General EWK Meeting 20-01-09 Christopher Rogan California Institute of Technology - PowerPoint PPT Presentation

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General EWK Meeting 20-01-09 Christopher Rogan California Institute of Technology
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General EWK Meeting 20-01-09 Christopher Rogan California Institute of Technology

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  1. V+jets m/e studies with 21X: Status and plans General EWK Meeting 20-01-09 Christopher Rogan California Institute of Technology for Marcella Bona, Emanuele Di Marco, Ran Feldesh, Joseph D. Lykken, Paolo Meridiani,C.R., Chiara Rovelli, Maurizio Pierini, Ilaria Segoni, Maria Spiropulu, Thiago Tomei, Lukas Vanelderen,Marco Zanetti

  2. goal of the analyses: • candle with the Z mass: validate e and m reconstruction • application examples: • MC tuning with the dN/dnjets and dN/dpT(Z)‏ • check and correction of MET • ratios good for start-up: systematics cancel • references for 16X analyses: • CMS notes • Z+jets & W+jets Alpgen Validation: CMS AN-2008/091 • Z(ee)+jets Candle Analysis: CMS AN-2008/092 • Z(mm)+jets Candle Analysis: CMS AN-2008/095 • W(en)/Z(ee)+jets Ratio Analysis: CMS AN-2008/096 • W(mn)/Z(mm)+jets Ratio Analysis: CMS AN-2008/105 • previous EWK talks on 16X analysis: • summary by M.Pierini Nov 11th 2008 • note release: E. Di Marco, C. Rogan, and I. Segoni: Oct 17th 2008 • V+jets talks: • e and m analyses: I. Segoni and M.Zanetti: Nov 14th 2008 • m selection: M. Bona: Nov 28th 2008

  3. V+j so far Christopher Rogan - EWK Meeting 20-01-09

  4. samples: 2.1.X and Fall09 • signals, other Z/W decays andtt events: MADGRAPH • QCD: “InclusiveMu15” sample (muon enriched QCD)‏ • general strategy for the analyses • single non isolated muon trigger • muon selection: optimization in the next slides • Z mass window [60, 120] GeV/c2 • closest-to-the-leading-muon PV selection • jet clustering (calo jets and track jets: SisCone with 0.5)‏ with E/pT and h cuts (30/15 GeV and 3/2.4, respectively)‏ • 2D maximum likelihood fit: Z mass and sin(angleMET, MHT)‏ for Z+jets; transverse mass and sin(angleTS-jet)‏ • floating the shape parameters for low jet multiplicities and fixing for the high multiplicities • sPlots for verify shapes on data

  5. muon selection in 16X • only global muons • pT > 15 GeV/c • vertex variables and isolation variables simultaneous optimization: • vertex variables: Dxy/s(Dxy) and Dz(m-PV)‏ • isolation variables: tracking isolation i piT/pmT ECAL isolation R<0.35 ETECAL HCAL isolation R<0.5 ETHCAL • extensive study to select the variables and to establish the optimization procedure: done in 16X and now repeated in 21X production, the PV is displaced in x so we can calculate the distance wrt the PV but the error is calculated wrt (0,0,0)‏ so we started looking at: Dxy better for the electrons that have typically poorer tracking resolution about the same discrimination for muons (wrt the significance)‏ Hcal isolation: H0 excluded and zero suppression introduced

  6. Cut variables i piT/pmT R<0.35 ETECAL R<0.5 ETHCAL Dz(m-PV)‏ Dxy Christopher Rogan - EWK Meeting 20-01-09

  7. Optimization on the W selection • Optimize the Punzi Significance: • Consider all backgrounds and scan over all cut values simultaneously, with rates normalized to 100 pb-1 • Consider only events in ML fit ‘signal region’ Christopher Rogan - VecBos + jets 15-01-09

  8. R<0.35 ETECAL <2.25 GeV R<0.5 ETHCAL <2.8 GeV Optimization scans requiring: i piT/pmT <0.15 Christopher Rogan - VecBos + jets 15-01-09

  9. Optimization scans requiring: Dz(m-PV)‏ Dxy(PV)‏ <0.11 cm <0.005 cm Christopher Rogan - VecBos + jets 15-01-09

  10. Optimized cut values Values used Values used 0.15 0.2 0.2 (0.11)‏ 0.11 0.11 0.11 2.25 2.75 2.5 (1.6)‏ 2.0 2.0 2.0 2.8 2.8 4.1 4.0 (6.0)‏ 3.1 4.5 4.5 0.11 0.1 0.11 (0.08)‏ 0.1 0.11 0.11 0.005 0.005 0.005 (n.a.)‏ 0.0045 0.0045 0.0045 Calo jets Track jets Christopher Rogan - VecBos + jets 15-01-09

  11. Optimized cut values Calo jets Track jets Christopher Rogan - EWK Meeting 20-01-09

  12. Changing muon pt cut W selection Christopher Rogan - EWK Meeting 20-01-09

  13. Changing muon pt cut Z selection Christopher Rogan - EWK Meeting 20-01-09

  14. Analysis strategy Common requirements: Single non isolated HLT trigger (HLT_Ele15_LW_L1R) pixel-match GSF electron reconstruction electron identification* electron isolation* electron - PV compatibility calo-jet clustering (SisCone, ΔR=0.5) electron(s) from W(Z) cleaning from calo-jets jet counting * for Z, asymmetric id+iso W-specific requirements: exactly 1 electron (against Z+j) Z mass veto (decouple W+j dataset from Z+j) MET > 20 GeV (against QCD) mT(W) > 30 GeV (against QCD) Z-specific requirements: ≥2 electrons (against W+j) Z mass range (decouple Z+j dataset from W+j) yields and ratio determination: Maximum Likelihood fit efficiency correction of yields, if needed Christopher Rogan - EWK Meeting 20-01-09

  15. why re-iteration with 2.1.X ? • electron reconstruction details changed w.r.t. 1.6.X. (i.e. CSA07) • tracker material changed • some electron identification related to tracker - ECAL match can be changed • among others, H/E definition changed • pre-shower is excluded • HO is excluded and zero-suppression in HCAL has been introduced • H/E is affected • HCAL isolation is affected • PV is displaced in x w.r.t. (0,0,0) Disclaimer! In this iteration, possibly no new variables w.r.t. the ones used in CSA07 analysis are used. Various new quantities have been developed and released, will be tested in W+j/Z+j @ next round Christopher Rogan - EWK Meeting 20-01-09

  16. Electron identification tracker-ECAL match ECAL-HCAL match ECAL cluster shapes • We use the set of variables from egamma POG, with selection depending on electron classification (based on fbrem) • we compare 2.1.X - 1.6.X and re-optimize selection for golden / showering both barrel and endcap • this defines the W electron and the first Z electron (i.e. tight) • loose egamma identification on the other (asymmetric ID) Christopher Rogan - EWK Meeting 20-01-09

  17. Efficiency of ele - id • Cuts optimized simultaneously to maximize W signal significance against QCD • QCD e.m. enriched + b,c→electrons used • the optimization is driven by W+j. For Z+j, the highest pT electron is identified with the same criteria to allow efficiency cancelation in Wj/Zj • the ID of the second is based on the same variables, but looser The optimized cuts Single electron efficiency on W+≥0j selection ε(CSA07) ε(Summer08)- 93.7 +/- 0.1 95.7 +/- 0.1-*- s9s25: 95.7 +/- 0.1 95.9 +/- 0.1-*- deta: 97.6 +/- 0.1 91.2 +/- 0.1-*- dphiIn: 98.4 +/- 0.1 98.6 +/- 0.1-*- sigmaEtaEta: 93.5 +/- 0.1 96.5 +/- 0.1-*- eOverPout: 93.7 +/- 0.1 99.2 +/- 0.1 -*- total eID: 75.5 +/- 0.2 79.0 +/- 0.2 egamma loose Christopher Rogan - EWK Meeting 20-01-09

  18. S and B yields (W+j) • yields, normalized in 100 pb-1, up to electron definition. large stat error Christopher Rogan - EWK Meeting 20-01-09

  19. S and B yields (Z+j) • yields, normalized in 100 pb-1, up to electron definition Christopher Rogan - EWK Meeting 20-01-09

  20. m(e+e-) lineshapes ≥1 jet ≥2 jet ≥3 jet • Cruijff = Gaussian + exp tails for signal, parabola for inclusive bkg Z+jets (MADGRAPH) consistent parameters for signal lineshape as a function of jet multiplicity tt+jets (MADGRAPH) Christopher Rogan - EWK Meeting 20-01-09

  21. mT(W) lineshapes W+jets tt+jets Z+jets QCD • Cafu = Crystal ball + Gaussian with same mean ≥1 jet ≥2 jet decreasing importance Christopher Rogan - EWK Meeting 20-01-09

  22. slope correction Yields uncorrected Yields efficiency-corrected W+j e-Slope=7.5±1.2 e-Slope=6.9±1.1 Preliminary Z+j e-Slope=6.8±0.5 e-Slope=6.8±0.5 W/Z = 1.09±0.20 W/Z = 1.01±0.19 ⇒ eff changes the slope, but effect on double ratio is within uncertainty Christopher Rogan - EWK Meeting 20-01-09

  23. slope correction Yields uncorrected Yields efficiency-corrected W+j e-Slope=7.32±0.09 e-Slope=6.82±0.08 Preliminary Z+j e-Slope=8.0±0.4 e-Slope=7.4±0.3 W/Z = 0.91±0.05 W/Z = 0.93±0.04 ⇒ eff changes the slope, but effect on double ratio is within uncertainty Christopher Rogan - EWK Meeting 20-01-09

  24. for the candle analysis: • we start from the optimization values obtained for the ratio in the W selection we can afford to loosen the cut to increase efficiency • muon pT > 10 GeV/c • vertex variables: Dxy <0.02 cm& Dz(m-PV) <0.15 cm • isolation: i piT/pmT<0.30 (on the second leg)‏ Preliminary Christopher Rogan - VecBos + jets 15-01-09

  25. Background ≥1jet ≥1jet Preliminary Christopher Rogan - EWK Meeting 20-01-09

  26. Signal ≥2jet ≥1jet ≥4jet ≥3jet Christopher Rogan - VecBos + jets 15-01-09

  27. Background ≥1jet ≥2jet ≥3jet ≥4jet Christopher Rogan - VecBos + jets 15-01-09

  28. Signal ≥1jet ≥2jet ≥3jet ≥4jet Christopher Rogan - VecBos + jets 15-01-09

  29. Background ≥1jet ≥2jet ≥3jet ≥4jet Christopher Rogan - VecBos + jets 15-01-09

  30. for the electron candle analysis: we can afford to loosen the cut to increase efficiency • electron pT > 10 GeV/c • loose electron ID on both legs • Best Z candidate choice (highest pt electrons) • vertex variables: Dxy <0.04 cm& Dz(m-PV) <0.12 cm • isolation: i piT/pmT<0.15 (on both legs)‏ Preliminary Christopher Rogan - VecBos + jets 15-01-09

  31. Signal ≥1jet ≥1jet ≥2jet ≥2jet Christopher Rogan - EWK Meeting 20-01-09

  32. Background ≥1jet ≥1jet ≥2jet ≥2jet Christopher Rogan - EWK Meeting 20-01-09

  33. EXTRA SLIDES Christopher Rogan - EWK Meeting 20-01-09

  34. Madgraph/Alpgen Production changes 34 For tt+j • parton pt 20, matched at 30 MADGRAPH – KT MLM matching • x-section 317pb @ 10 TeV, x-section 750 pb @ 14 TeV • Parton pt 70, matched at 20 GeV, ALPGEN –MLM (old, IC) Matching • x-sec 450 pb @14 TeV – if 20 GeV parton pt x-sec 754 pb@14 TeV, • x-section 270 pb@ 10 TeV [15% compared to MAD, MAD>ALPGEN but different scales, PDFs see below] • Scale (m_top)^2 at MADGRAPH • Scale (M_T)^2=sum(m_top^2+P_T^2) ALPGEN • Lower Q^2 pushes the cross section up (MAD>ALPG) (10%) • PDF CTEQ6L NLO and corresponding a_s change in MADGRPAH • PDF CTEQ5L LO ALPGEN • NLO PDF pushes x-section up (MAD>ALPG) (10%) Christopher Rogan - EWK Meeting 20-01-09

  35. Comparison of isolation variables: CSA07 - FALL08 Christopher Rogan - VecBos + jets 15-01-09

  36. Comparison of vertex variables: CSA07 - FALL08 significance Christopher Rogan - VecBos + jets 15-01-09

  37. tracking isolation: tracks within DR < 0.5 • at least 5 associated hits • |Dz(track-PV)| < 0.1 cm • |Dxy/s(Dxy)| < 5 • 500 MeV/c < pT < 500 GeV/c • isolation variables: tracking isolation normalized: i piT/pmT ECAL isolation: R<0.35 ETECAL HCAL isolation: R<0.5 ETHCAL ECAL isolation: EM calotowers in the 0.35 cone around the m m energy is not subtracted HCAL isolation: hadronic calotowers in the 0.5 cone Christopher Rogan - VecBos + jets 15-01-09

  38. W selection efficiencies Preliminary Christopher Rogan - VecBos + jets 15-01-09

  39. Z selection efficiencies Preliminary Christopher Rogan - VecBos + jets 15-01-09

  40. Eseed/Pout • Major point: track pout estimation depends by the tracker material knowledge barrel endcap Christopher Rogan - EWK Meeting 20-01-09

  41. Δηvtx • GSF-track - ECAL supercluster match • larger tails for non-showering • non-showering endcap bumps for η>0, η<0: tilt changed in the geometry? barrel endcap Christopher Rogan - EWK Meeting 20-01-09

  42. ΔΦvtx • GSF-track - ECAL supercluster match barrel endcap Christopher Rogan - EWK Meeting 20-01-09

  43. H/E • CSA07: H/E = sum(H rechits) / supercluster energy in cone ΔR=0.1 • no HCAL zero-suppression • Summer08: H/E = max (H rechit / basic cluster ), the H rechit is the one above the ECAL basic cluster • HCAL zero - suppression barrel endcap Christopher Rogan - EWK Meeting 20-01-09

  44. s9/s25 • Cluster shape variable barrel endcap Christopher Rogan - EWK Meeting 20-01-09

  45. σηη • Cluster shape variable (cluster width) • changed thresholds? barrel endcap Christopher Rogan - EWK Meeting 20-01-09

  46. i piT/pmT R<0.35 ETECAL R<0.5 ETHCAL Dz(m-PV)‏ Dxy(PV)‏ Optimization scan requiring: Christopher Rogan - VecBos + jets 15-01-09

  47. i piT/pmT R<0.35 ETECAL R<0.5 ETHCAL Dz(m-PV)‏ Dxy(PV)‏ Optimization scan requiring: Christopher Rogan - VecBos + jets 15-01-09

  48. i piT/pmT R<0.35 ETECAL R<0.5 ETHCAL Dz(m-PV)‏ Dxy(PV)‏ Optimization scan requiring: Christopher Rogan - VecBos + jets 15-01-09

  49. Optimization • Some comments: • Currently we are not including a sphericity cut or MET cut in the optimization (we will include this once I finish the W MET calibration using the Z candle) • As a result, we are cutting more tightly on these five variables relative to what we will do when including MET or sphericity - I anticipate that the signal efficiency will go up with • Ultimately, we will also do the optimization in the signal region of the ‘angular variable’ which we use in the fit - we can’t do this until we have the W MET calibration. • Hence these are probably not the ‘final’ values, but they demonstrate the procedure/philosophy of the optimization Christopher Rogan - EWK Meeting 20-01-09

  50. what looks different • Most of the electron ID variables looks very similar to CSA07. (see backup) • larger differences in: H/E, σηη • H/E: definition changed, was H/E in a cone ΔR=0.1, now is Hover-ECALseed/Eseed • σηη: noise threshold for covariance matrix calculation changed (w0=4.2 → 4.7): expected larger width H/E barrel σηη barrel Christopher Rogan - EWK Meeting 20-01-09