Overview of Inclusive Electrons Analysis with early data


CDF experience

With CDF run 1 data, from 1988-1989, Luminosity of $\sim 4 pb^{-1}$ the results were:
  • Background: $17\pm 3\%$ conversion, $17\pm 5\%$ hadron
  • cc fraction extracted using ptrel: $20\pm 10\%$
  • electron efficiency from MC: $60\pm 10\%$ ($30\pm5\%$) at 10 (25 GeV)
  • decreasing due to e/p and hadronic energy leakage cuts
  • Total systematic error ~27%

CDF paper on inclusive electrons

Ingredients for the analysis

Data samples

  • Mainly performance DPDs to be able to tune cuts for non-isolated electrons.
  • Trigger: e10_medium
  • Control Samples:
    • Minimum Bias and Jet samples for background studies
    • Photon and Muon triggers, plus e5_loose for trigger studies
    • Muon sample for b "tag and probe" (?)
  • Monte Carlo samples:
    • b and c quarks
    • Drell-Yan
    • Z and W
    • Jets and Minimum Bias for background

The produced samples for 10TeV and those still in production chain for 7TeV are shown in the following tables:

For 10 TeV
Dataset Nș of Events Cross section in $\mathbf{nb}$ generator filter efficiency effective Xsec in $\mathbf{nb}$ equiv luminosity in $\mathbf{pb^{-1}}$ scale for $\mathbf{1 pb^{-1}}$ New Dataset (15.X.Y reco)
mc08.106050.PythiaZee_1Lepton.merge.AOD.e347_s462_r635_t53 4937241 1.14014 9.60E-01 1.09453 4.51E+03 2.22E-04 mc09_valid.106050.PythiaZee_1Lepton.merge.AOD.e347_s564_s584_r810_r816
mc08.106020.PythiaWenu_1Lepton.merge.AOD.e352_s462_r635_t53 4798140 11.7544 8.80E-01 10.3439 4.64E+02 2.16E-03 mc09_valid.106020.PythiaWenu_1Lepton.merge.AOD.e352_s564_s584_r810_r816
mc08.105148.PythiaDrellYanLowM.merge.AOD.e347_s462_r635_t53 499546 311.79 8.60E-03 2.681 1.86E+02 5.37E-03 mc08.105148.PythiaDrellYanLowM.merge.AOD.e347_s462_s520_r808_r838 (**)
mc08.105722.PythiaB_bbe7X.merge.AOD.e401_s462_r635_t53 (*) 997701 1840.27 1.00 1840.27 5.42E-01 1.84E+00 mc09_valid.105722.PythiaB_bbe7X.merge.AOD.e401_s564_s584_r810_r816
mc08.106048.PythiaB_cce5X.merge.AOD.e401_s462_r635_t53 (*) 498725 3610.48 1.00 3610.48 1.38E-01 7.24E+00 mc08.106048.PythiaB_cce5X.merge.AOD.e401_s462_s520_r808_r838 (**)
mc08.105802.JF17_pythia_jet_filter.merge.AOD.e347_s462_r635_t53 9838290 1453600 7.06E-02 102624.16 9.59E-02 1.04E+01 mc09_valid.105802.JF17_pythia_jet_filter.merge.AOD.e347_s585_s582_r812_r814
mc08.105807.JF35_pythia_jet_filter.merge.AOD.e359_s462_r635_t53 5758201 75221.3 1.39E-01 10418.15 5.53E-01 1.81E+00 mc08.105807.JF35_pythia_jet_filter.merge.AOD.e359_s462_s520_r808_r838 (**)
mc08.105814.JF70_pythia_jet_filter.merge.AOD.e372_s462_r635_t53 997189 4700.67 1.99E-01 934.49 1.07E+00 9.37E-01 mc08.105814.JF70_pythia_jet_filter.merge.AOD.e372_s462_s520_r808_r838 (**)

(*)No cross section information available in AMI for these samples. The cross section was taken from the log files, and the value returned is already corrected for generator filtering efficiency (from PythiaB); therefore the filtering efficiency to be applied is 1.

The same generated events have been re-simulated and re-reconstructed with a newer release, the new datasets are shown on the last column on the right, except those marked by (**) which are only re-reconstructed, not re-simulated (s520 is from merging HITS files).

For 7 TeV
The samples being produced for 7 TeV collisions are shown in the table below. The vector boson samples are non filtered (as oposed to above --for 10 TeV-- with 1 lepton filter). The $c\bar{c}\rightarrow e X$ samples for this collision energy have a cut on either 7 or 3 GeV in the electron pT (no longer at 5 GeV as in the 10 TeV sample). Our cut should be at 10 GeV therefore we can use the former safely.

Dataset Nș of Events Cross section in $\mathbf{nb}$ generator filter efficiency effective Xsec in $\mathbf{nb}$ equiv luminosity in $\mathbf{pb^{-1}}$ scale for $\mathbf{1 pb^{-1}}$ Production status
mc09_7TeV.106046.PythiaZee_no_filter.merge.AOD.e468_s624_s633_r1085_r1113 4690460 0.851 1.0 0.851 5.51E+03 1.81E-04 Done
mc09_7TeV.106050.PythiaZee_1Lepton.merge.AOD.e468_s624_s633_r1085_r1113 299974 0.851 9.707E-01 0.826 3.63E+02 2.75E-03 Done
mc09_7TeV.106043.PythiaWenu_no_filter.merge.AOD.e468_s624_s633_r1085_r1113 6999245 8.894 1.0 8.894 7.87E+02 1.27E-03 Done
mc09_7TeV.106020.PythiaWenu_1Lepton.merge.AOD.e468_s624_s633_r1085_r1113 997877 8.928 8.711E-01 7.777 1.38E+02 7.25E-03 Done
mc09_7TeV.105148.PythiaDrellYanLowM.merge.AOD.e505_s624_s633_r1114_r1113 999937 179.63 1.341E-02 2.409 4.15E+02 2.41E-03 Done
$b\bar{b}$ and $c\bar{c}$
mc09_7TeV.105722.PythiaB_bbe7X.merge.AOD.e505_s624_s633_r1114_r1113 3991441 1760 1.0 1760 2.27E+00 4.41E-01 Done
mc09_7TeV.105721.PythiaB_cce7X.merge.AOD.e511_s703_s730_r1115_r1113 3977108 896.9 1.0 896.9 4.43E+00 2.26E-01 Done
mc09_7TeV.105724.PythiaB_bbe3X.merge.AOD.e511_s703_s730_r1115_r1113 3994585 18150 1.0 18150 2.20E-01 4.54E+00 Done
mc09_7TeV.105723.PythiaB_cce3X.merge.AOD.e511_s703_s730_r1115_r1113 3998379 19390 1.0 19390 2.06E-01 4.85E+00 Done
mc09_7TeV.105802.JF17_pythia_jet_filter.AOD.e505_s624_s633_r1114_r1113 9964045 1147580 8.623E-02 98957 1.01E-01 9.93E+00 Done
mc09_7TeV.105807.JF35_pythia_jet_filter.AOD.e505_s624_s633_r1114_r1113 4998432 54838 1.573E-01 8626 5.79E-01 1.73E+00 Done
mc09_7TeV.105001.pythia_minbias.merge.AOD.e517_s745_s746_r1098_r1113 3370686 48445000 1.0 48445000 6.96E-05 1.44E+04 Done
PowHeg NLO $b\bar{b}$ and $c\bar{c}$
mc09_7TeV.108330.BBbar_PowHeg_Jimmy.merge.AOD.e588_s765_s767_r1305_r1306 294706 220200 0.00571 1258      
mc09_7TeV.108332.CCbar_PowHeg_Jimmy.merge.AOD.e583_s765_s767_r1305_r1306 303451 3668000 0.000395 1449      
mc09_7TeV.108331.BBbar_PowHeg_Pythia.merge.AOD.e583_s765_s767_r1305_r1306 299957 220200 0.00918 2021      
mc09_7TeV.108333.CCbar_PowHeg_Pythia.merge.AOD.e583_s765_s767_r1305_r1306 299361 3668000 0.000436 1599      

New reconstruction means configTag=_r1085_r1113 (AtlasProduction-, same as data reprocessing) and the older reconstruction refers to configTag=_r1064_r1051 (AtlasProduction- For details on the configuration look here.

The Drell-Yan sample listed considers a $m_{z}$ range between $1GeV-60GeV$ and has a lepton filter $p_{T}>3GeV$, $|\eta|<2.7$ and requires at least 2 leptons. In addition there are new Drell-Yan samples which divide the events into Low mass ($8GeV-15GeV$) with electron $p_{T}>3GeV$, $|\eta|<2.7$ requiring at least one lepton is dataset mc09_7TeV.108322.PythiaDrellYanLowM_ee3.merge.AOD.e518_s745_s746_r1098_r1113 ; and the second sample with "Medium" mass ($15GeV-60GeV$) and without lepton filter is dataset mc09_7TeV.108320.PythiaDrellYan_ee.merge.AOD.e518_s745_s746_r1098_r1113.

The PythiaB cross sections are not in AMI but I got them from Borut and Junji via email (they should be posted to AMI eventually).

The generator lepton filter in the samples mc09_7TeV.106050.PythiaZee_1Lepton and mc09_7TeV.106020.PythiaWenu_1Lepton requires at least 1 lepton with $p_T>0 MeV$ and $|\eta|<2.8$.

Event selection

Acceptance: Estimate number of events expected per $pb^{-1}$, starting from generation level, for 10 TeV and 7 TeV and benchmark inclusive electron spectra with loose, medium and tight electron selection with rel15 reconstruction for 10 TeV (mc08) and for 7 TeV (mc09), including the background (JFxx and Jx samples)

Expected electron spectrum

For 10 TeV LHC collisions the expected electron spectrum (origin classified from MC truth) is shown in the figure.

All Electrons 1pb II gev stack inv.png
Distribution of electron p_T for 10 TeV collisions.

The datasets used and the associated generator efficiency and corrections are shown on the table above. Other electron distributions are here.

Electron Identification optimization with data and MC

Background estimation

Background are Jet fakes, i.e. hadrons overlapping with pi0 or photon, charge exchange, EM showering; and photon conversions or pi0 decays that were not identified.

Sample Composition

Estimate fractions of background and b/c (or b, c), W/Z

Additional criteria for inclusive b cross section measurement

Event selection for b

Optimisation of isEM cuts, to be able to separate W, Z and Drell-Yan "foreground".

Efficiencies measurement

These are necessary corrections in order to compute the cross section:

  • Trigger efficiency wrt offline, possible to estimate with data
  • Offline selection efficiency: need to rely in MC and data

Background estimate

Systematical uncertainties (theoretical and experimental)

(references: Tevatron first b cross-section data, Tevatron b-hadron cross-section, Hera implications for LHC 2006, Hera implications for LHC 2009 )

EGamma Group Sharepoint

UnigeEgamma Sharepoint

EGamma group MC production for 7TeV and 900GeV


Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng All_Electrons_1pb_II_gev_stack_inv.png r1 manage 94.6 K 2010-02-03 - 20:09 ClemenciaMora Distribution of electron p_T for 10TeV collisions
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Topic revision: r22 - 2010-11-15 - ClemenciaMora
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