Simulation of the Measurement of the Inclusive Jet Cross Sections in Z(ee/mumu)+jets Events in pp Collisions at 14TeV with the ATLAS experiment.

E.Segura thesis (June 2009)

Here is the final version of my PhD thesis, in ps format (here) and pdf fomat (here).

Z+ jets Plots for the CSC note (2008):

Here are the plots from Z+jets Analysis, including Z->ee and Z->μμ (CSC note: "Measurement of Z+jets Cross-Section at ATLAS") for future conferences (plots "blessed" at Atlas SM meeting on 2nd July 2008 (link))

Data Samples used: Zee + jets

Process Generator Dataset
signal Z -> ee Alpgen/Herwig 8130 - 8135
QCD dijets JF17 Pythia 5802
Top Pythia 5568
W -> e ν Pythia 5104
Z-> ττ Pythia 5146

Data Samples used: Zμμ +jets

Process Generator Dataset
signal Z -> μμ Alpgen/Herwig 8142-8147
QCD dijets (bb(μμ)) Pythia 17506
Top Pythia 5568
W -> μ ν Pythia 5105
Z-> ττ Pythia 5904

Event Selection: Zee +jets

  • Two electrons with PT > 25 GeV in |η| < 2.4, excluding 1.37 < |η| <1.52 (barrel-to-endcap calorimeter crack region)
  • medium electron-ID signature
  • deltaR (electron, electron) > 0.2
  • Jet cuts (using Calorimeter Tower Cone 0.4 jet algorithm):
    • PT > 40 GeV
    • |η| < 3.0
    • Remove jets which are within ΔR = 0.4 of the electron
    • Invariant mass cut: 81-101GeV

Event Selection: Zμμ +jets

  • Two muons with PT > 15 GeV in |η| < 2.4 & |η| > 0.1 (holes for service passages) & outside 1.2 < |η| <1.3 (some MDT-chambers missing in the initial-layout of the Muons Spectrometer)
  • Isolation: Energy in the ΔR = 0.2 cone around muon < 15 GeV
  • Jet cuts (using Topological Cluster Cone 0.4 jet algorithm):
    • PT > 40 GeV
    • |η| < 3.0
    • Remove jets which are within ΔR = 0.4 of the muon
    • Invariant mass cut: 81-101GeV

Lepton reconstruction in the presence of jets

  • deltaR (electron, electron) (.eps) (.png):
    Eldr_All.png

Signal and Background: Zee +jets

Distributions of the di-electron mass, inclusive jet multiplicity, PT of the leading and second leading jet in the electron channel for L = 1fb-1.

  • Z(e,e) invariant mass for signal + background (.eps) (.png):
    Ana_Minv1.png

  • Inclusive jet multiplicity (signal+background) (.eps) (.png):
    Ana_Njet.png

  • PT leading jet distribution for signal+backgrounds (.eps) (.png):
    Ana_Jpt0.png

  • PT 2nd leading jet for signal+backgrounds (.eps) (.png):
    Ana_Jpt1.png

Signal and Background: Zμμ +jets

Distributions of the di-muon mass, inclusive jet multiplicity, PT of the leading jet and second leading jet for signal and backgrounds in the muon channel. In order to provide higher statistics for the background determination, background events in an invariant mass of 51 - 131 GeV, are scaled down for an invariant mass window of 81 - 101 GeV.

  • Z(mu,mu) invariant mass for signal + background (.eps) (.png):
    SM_invmass_new81101.png

  • Inclusive jet multiplicity (signal+background) (.eps) (.png):
    SM_njets_new81101.png

  • PT leading jet distribution for signal+backgrounds (.eps) (.png):
    SMptleadjetbgdpythiaFactor.png

  • PT 2nd leading jet distribution for signal+backgrounds (.eps) (.png):
    SMpt2leadjetbgdpythiaFactor.png

Correction from parton to hadron level

MCFM predictions have to be corrected with respect to non-perturbative effects of fragmentation and underlying event (UE), from parton level to hadron level. Cone 0.4 jet algorithm has been used.

  • Fragmentation correction (.eps)(.png):
    C4_corr_frag_jpt.png

  • Fragmentation + Underlying Event correction (.eps)(.png):
    C4_corr_all_jpt.png

Unfolding detector effects

Comparison of the distribution of the PT of the leading jet and the 2nd leading jet for the generated Monte Carlo and for the reconstructed quantities without any correction, after the corrections for electron triggering and reconstruction and after applying in addition the jet-related corrections.

Comparison of MCFM predictions and Alpgen/Pythia (at hadron level)

Comparison of the inclusive jet cross-section and the PT of the leading jet and of the 2nd leading jet for the Zμμ +jets channel for PYTHIA and ALPGEN Monte Carlo with NLO (LO) MCFM predictions.

  • Inclusive jet cross-section (.eps)(.png):
    10njetsmcfmtruth.png

JES uncertainty

Analysis simulation results

Comparion for the Zee +jets channel of the inclusive jet multiplicity and the PT of the leading jet for MCFM and the fully-simulated corrected ALPGEN data. The errors on the MCFM predictions result from the PDF uncertainty and from the errors of the non-perturbative effect corrections. The errors on the ALPGEN sample include all the statistical and systematic uncertainties (JES 5%).

  • Inclusive Jet Multiplicity (.eps)(.png):
    Res_Njet_Reco.png

Statistical and Systematic Limitations

Uncertainty on the ratio of the measurement and the theory for the inclusive jet cross-section and the PT of the leading jet for Zee +jets process.

  • Uncertainty on the inclusive jet cross-section (.eps)(.png):
    JES_Error_All.png

  • Uncertainty on the PT of the leading jet (.eps)(.png):
    JES_Pt_Error_All.png

- EsterSegura - 29 Jul 2008

Topic attachments
I Attachment History Action Size Date Who Comment
Unknown file formateps 10njetsmcfmtruth.eps r1 manage 10.1 K 2008-07-30 - 20:00 EsterSegura  
PNGpng 10njetsmcfmtruth.png r1 manage 12.3 K 2008-07-30 - 20:00 EsterSegura  
Unknown file formateps 11lead2jettruthmcfm.eps r1 manage 11.7 K 2008-07-30 - 19:59 EsterSegura  
PNGpng 11lead2jettruthmcfm.png r1 manage 13.4 K 2008-07-30 - 19:58 EsterSegura  
Unknown file formateps 11leadjettruthmcfm.eps r1 manage 14.1 K 2008-07-30 - 19:58 EsterSegura  
PNGpng 11leadjettruthmcfm.png r1 manage 14.9 K 2008-07-30 - 19:57 EsterSegura  
Unknown file formateps 12invmass_new81101.eps r1 manage 17.9 K 2008-07-29 - 19:32 EsterSegura invmass Zmumu eps
PNGpng 12invmass_new81101.png r1 manage 13.2 K 2008-07-29 - 19:20 EsterSegura color
Unknown file formateps 12jespterrorcrossectionsym.eps r1 manage 14.6 K 2008-07-30 - 19:24 EsterSegura  
PNGpng 12jespterrorcrossectionsym.png r1 manage 13.4 K 2008-07-30 - 19:24 EsterSegura  
Unknown file formateps 12njets_new81101.eps r1 manage 12.7 K 2008-07-29 - 19:33 EsterSegura  
PNGpng 13jeserror_njets.png r1 manage 12.3 K 2008-07-30 - 19:10 EsterSegura  
PNGpng 13jespterror.png r1 manage 14.8 K 2008-07-30 - 19:09 EsterSegura  
Unknown file formateps 14jes_njets.eps r1 manage 10.2 K 2008-07-30 - 19:36 EsterSegura  
PNGpng 14jes_njets_new.png r1 manage 18.7 K 2008-07-30 - 19:36 EsterSegura  
Unknown file formateps 14jeserror_njets.eps r1 manage 9.3 K 2008-07-30 - 19:07 EsterSegura  
Unknown file formateps 14jespterror.eps r1 manage 14.5 K 2008-07-30 - 19:08 EsterSegura  
Unknown file formateps AlpJpt0CorrLin.eps r1 manage 18.8 K 2008-07-30 - 17:18 EsterSegura .eps
PNGpng AlpJpt0CorrLin.png r1 manage 19.7 K 2008-07-30 - 17:14 EsterSegura Comparison of the distribution of the PT of the leading jet for the generated Monte Carlo and for the recontructed quantities without any correction, after the corrections for electron triggering and reconstruction and after applying in addition the jet-re
Unknown file formateps AlpJpt1CorrLin.eps r1 manage 17.1 K 2008-07-30 - 17:18 EsterSegura  
PNGpng AlpJpt1CorrLin.png r1 manage 20.3 K 2008-07-30 - 17:15 EsterSegura Comparison of the distribution of the PT of the 2nd leading jet for the generated Monte Carlo and for the recontructed quantities
Unknown file formateps Ana_Jpt0.eps r1 manage 15.8 K 2008-07-29 - 20:04 EsterSegura  
PNGpng Ana_Jpt0.png r1 manage 15.6 K 2008-07-29 - 19:56 EsterSegura PT leading jet distribution for signal+backgrounds
Unknown file formateps Ana_Jpt1.eps r1 manage 15.6 K 2008-07-29 - 20:05 EsterSegura  
PNGpng Ana_Jpt1.png r1 manage 16.0 K 2008-07-29 - 19:57 EsterSegura PT 2nd leading jet for signal+backgrounds
Unknown file formateps Ana_Minv1.eps r1 manage 19.9 K 2008-07-29 - 20:05 EsterSegura  
PNGpng Ana_Minv1.png r1 manage 18.1 K 2008-07-29 - 19:58 EsterSegura Invariant Mass (e,e) for signal + background
Unknown file formateps Ana_Njet.eps r1 manage 12.2 K 2008-07-29 - 20:06 EsterSegura  
PNGpng Ana_Njet.png r1 manage 13.4 K 2008-07-29 - 19:58 EsterSegura Inclusive jet cross-section (signal+background)
Unknown file formateps C4_corr_all_jpt.eps r1 manage 11.5 K 2008-07-30 - 19:45 EsterSegura  
PNGpng C4_corr_all_jpt.png r1 manage 18.9 K 2008-07-30 - 19:44 EsterSegura  
Unknown file formateps C4_corr_frag_jpt.eps r1 manage 11.5 K 2008-07-30 - 19:44 EsterSegura  
PNGpng C4_corr_frag_jpt.png r1 manage 17.9 K 2008-07-30 - 19:43 EsterSegura  
Unknown file formateps Ejdr_All.eps r1 manage 22.1 K 2008-07-30 - 18:16 EsterSegura  
PNGpng Ejdr_All.png r1 manage 20.9 K 2008-07-30 - 18:16 EsterSegura deltaR (electron, jet)
Unknown file formateps Eldr_All.eps r1 manage 26.0 K 2008-07-30 - 18:55 EsterSegura  
PNGpng Eldr_All.png r1 manage 21.7 K 2008-07-30 - 18:17 EsterSegura deltaR (electron, electron)
Unknown file formateps JES_Error_All.eps r1 manage 13.1 K 2008-07-30 - 17:45 EsterSegura .eps
PNGpng JES_Error_All.png r1 manage 20.7 K 2008-07-30 - 17:43 EsterSegura .png
Unknown file formateps JES_Pt_Error_All.eps r1 manage 35.4 K 2008-07-30 - 17:46 EsterSegura  
PNGpng JES_Pt_Error_All.png r1 manage 27.7 K 2008-07-30 - 17:50 EsterSegura  
Unknown file formateps Res_Jpt0_Reco.eps r1 manage 15.2 K 2008-07-30 - 17:32 EsterSegura  
PNGpng Res_Jpt0_Reco.png r1 manage 15.7 K 2008-07-30 - 17:45 EsterSegura  
Unknown file formateps Res_Njet_Reco.eps r1 manage 11.7 K 2008-07-30 - 17:33 EsterSegura  
PNGpng Res_Njet_Reco.png r1 manage 14.7 K 2008-07-30 - 17:33 EsterSegura  
PNGpng SM_invmass_new81101.png r1 manage 13.4 K 2008-07-29 - 19:16 EsterSegura Invariant Mass (mu,mu) for signal + background
PNGpng SM_njets_new81101.png r1 manage 10.4 K 2008-07-29 - 19:17 EsterSegura Inclusive jet cross-section (signal+background)
Unknown file formateps SM_pt2leadjetbgdpythiaFactor.eps r1 manage 14.9 K 2008-07-29 - 19:34 EsterSegura  
Unknown file formateps SM_ptleadjetbgdpythiaFactor.eps r1 manage 15.9 K 2008-07-29 - 19:33 EsterSegura  
PNGpng SMpt2leadjetbgdpythiaFactor.png r1 manage 13.3 K 2008-07-29 - 19:19 EsterSegura PT 2nd leading jet for signal+backgrounds
PNGpng SMptleadjetbgdpythiaFactor.png r1 manage 13.4 K 2008-07-29 - 19:19 EsterSegura PT leading jet distribution for signal+backgrounds
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