sample dependence(left : photon trigger Right:single electron trigger) Wjets MC: truth info + MET>30 For comparison Wjets MC: truth info + MET>30 + Wjet CR OR + N(goodjet)=0 For Wjets MC 1) Change the OR strategy in Fake factor CR to be the same as that in Wjets CR 2) Require jet-veto In this way two CRs becomes more similar. Wjets fake factor looks stable between two plots. 6 March 2014 16

• Wjets CR • Show Em channel as an example • Em trigger together with single lepton trigger is used 6 March 2014 17

For OF channel (either electron or muon is fake) Want to see which trigger is fired. which trigger is fired? me em ( muon is fake) (electron is fake ) Case 1 em trigger only none 1.5% Case 2 electron trigger only 40% 3.8% Case 3 muon trigger only <1% 54% Case 4 em + electron only 60% 5.3% Case 5 em + muon only none 10.7% Case 6 electron + muon only none 3.1% Case 7 em+electron+muon (all triggers passed) none 21% Derived from W+jet MC. In most cases ( Red cells in the table. ~100% for me, ~90% for em) we rely on the tight lepton to fire trigger. Choose the fake factor wisely. E.g. In em channel , if the tight muon not firing the trigger while the em trigger is fired, we will use fake factor from e22vh_medium1 6 March 2014 18

W+jet control region em(electron is fake) channel tight pt loose pt tight eta loose eta 6 March 2014 19

W+jet control region me(muon is fake) channel tight pt loose pt tight eta loose eta 6 March 2014 20

results In W+jets CR, the total background is the sum of estimation from data and subtraction of non- W+jets contributions predicted from MC Summary ee mm em (fake e+m & fake m +e) Data-driven result 42.1 +/- 11.8 +/- 24.1 13.8 +/- 5.9 +/- 6.9 147.8 +/-5.6 +/- 78.2 Now comparing results with other mothod 6 March 2014 21

• Back-up 6 March 2014 22

MC used • Wz inclusive • mc12_8TeV.147800.PowhegPythia8_AU2CT10_Wplusenu.merge.NTUP_SMWZ.e1169_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147801.PowhegPythia8_AU2CT10_Wplusmunu.merge.NTUP_SMWZ.e1169_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147802.PowhegPythia8_AU2CT10_Wplustaunu.merge.NTUP_SMWZ.e1169_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147803.PowhegPythia8_AU2CT10_Wminenu.merge.NTUP_SMWZ.e1169_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147804.PowhegPythia8_AU2CT10_Wminmunu.merge.NTUP_SMWZ.e1169_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147805.PowhegPythia8_AU2CT10_Wmintaunu.merge.NTUP_SMWZ.e1169_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147806.PowhegPythia8_AU2CT10_Zee.merge.NTUP_SMWZ.e1169_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147807.PowhegPythia8_AU2CT10_Zmumu.merge.NTUP_SMWZ.e1169_s1469_s1470_r3752_r3549_p1328/ • mc12_8TeV.147808.PowhegPythia8_AU2CT10_Ztautau.merge.NTUP_SMWZ.e1169_s1469_s1470_r3542_r3549_p1328/ DY Low Mass samples included Di-jet MC • MUON • mc12_8TeV.147910.Pythia8_AU2CT10_jetjet_JZ0W.merge.NTUP_SMWZ.e1126_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147911.Pythia8_AU2CT10_jetjet_JZ1W.merge.NTUP_SMWZ.e1126_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147912.Pythia8_AU2CT10_jetjet_JZ2W.merge.NTUP_SMWZ.e1126_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147913.Pythia8_AU2CT10_jetjet_JZ3W.merge.NTUP_SMWZ.e1126_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147914.Pythia8_AU2CT10_jetjet_JZ4W.merge.NTUP_SMWZ.e1126_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147915.Pythia8_AU2CT10_jetjet_JZ5W.merge.NTUP_SMWZ.e1126_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147916.Pythia8_AU2CT10_jetjet_JZ6W.merge.NTUP_SMWZ.e1126_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.147917.Pythia8_AU2CT10_jetjet_JZ7W.merge.NTUP_SMWZ.e1126_s1469_s1470_r3542_r3549_p1328/ • mc12_8TeV.129390.Pythia8_AU2CT10_jetjet_JZ0W_mufilter.merge.NTUP_SMWZ.e1318_s1499_s1504_r3730_r3549_p1328/ • mc12_8TeV.129391.Pythia8_AU2CT10_jetjet_JZ1W_mufilter.merge.NTUP_SMWZ.e1318_s1499_s1504_r3730_r3549_p1328/ • mc12_8TeV.129392.Pythia8_AU2CT10_jetjet_JZ2W_mufilter.merge.NTUP_SMWZ.e1318_s1499_s1504_r3730_r3549_p1328/ • mc12_8TeV.129393.Pythia8_AU2CT10_jetjet_JZ3W_mufilter.merge.NTUP_SMWZ.e1318_s1499_s1504_r3730_r3549_p1328/ • ELECTRON • mc12_8TeV.129160.Pythia8_AU2CTEQ6L1_perf_JF17.merge.NTUP_SMWZ.e1130_s1468_s1470_r3542_r3549_p1328/ 6 March 2014 23