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Top Cross Section Measurement

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Top Cross Section Measurement

  1. 1. Top Quarks in Year 1 Akira Shibata New York University ATLAS Workshop of the Americas @ NYU 5 Aug, 2009
  2. 2. Can Top change our perspective? • Why is top so heavy (10 water molecules)? Any special role in EW symmetry breaking? • Does it play even more fundamental role than Higgs mechanism + Yukawa coupling? • If there is new physics signal lighter than top, does the top quark decay into them? • Could non-SM physics first manifest itself in non- standard couplings of the top quark? • Top quark can be measured at significant precision at the LHC to answer these questions. • Top quark has been an extremely productive ground for speculation and searches at Tevatron. Workshop of the Americas ’09 2 akira.shibata@nyu.edu
  3. 3. New Physics via Top Decay • The final state of a t¯system is primarily clas- t sified by the decay modes of the two W bosons: • Various decay modes make top physics interesting and useful • The top interfere with a number of new physics signatures. • Typical search modes: • Lepton + jets (e/mu) • Dileptonic • All hadronic • Tau channels • E.g. If mW<mH+<mt and tanβ>>1, top can decay into charged higgs, enhancing the τ lepton rate. Workshop of the Americas ’09 3 akira.shibata@nyu.edu
  4. 4. New Physics via Top Decay • The final state of a t¯system is primarily clas- t sified by the decay modes of the two W bosons: • Various decay modes make top physics interesting and useful Name Fully Hadronic Signature jets BR 45.7% xsec at 10 TeV 191.5 pb • The top interfere with a number of new physics signatures. • Lepton + Jets e + jets 17.2% 71.9 pb µ + jets 17.2% 71.9 pb Typical search modes: Dilepton eµ + jets µµ + jets 3.18% 1.59% 13.3 pb 6.67 pb • Lepton + jets (e/mu) ee + jets 1.59% 6.67 pb • Dileptonic Tau + Jets Lepton + Tau τ + jets τ + e/µ + jets 9.49% 3.54% 39.8 pb 14.8 pb • All hadronic Tau + Tau τ + τ + jets 0.49% 2.06 pb • Tau channels total all 100% 419 pb • E.g. If mW<mH+<mt and tanβ>>1, top can decay into charged higgs, • Diboson (ME: MC@NLO, PS: Herwig + Jimmy) enhancing the τ lepton rate. The MC samples were generated with 5 TeV against 5 TeV beam energy. CTEQ 6 PDF set was used and the top mass was set to be 172.5 GeV. Alpgen MLM matching threshold was set to akira.shibata@nyu.edu Workshop of the Americas ’09 3
  5. 5. 80 90 100 110 120 130 140 150 160 MH+ [GeV] Search for Charged Higgs FIG. 10: Observed (blue) and expected (red) limit with one standard deviation band (yellow) on Br(t → H + b) of charged Higgs mass for simultaneous fit of Br(t → H + b) and σtt in the tauonic model. ¯ DØ Run II Preliminary MH+ [GeV] + H # cs H+ # " ! DØ Note 5715-CONF 180 Expected limit 95% CL Expected limit 95% CL Excluded 95% CL Excluded 95% CL 160 140 tauonic leptophobic 120 100 80 1 10 tan $ FIG. 11: Observed (blue) and expected (red) limit with one standard deviation band (yellow) on charged Hi function of tan β. Research Council and WestGrid Project (Canada), BMBF (Germany), A.P. Sloan Foundation, Civil Workshop of the Americas ’09 4 and Development Foundation, Research Corporation, Texas akira.shibata@nyu.edu Advanced Research Program, and the A
  6. 6. 80 90 100 110 120 130 140 150 160 MH+ [GeV] Search for Charged HiggsFIG. 10: Observed (blue) and expected (red) limit with one standard deviation band (yellow) on Br(t → H + b) of charged Higgs mass for simultaneous fit of Br(t → H + b) and σtt in the tauonic model. ¯ DØ Run II Preliminary MH+ [GeV] + H # cs H+ # " ! DØ Note 5715-CONF 180 Expected limit 95% CL Expected limit 95% CL Excluded 95% CL Excluded 95% CL 160 140 tauonic leptophobic 120 100 80 1 10 tan $ Good tau/jet calibration and backgroundand expected (red) limit with one standard deviation band (yellow) on charged Hi FIG. 11: Observed (blue) control is essential for this search. Not a “Day-1 physics” function of tan β. Research Council and WestGrid Project (Canada), BMBF (Germany), A.P. Sloan Foundation, Civil Workshop of the Americas ’09 4 and Development Foundation, Research Corporation, Texas akira.shibata@nyu.edu Advanced Research Program, and the A
  7. 7. onance Search New Physics into Top overlapping ν e ¯ Fraction/25GeV 0.22 ulate pp invariant → t for tt pairs the → X mass t (a) SM tt 0.2 pp → X → t t for a bump! ¯ b W + 0.18 X!tt MX=450GeV X!tt MX=650GeV pp → b ¯ → W − t W + t ¯ 0.16 b the dominant background is Standard 0.14 X!tt MX=1000GeV pp → b ¯ → W − t W + t ¯ 0.12 el tt! b t boosted 0.1 DØ Preliminary pp → g g → gt g t ¯ challenges for large masses (> 1 TeV) 0.08 0.06 ghly boosted g → gt ¯ pp → topgquarks g t X 0.04 0.02 00 200 400 600 800 1000 1200 verlapping decay products Mtt [GeV] construct “top quark jets” ¯ t boosted Topcolor Z’ excluded < 800 GeV. If new physics is leptophobic, Kaluza-Klein gluon excluded < 1TeV FIG. 1: Shape comparison of expected tt invariant mass distribut s limits depend on the theoretical model they may couple strongly to (histogram) compared to resonant production from narrow-wid for (a) 3 jet events and (b) ≥ 4 jet events. ematic errors similar to those for tt W− s-section Otherwise, dimuon is a top. ¯ clearer signature. q b VI. SYSTEMATIC ¯ q The systematic uncertainties can be classified as those a of any of the signal or background invariant mass distri overlapping 8 normalization include the theoretical uncertainty on the S luminosity (6.1%) [29] and the uncertainty of lepton identifi Workshop of the Americas ’09 5 akira.shibata@nyu.edu The systematic uncertainties affecting the shape of the inv
  8. 8. onance Search New Physics into Top overlapping ν e ¯ Fraction/25GeV 0.22 ulate pp invariant → t for tt pairs the → X mass t (a) SM tt 0.2 pp → X → t t for a bump! ¯ b W + 0.18 X!tt MX=450GeV X!tt MX=650GeV pp → b ¯ → W − t W + t ¯ 0.16 b the dominant background is Standard 0.14 X!tt MX=1000GeV pp → b ¯ → W − t W + t ¯ 0.12 el tt! b t boosted 0.1 DØ Preliminary pp → g g → gt g t ¯ challenges for large masses (> 1 TeV) 0.08 0.06 ghly boosted g → gt ¯ pp → topgquarks g t X 0.04 0.02 00 200 400 600 800 1000 1200 verlapping decay products Mtt [GeV] construct “top quark jets” ¯ t boosted Topcolor Z’ excluded < 800 GeV. If new physics is leptophobic, Kaluza-Klein gluon excluded < 1TeV FIG. 1: Shape comparison of expected tt invariant mass distribut s limits depend on the theoretical model they may couple strongly to (histogram) compared to resonant production from narrow-wid for (a) 3 jet events and (b) ≥ 4 jet events. ematic errors similar to those for tt W− s-section Otherwise, dimuon is a top. Good control of SM top and jet q ¯ b clearer signature. ¯ q resolution & jet substructure. VI. SYSTEMATIC The systematic“Day-1 physics”those a Not a uncertainties can be classified as of any of the signal or background invariant mass distri overlapping 8 normalization include the theoretical uncertainty on the S luminosity (6.1%) [29] and the uncertainty of lepton identifi Workshop of the Americas ’09 5 akira.shibata@nyu.edu The systematic uncertainties affecting the shape of the inv
  9. 9. =/,;/,",96$>;/$"#9$";?$?#(6,-6$6&@5/;&?6 ! A;?B?.,/$-/;66B69-",;4 ! C6".@',6#,45$"#9$""@./$6,54.'$.6$6;;4$.6$?;66,@'9$,4$0,'9?";4$9979 C6".@',6#,45$"#9$""@./$6,54.'$.6$6;;4$.6$?;66,@'9$,4$0,'9?";4$9979µ7µµ .40$97µSN9"6 A HUGE amount ! A#9$<.,4$>;-&6$;>$"#9$D9/($9./'($2;/3$ ;@N9-"$09>,4,",;46$.40$69'9-",;4$-&"6$2,''$@9$ A#9$<.,4$>;-&6$;>$"#9$D9/($9./'($2;/3$B of work is going @&,'0,45$@';-3$>;/$;"#9/$";?$6&@5/;&?6 into understanding ! E"&0(,45$?/;0&-",;4$0,6"/,@&",;46$F0!70?AO$0!70" 9"-T 70? the potential of ! 8;/9$?/9-,69$<9.6&/9<94"$;>$GB69-H$.00,45$;"#9/$-#.449'6$F 69-H$.00,45$;"#9/$-#.449'6$F#O$>&''($#.0/;4,-T ! E,45'9$";? first-year data. We ! I990$8J$69'9-",;46$.40$@B".55,45K$6"./"$6"&0(,45$-;4"/;'$0,6"/,@4 .40$6(6"9<.",-6 ".55,45K$6"./"$6"&0(,45$-;4"/;'$0,6"/,@ will look at the ! C4;&5#$6,54.'$9D94"6$";$699$"B-#.449'$?/;0&-",;4$2,"#$)**$?@BUO$6(6"9<.",-6$./9$39( -#.449'$?/;0&-",;4$2,"#$)**$?@ most promising tT ! A;?$<.66 cross-section ! L;<<,66,;4,45$<.66$/9-;46"/&-",;4$F;D9/'.?$2,"#$-/;66 L;<<,66,;4,45$<.66$/9-;46"/&-",;4$F;D9/'.?$2,"#$-/;66B69-",;4$B 699$<.66$?9.3T measurements in ! C6".@',6#,45$-;4"/;'$;>$6(6"9<.",-6$9M5M$;4$',5#"$.40$@ C6".@',6#,45$-;4"/;'$;>$6(6"9<.",-6$9M5M$;4$',5#"$.40$@BN9"$949/5($6-.'96 detail here. ! A;?$?/;?9/",96 ! L;<<,66,;4,45$>&''$;@N9-"$/9-;46"/&-",;4$>;/$.45&'./$<9.6&/9<94"6O$<"" .40$";?B -#./59$-.4$6"./"$2,"#$/9'.",D9'($6<.''$,4"95/."90$'&<,4;6,"( ! P40$>;/$"#9$/9-;46"/&-",;4$5/;&?$B 6&??;/",457-;<<;4$";$.''$5/;&?6 ! L;<<;4$;@N9-"$69'9-",;47?9/>;/<.4-9$6"&0,96O$/9-;46"/&-",;4$-;09O$Q=Q6$9"- !"#$%&'($)**! +,-#./0$1.23,456$7$8./",49$:;6<.4 R Workshop of the Americas ’09 6 akira.shibata@nyu.edu
  10. 10. State of the Art at Tevatron Cross-Section Measurement • Semileptonic channel • High branching ratio (~36/81) • Event over-constrained • Manageable background • Dileptonic channel • Low background • Low branching ratio (~9/81) • Event under-constrained • Fully hadronic channel • Event fully constrained • Huge QCD and comb. background • Lepton + Track • Highly inclusive • Different systematics for track performance. 8% precision all combined (summer 2008) Workshop of the Americas ’09 7 akira.shibata@nyu.edu
  11. 11. Graph !t t [pb] RULES OF THUMB 1.2 1000 CDF Results ! Running at 10 TeV takes ~twice as 1 much data as 14 TeV for equivalent Xsec relative to 14 TeV LHC 14 TeV @ 100pb-1 Expectations (CSC) 0.8 sensitivity W, Z Theoretical NLO (pp) 0.6 Top 800 Theoretical NLO (pp) ! Running at 8 TeV takes ~twice as Z' (2 TeV) Theoretical NLO+NNLL much data as 10 TeV for equivalent ee/μμ/eμ 0.4 sensitivity NLO+NNLL Scale Uncertainty 0.2 600 0 e/μ+jets Graph 12 ! Below 8 TeV things go “pear 0 2 4 6 8 10 12 14 16 ! [pb] Produced by Akira Shibata and Ulrich Husemann tt 10 shaped” quickly. CM Energy (TeV) 8 400 6 4 2 Produced by Akira Shibata and Ulrich Husemann We know a lot about top 4 200 1 1.5 2 2.5 already, from Tevatron and [hep-ph/0204244] [arXiv:0907.2527] theorists, but LHC will show 0 us a LOT more. Priced 0 2 4 14 6 8 10 12 steeply in TeV, much more s [TeV] so than the background. NB: Large uncertainty in theory due to PDF not shown. CSC assumed 5% luminosity Workshop of the Americas ’09 8 akira.shibata@nyu.edu
  12. 12. Dhiman Chakraborty The Top Quark First year detector is less than ideal Top Physics Potential Numerous uncertainties that Triggering affect measurements with the W tb coupling, |Vtb | Lepton ID + early data: Top mass, width, spin, charge Top mass constraint • Trigger efficiency W mass constraint • Non-uniform detector Initial state rad. • Lepton identification Luminosity W+ ν • Missing Et calibration and tails Production PDF section cross e + /¯ q Missing Et • Light/b jet energy scale t • QCD activity (MI, ISR/FSR) Resonant production ? Pile-up X b • Beam related issues (Pile-up, Underlying event Production Yukawa coupling ? Luminosity) kinematics B-tagging ! • PDF Spin e−/q ¯ t Bjet energy scale • Background normalization polarization Kinematic fit B fragmentation • other unknown unknowns Anomalous couplings ? ? Jet reconstruction Real performance need to be estimated from real data. Top is sensitiveRare/non-SM decays ? Light jet e scale to a variety of effect but it will also provide means for calibrationBranching fractions ? state rad. Final based on constraints in masses and decays. Workshop of the Americas ’09 9 Oct 2006 9 8 akira.shibata@nyu.edu
  13. 13. • We will look into a very recent study on single and di-lepton cross section measurements. • Much learned about the full approval process: INT approved, PUB approval in progress. • Used the “MC08” Monte Carlo samples with full Geant 4 simulation (rel 14.2.20.x) Timeline (Dilepton note) Apr 28. need for a summer note announced • Collision energy is 10 TeV. Plots and May 06. editors appointed tables are normalized to 200 pb-1. May 12. discuss selection May 22. object and event selection agreed May 26. discuss systematics May 29. systematics treatment agreed June 02. note submitted and comments received June 05. top group approval July 13. INT approval July 28. Sent to collaboration review cf: https://twiki.cern.ch/twiki/pub/Atlas/OperationModelOverviewDocument/physics_policy.pdf Workshop of the Americas ’09 10 akira.shibata@nyu.edu
  14. 14. Strategy with the First Data Do the simplest thing we can do: “cut and count” N = L σtT BR ϵtrigϵlep A + B pray for a large number but expect large uncertainty. part data driven, May not be available quickly to be estimated part MC driven well known in SM from data sensitive to theoretical uncertainty Realistically, e and mu single lepton and dilepton channels only. Taus, too difficult to calibrate. Fully hadronic too difficult to trigger. Workshop of the Americas ’09 11 akira.shibata@nyu.edu
  15. 15. Object Selection • Trigger Not fully optimized (ongoing study in Top • EF_e15_medium OR EF_mu15 Reconstruction Group) but emphasis on • Electrons simplicity and robustness, relying only on the clearest feature of the events and • egamma isEM ElectronMedium objects. • pT > 20GeV • |η| <1.37 or 1.52<|η| <2.47 • Jets • etcone20 < 6GeV • Cone4TowerJets, with pT> • Muons 20GeV, |η| < 2.5. • STACOmuons: isCombined. • Overlap removal: no selected • pT > 20GeV electrons within ∆R = 0.2 • |η| < 2.5 • No b-tagging • etcone20 < 6GeV • MEt • No overlap with jets within ∆R = 0.3 • MEt_RefFinal Workshop of the Americas ’09 12 akira.shibata@nyu.edu
  16. 16. 24 all jets 22 435jets all Event Selection - Single Lepton 1 24 all jets match 0 20 40 60 80 235 100 120 1 Missing tran 24.1.1 Jet N 0 10i 20GeV Figure 8: Missing transverse ener • Jet Multiplicity (Pt > 20 GeV) One good lepton jet multiplicity distribution (right) Jet Multiplicity (Pt > 20 GeV) Events entry (11 bins) entry (11 bins) 140 • 4 based10 background estimations afte entry (11 bins) 400 MET > 20 GeV (reduces QCD and Z) 1000 ATLAS Preliminary ATLAS Preliminary • 120 Simulation 350 Simulation 103 3 Jets with Pt > 40 GeV DRAFT July 27, 2009 – 22 : 56 (reduces W) Events Events Events Events Events 400 July 27, 2009 – 22 : 56 DRAFT 14 15 103 • 104 800 tt dilepton, ee 100 e+jets t t dilepton,tt dilepton, ee eµ 104 300 4 Jets with Pt > 20 GeV (further reduces W) 120 tt other t t other single top 102 350 • single top tt other 250 100 Z+jets 300 ReconstructTable 3: from of events which pass the various muon tt¯ signal criteria for ¯ top Number 3 highest pt jet comb 3 10 3 600 Z+jets80 W+jets single top10 102 10 250 • W+jets WW/WZ/ZZ 80 Z+jets 200 Table 2: Number of events which pass the various electron selection criteria for the selection and for the the t t signal and for the mostRequire thereatis one dijet comb−1 (left columns) and 14 TeV normalised to 14 TeV normalised to relevant backgrounds, 10 TeV normalised to 200 pb with |Mw-Mdijet| columns) and WW/WZ/ZZ ATLAS Preliminary 102 60 24 all jets Simulation W+jets 10 2 200 22 435jets all most relevant backgrounds, at 10 TeV normalised to 200 pb−1 (left 400 ATLAS Preliminary 60 1 150 A 100 pb−1 (right columns). The statistical errors due to limited Monte Carlotop) areMonte Carlo Statistics 40 also shown. <10 GeV (further(right columns).W and singledue to limited also shown. 100 pb−1 reduces The statistical errors Statistics Simulation 150 S WW/WZ/ZZ 0 20 40 60 80 100 120 are 10 40 24 all jets match 235 • 10 10 Missing 100 100 Signal efficiency ~10% analysis 200 ATLAS Preliminary 20 Simulation 50 Electron Muon analysis 20 24.1.1 Jet N 0 10i 20GeV 50 ejets μjets 1 1 120 140 160 180 200Figure 8: 0 −1140 160 −1 200 14TeV00 −1 ) 3 0 1020 Missing transverse en 10TeV (200 ) 20 pb−1 40 10TeV (200 pb (100 pb 180 100 120 ) 60 80 14TeV ) 1 20 (100 60 280 100 4 0 1 pb 0 40 60 80 100 120 1 Jet Multiplicity (Pt > 20 GeV) 0 0 40 5 6 7 8 9 1 2 3 4 5 0 2 Missing transverse energyNumber of Jets 10 4 6 8 0 Missing tran +mt cut default cut W +mt cut tdefault +MW cut 140 t0cut Jet Multiplicity (Pt jet20 GeV) 8 multiplicity distribution (righ Jet Multiplicity (Pt > 20 GeV) Missing transverse energy [GeV] 0 [GeV] Sample default Sample cut +MW default +MW +M cut +m cut +m entry (11 bins) 0 2 entry (11 bins) 2 4 6 > 10 1400 ATLAS based background estimations a entry (11 bins) 400 Jet M ttbar 2600 ± 15 ttbar ± 11 3144 ± 7 1286 581 17 1584 ± 12 1262 ± 8 561 2555 712 3274 1606 755 Jet Multiplicity (Pt >Preliminary 20 GeV) ATLAS Preliminary Missing transverse energ Figure 9: W+jets 1305 ± 33 W+jets± 20 8: Missing transverse energy distribution (left)1200Multiplicity two opposite distribution (left) afterFig. 181: Jet 350 448 Figure 1766 ± 9 108 44 628 ± 27 148 ± 13 Figure 10:after 319 transverse energy signed leptons be found in Multiplicity oppo 761 241 60 199: Jet Missing 120 (Pt > 20 GeV)Simulation and requiring two (Pt 1052 requiring 98 Simulation multiplicity distribution (right)eaft Fig. (can 210 ± 9 single top multiplicity± 9 jet 227 distribution ± 6 after ± 4cuts 23 3 183 (right) 33 all jet(except the Ndistribution 25 jets/Jet Ntt0dilepton, eµbased background estimations afte multiplicity jets > 1 cut) for jets ee dilepton signal stack.eps) found Multiplicity match/Jet N 20 10iGeV) (Pt 0 20GeV(can andbeMC jets ../../../eps/default/emu/all ../../../eps/default/ejets/all(right) after all cuts (except the N in > 1 cut) for µ je Fig. 199: Jet Events Events Events > Events Events single top 81 ± 6 27 ± 3 98 67 227 10 99 ../../../eps/default/ee/all 10i 20GeV stack.eps) 400 148 ± 4 Z→ ll +jets background estimations2after all cuts. The 8 84 120 normalized to 200pb tsingle topThe samples 350 normalized to 200p based samples are 23 100 3 −1 . 300 13 ± 1 based background estimations after all tcuts. are 104 tt dilepton, ee 1000 mu+jets 104 tt dilepton, ee Z→ ll +jets 43 ± 2 11 ±± 4 144 1 115 ± 49 35 tt other other ¯ single top tt other hadronic t t 10 t ¯3 16 ± 3 hadronic±t2 2 ±± 2 11 1 11 ± 1 5 4 2±1 0.0 35 100 17 800 7 Z+jets 300 250 The scale factors are defined as ! 3 ¯ 10 Z+jets 80 W+jets single top10 ¯ Events W+jets 1 µµ 3 64 Expected number of selected events for the ee channel selection for 20 Table2 1: 200 Events W bb 21 ± 1 W bb 7 ± 1 4 2 ±± 2 32 0 44 ± 1 10 15 ± 3 10 19 4 WW/WZ/ZZ 250 10 tt dilepton, WW/WZ/ZZ only 26 80 180 measured in data from200 Z+jets tt dilepton, µµ 1 shown for the9last 60 columnsATLAS Preliminary but2 they are fully taken into ac Z events, an W cc ¯ W cc¯ 19 tt 6 600 two 3 for readability, 10 200 7 ± 1 ATLAS2Preliminary the S/B calculation. The column labeledt ”true” represents the effect of geome t other convolution of kinematic, a 2 other Simulation W+jets 10 160 60 WW 11 ± 2 WW 6 ± 1 3 2 ±± 2 14 1 7 4 ± 1 and 7 140 single top 0.4 3 0.7 150 applyi 10 Simulation Z+jets 400 WW/WZ/ZZ Dilepton branching ratios inclu 150 WZ 3 ± 1 WZ 1 ± 1 ±0 05 ± 1 4 ± 1 0.2W+jets The 107 120labeled ”fake”0.8 2 1 ± 0.2 0.4 column 40 3 40 shows the number oftop 10 which failed the truth-ma single events 100 ATLAS Preliminarydecay. From MC@NLO top pair 10 100 Z+jets ZZ 0.4 ± 0.1 ZZ0.2 ± 0.1 2 0.1 ±± 0.1 0.5 0.1 0.2 ± 0.1 0.1WW/WZ/ZZ 0.1 0.5 0.2 0.0 ± 0.7 100 0.3 200 0.1 10 ATLAS Preliminary 20 lepton sel. inv. mass cut ET 1 0.05)% and BR(t t → eµ ) 20 Simulation W+jets (1.64 miss cut jet cut trigger ± 50 ¯ Signal 2600 Signal 1286 581 3144 2555 1262712 561 1 1584 Simulation 3274 80 1606 755 50 322 7 A(ee) = (16.5 ± 220 A(µ µ ) = ( 0.4)%, 214±6 120 1 0 20 40 60 80 100 120 140 160 180 200 ¯ dilepton 0 t t 600 400 1 60 280 351 4 4 140 160 180 200 9261 20 0 0 3100 120 5 6 6 WW/WZ/ZZ 0 10 00 40 1 60 2 80 3100 4 8 1020 Background 1715 Background598 154 1144 799transverse energy [GeV] 374201 96 2 143 8 0 15 Jet Multiplicity Preliminary10 on MC 9 13 (Pt > Based10 simulation for si 10 2199 1497 40 495 0 Missing Missing ¯ t t other3.2 Missing transverse energyNumber of Jets 0 ATLAS 6 [GeV] 20 GeV) 8±1 2 0 S/B 1.5 S/B 2.1 3.8 1.4 2.2 2.0 3.4 3.5 5.82.2 20 5.3 2 4 8 for an integrated luminosity of 200 single top 27 Jet Multiplicity (Ptmiss2018 akira.shibata@nyu.edu 9 25 9±2 Je Simulation Workshop of the Americas ’09 13 > GeV) 8 T 9 and jet multiplicity distributi 1 0 20 40 60 80 100 120 140 160 180 200 0 0 1 2 3 4 5 6 7 EFigure10 Missing transverse en 9: +2
  17. 17. ment, in percent, for electrons and muons. The entries in bold indicate the errors which are finally quoted and constitute the total estimates. The final summed totals do not include the luminosity error which is quoted separately. Source Cut and Count method e-analysis µ -analysis • Lepton efficiency to be estimated using Fit method tag and probe e-analysis µ -analysis • default +MW cut default +MW cut +MW cut +MW cut (%) (%) (%) (%) (%) Applicable after correction in η, pT (%) Stat. ± 2.5 ± 3.4 ±2.3 ±3.1 ± 14.1 and isolation. ± 15.2 • Lepton ID eff. ±1.0 ±1.0 ±1.0 ±1.0 ± 1.0 ± 1.0 Lepton trig. eff. ±1.0 ±1.0 ±1.0 ±1.0 ± 1.0 W+Jets is the dominant background ± 1.0 50% W+jets 20% W+jets JES (10%,-10%) ±25.1 ±10.0 ±17.4 ±7.0 ±28.1 ±11.2 ±19.8 ±7.9 +24.8-23.4 +15.9-19.1 +20.5-22.3 +11.9-17.9 ± 3.3 ± 1.5 -14.4 • Studied data-driven estimation based ± 5.6 ± 2.6 on Z/W ratio. Estimates 20% unc. -15.4 JES (5%,-5%) PDFs ISR/FSR +12.3-11.9 +8.6-9.3 ±1.6 +9.1-9.1 ± 1.9 +7.6-8.2 +10.4-10.9 ±1.2 +8.2-8.2 +6.1-8.4 ± 1.4 +5.2-8.3 • -3.7 ± 1.9 -12.9 -3.9 The analysis rather sensitive to JES ± 1.4 variation. -12.9 Signal MC Back. Uncertainty Fitting Model ±3.3 ±0.6 - ±4.4 ±0.4 - ±0.3 ±0.5 - ±2.8 ±0.4 - ± 4.5 - ± 3.3 • ± 1.4 Constant scaling of jet energy applied - (MEt varied correspondingly). ± 4.7 • 10% Lumi. ±11.6 ±11.2 ±11.4 ±11.1 ±10 ±10 20% Lumi. ±23.2 ±22.3 ±22.8 ±22.2 ±20 ISR/FSR effects evaluated using Pythia ± 20 Tot. without Lumi. +18.8-18.5 +14.4-15.2 +17.5-17.7 +11.9-14.7 • Variation of ΛQCD and cutoff leads to +6.4 -14.9 +6.0 - 14.7 large variation. Bold is used in final combination 538 6.7 Cross-section Evaluation with the Baseline analysis With the first 200 pb−1 ¯ of data, we demonstrate that we can observe a t t • By far the dominant effect is the signal anduncertainty on Luminosity. determine its 540 production cross-section. In the default scenario with 5% JES uncertainty and 20% uncertainty on the ¯ W+jets background this simple method yields the following uncertainty on the t t cross-section using the 542 default lepton analysis plus the MW cut in the Cut and Count method: Workshop of the Americas ’09 14 akira.shibata@nyu.edu

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