RD. Schaffer, L. Iconomidou Fayard, D. Fournier Impact of new trackselection, new track extrapolation on the H4e analysis. Fany Dudziak RD. Schaffer, L. Iconomidou Fayard, D. Fournier Higgs WG meeting March 27, 2009

Reminder H->4l (M=130GeV) suffers from low efficiency coming from the Z*->lowPt electrons. Essentially radiating electrons The track/cluster matching is sensitive to brems which produce a lower reconstructed track momentum  E.g from the simple formula: dphi =8.6 mrad *(50GeV/ptelec)*(rclus/rcalo) ..one sees that a 25GeV Pt electron with E/p=2 will be shifted by 20mrad and will be rejected by the standard Δφ cut (20mrad).  Important losses of efficiency for low Pt Electrons due to cut on Δφ(tr-cal) cut  Rescaling the momentum and extrapolating from the perigee improves the track/cluster matching conserving these electrons

Overview We compare efficiencies/rejections for electrons in releases (dataset used for studies: H4l130): « Standard reco »  : i.e. rel 14.2.X Release 15.0 : changes in track match and priority for electrons vis- a-vis conversions. Here we will use : “Simulated” Rel 15.0 = “Simulated” Rel 15.0 starting from Rel14 and WITHOUT E/P cut Release 15.0 + new track extrap : available as option in rel 15.1 We show impact on the H->4e analysis for a set of MH (120,130,150 and 200 GeV) Reminder : For CSC note comparison: - Conversions are kept in Electron Container - Since CSC, isEM has changed: E.g. Medium now has Δη<0.005 and calo iso cut in.

Datasets, release Mc08 samples : H4l mc08.105300.PythiaH130zz4l.recon.AOD.e352_s462_r604_tid032239/40 mc08.106300.PythiaH120zz4l.recon.AOD.e352_s462_r604_tid038862/63/039066 mc08.106301.PythiaH150zz4l.recon.AOD.e352_s462_r604_tid038858 mc08.106301.PythiaH150zz4l.recon.AOD.e352_s462_r604_tid038859 mc08.106305.PythiaH200zz4l.recon.AOD.e352_s462_r604_tid038861 mc08.106305.PythiaH200zz4l.recon.AOD.e352_s462_r604_tid038860 DiJets minbias : mc08.105805.filtered_minbias6.recon.AOD.e347_s462_r604_tid032288- 89-90-91-92- 039063 Zz4l mc08.109292.Pythiazz4l_3MultiLeptonFilterElecMu.recon.AOD.e379_s462_r617 Analysis with 14.5.2.2 EMPhotonToElectron tool used to make the new electrons with a modified EMTrackMatch tool (in rel 15.1) egammaMCTruthClassifier used to classify the electrons in jet sample

TrackMatch definition VS Releases Rel 14.2.2x: Extrapolate the track to calo from the last measurement point Has losses due to : E/P cut at <10 Choose the best track in φ => sometime took TRT track instead of Si track Priority given to conversions => electrons end up in photon container Rel 15 reco: Recuperate above losses: Select preferentially tracks with hits in Pixel and SCT E/P cut removed (finally not, but removed here for studies) Conversions ignored for electrons New trackmatch As in Rel 15 with removed E/p. Rescale track momentum and extrapolate from perigee Recuperates effects of bremsstrahlungs

From Rel14=>Simulated Rel15+NewExtrapolation: How to make a new (transient) container of electrons EMPhoton- -toElectron + EMTrack- Match photons != 2 Electrons author&0x1 New electrons 2.8% of e rejected by trackMatch 19.1% of γ remain γ rejected NB :The different TrackMatch algorithm are simulated via our EMPhotonToElectronTool

Results on electrons

The New deltaPhi trackMatch Signal e Fake e deltaPhi(tr-cal) deltaPhi(tr-cal) Rel14 Δφ : asymmetric + large tails Rel15+newΔφ : more symmetric + narrower Rel14 Δφ : peak centered at 0 Rel15+ New Δφ : peak off-centered and wider because of energy rescaling

Rejection vs efficiency CSCnote for et>20GeV CSCMedium : MediumRel14 - CaloIsolation-DeltaEta

Sim15.0+new extrapolation Efficiency % Electron candidates loose medium medium + Δφ 14.0 88.3 ± 0.2 86.0 ± 0.2 73.5 ± 0.2 69.2 ± 0.2 Sim15.0 96.0 ± 0.1 93.6 ±0.1 80.1 ±0.2 74.2 ±0.2 Sim15.0+new extrapolation 98.7 ± 0.1 96.2 ±0.1 81.8 ±0.2 80.3 ±0.2 +11.1% +8.3% Simulated 15.0 +new extrapolation: Improvement by 8.3% (absolute) vs Rel14 and by 1.7% (absolute) vs Rel 15 for mediumId efficiency With Medium+Δφ cut: small loss vs Medium (-1.5% in 15.0+New instead of -5.9% in 15.0) . Allows to improve fake rejection

Efficiency -- Rel 14.0 eff =73.5% efficiency -- 15.0 electrons eff =80.1% -- 15.0 +new extrapolation eff =81.8% efficiency Pt(GeV) efficiency Gain more events at low Pt and at large eta η

SimRel 15.0+new extrapolation Rejection Min bias sample : Pt>8GeV Electron fake = electron with electrontype==4 in egammaMCTruthClassifier Rejection = nb_event *0.31 /(nb_cut * 0.057) loose medium medium + Δφ Rel 14.0 640 ± 9 3638 ± 119 4705 ± 177 SimRel 15.0 ± 11 4018 ± 129 4551 ± 156 SimRel 15.0+new extrapolation 611 ± 8 3817 ± 119 5052 ± 181

Results on H4e analysis

H->ZZ*->4e 130 GeV +35.3% +5.7% Rel 14 (%) Rel 15 (%) Rel 15 +new Extrapolation (%) 4e loose, |η|<2.5 61.5 ±0.7 79.4 ±0.5 87.2 ±0.5 2e w/ Pt>20 GeV 4 w/ Pt>7GeV 47.1 ±0.7 62.7 ±0.7 69.1 ±0.6 mZ, mZ* (*) 18.9 ±0.5 25.0 ±0.6 26.8 ±0.6 |m4e-130|<10 GeV |m4e-130|<4.4 GeV (2σ) 18.1 ± 0.5 15.0 ±0.5 23.9 ± 0.5 19.2 ±0.5 25.6 ± 0.5 20.3 ± 0.5 +35.3% +5.7% To be compared with 12.5% of efficiency in csc for H4e but with 2 more cuts (impact parameters, track cone ~>2%) (*) opposite charges, electron medium, |me1e2-mZ|<15 GeV, mZ*>20 GeV

H->ZZ*->4e different masses Efficiencies for cut on mH ± 2σ for different possible masses of the Higgs Rel 14 (%) Rel 15 (%) Rel 15 +new Extrapolation (%) H 120 GeV 10.5 ± 0.4 14 ± 0.5 14.7 ± 0.5 H 130 GeV 15.0 ± 0.5 19.2 ± 0.5 20.3 ±0.5 H 150 GeV 18.3 ± 0.5 23.5 ± 0.6 24.3 ± 0.6 H 200 GeV 27.8 ± 0.7 36.1 ± 0.7 37.8 ± 0.5

Summary about Higgs efficiencies ---14 ---15 (without E/P cut) ---15+new extrapolation Gain in efficiency: 14-15 15-15+ 14-15+ 120 GeV 28.4% 5% 34.9% 130 GeV 22.7% 5.4% 29.3% 150 GeV 27.0% 3.4% 31.4% 200 GeV 28.5% 4.7% 34.5%

Background to the H4e signal ZZ4e : for 130 GeV Rel 14 (%) Rel 15 (%) simulée Rel 15 +new Extrapolation (%) 4e loose, |η|<2.5 57.4 ± 0.4 78 ± 0.4 85.3 ± 0.3 2e w/ Pt>20 GeV 4 w/ Pt>7GeV 50.0 ± 0.4 69.3 ± 0.4 76.1 ± 0.4 mZ, mZ* (*) 28.1 ± 0.4 38.5 ± 0.4 40.8 ± 0.4 |m4e-200|<7.8 GeV 0.28 ± 0.05 0.63 ±0.07 0.7 ± 0.1 X2 the zz4l background as we increase efficiency for electrons

Summary about Higgs efficiencies Gain in efficiency: 14-15 15-15+ 14-15+ 120 GeV 33.3% 5% 40% 130 GeV 28% 5.7% 29.3% 150 GeV 28.4% 3.4% 32.8% 200 GeV 29.9% 4.7% 36% ---14 ---15 ---15+new extrapolation Increase with Pt Decrease with Pt

Summary Rel 15.0 electron reco improves electron efficiency relative to rel 14 (6.6% in absolute at medium level) Further improvement is obtained with a rescaled momentum extrapolation from perigee for efficiency and rejection: For efficiency : 8.3% in absolute for medium For rejection : 10.4% of gain for 14->15 and 5% for 14->15+ new extrapolation Application to the H4l analysis shows encouraging results at 130 GeV efficiency increased by 22.7% for 14->15 and 29.3% for 14->15+ new extrapolation

Back-up slides

H->ZZ*->4e 120 GeV +34.9% +5% Rel 14 (%) Rel 15 (%) Rel 15 +new Extrapolation (%) 4e loose, |η|<2.5 60.1 ±0.7 77.5 ±0.5 84.9 ±0.5 2e w/ Pt>20 GeV 4 w/ Pt>7GeV 41.8 ±0.7 55.2 ±0.7 60.5 ±0.7 mZ, mZ* (*) 13.4 ±0.5 18.2 ±0.5 19.3 ±0.6 |m4e-120|<4.4 GeV 10.9 ±0.5 14.0 ±0.5 14.7 ±0.6 +34.9% +5% (*) opposite charges, electron medium, |me1e2-mZ|<15 GeV, mZ*>15 GeV

H->ZZ*->4e 150 GeV +31.4% +3.4% Rel 14 (%) Rel 15 (%) Rel 15 +new Extrapolation (%) 4e loose, |η|<2.5 64.1 ±0.7 83.5 ±0.5 90.0 ±0.4 2e w/ Pt>20 GeV 4 w/ Pt>7GeV 56.0 ±0.7 74.6 ±0.6 81.2 ±0.5 mZ, mZ* (*) 23.6 ±0.6 31.4 ±0.6 33 ±0.6 |m4e-150|<4.6 GeV 18.5 ±0.5 23.5 ±0.5 24.3 ±0.6 +31.4% +3.4% (*) opposite charges, electron medium, |me1e2-mZ|<15 GeV, mZ*>30 GeV

H->ZZ*->4e 200 GeV +34.5% +4.7% Rel 14 (%) Rel 15 (%) Rel 15 +new Extrapolation (%) 4e loose, |η|<2.5 64.9 ±0.8 84.9 ±0.5 91.3 ±0.4 2e w/ Pt>20 GeV 4 w/ Pt>7GeV 60.9 ±0.8 82.2 ±0.7 89.1 ±0.4 mZ, mZ* (*) 34.5 ±0.5 45.2 ±0.7 47.8 ±0.7 |m4e-200|<7.8 GeV 28.1 ±0.5 36.1 ±0.7 37.8 ±0.5 +34.5% +4.7% (*) opposite charges, electron medium, |me1e2-mZ|<15 GeV, mZ*>60 GeV