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Drell-Yan Task: Introduction

Drell-Yan Task: Introduction. Dimitri Bourilkov University of Florida Drell-Yan EWK Meeting 1, CMS, April 28, 2008. Introduction. Cumulative plots. LHC is a high mass di-lepton factory Already with ~100 pb -1 @ 14 TeV we will be probing regions @ 800+ GeV

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Drell-Yan Task: Introduction

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  1. Drell-Yan Task: Introduction Dimitri Bourilkov University of Florida Drell-Yan EWK Meeting 1, CMS, April 28, 2008

  2. Introduction Cumulative plots • LHC is a high mass di-lepton factory • Already with ~100 pb-1 @ 14 TeV we will be probing regions @ 800+ GeV • Be ready to move to high masses immediately after demonstrating the Z peak performance Drell-Yan Task: Introduction

  3. Drell-Yan Task • Scope: study ee, μμ, eμ above (at startup – also below) the Z peak; ? • Bridge the gap between Z - high mass • Measure cross sections and (later) AFB • Existing work: • Use results from W/Z ee and μμ groups as a baseline; augment with high mass studies from HEEP and TeVmu groups • For 1-100 pb-1 extrapolation to higher masses will require MC and (to limited extent due to low event rates) data driven methods. Use ratios where possible. The residual dependence on pT and mass will need simulation inputs • Combining ee and μμ (and eμ) results - vital crosschecks: • cross sections should be ~ equal • same for DY mass spectra (slope), ratios to Z, etc.; as the resolutions for ee and μμ have opposite pT dependence, this will provide an important handle • AFB @ Z, below Z and @ 100-200 GeV should be ~equal Drell-Yan Task: Introduction

  4. Efficiencies & Resolutions • Efficiencies from data: tag and probe • At Z: • trigger efficiencies • offline efficiencies • Higher mass: • can not go higher than <~ 250-300 GeV for 100 pb-1 due to        limited statistics • backgrounds can be difficult • Resolutions from data (pT, mass): • Fit Z mass spectrum: advanced • Momentum scale calibration • High mass: limited statistics, no peak; pT balancing for μ+μ-?!; leapfrog method for e+e- – how far can we go for lumi < 1fb-1? Drell-Yan Task: Introduction

  5. Backgrounds • MC studies progressing well (CSA07 soups) • Data driven methods for jet-jet backgrounds (for ee, μμ) • Top-pair background similar for e+e- andμ+μ- • Electrons: • machine background? • Muons: • cosmics: studies underway • machine background: • beam halo • neutrons? need more study Drell-Yan Task: Introduction

  6. Theory / Monte Carlo • Many things in common for ee and μμ • PDF uncertainties: well advanced • QCD corrections: • results with FEWZz @ NLO and NNLO • results with MC@NLO for NLO • QED ISR/FSR: studies progressing well • Genuine EWK corrections: theory calculations, no single MC generator but recent progress with MC@NLO + HORACE and HERWIG parton showering Drell-Yan Task: Introduction

  7. Signal Definition Nobs = L..  = acceptance .trigger .offline-reco • Standard: cross sections calculated in 4; acceptance calculated e.g. by MC • Alternative: define signal cross section to cover where we measure e.g. define CMS di-muon cross section with cut on both muons |μ1|<2.4 and |μ2|<2.4 • Can calculate directly in PYTHIA, HERWIG, FEWZz … • In this approach events with 1 generated muon || > 2.4 are just part of the background • Eliminates the acceptance calculation • Can publish two (sets of) cross sections: in CMS acceptance region and (different) extrapolations to 4 Drell-Yan Task: Introduction

  8. Drell-Yan Event Rates @ 10 TeV Rough estimate: no K-functions, no efficiency (ee OR μμ) The statistical errors on a normalization to the Z are shown in the table; the errors from PDF uncertainties are 4-8 % for the 500+ or 1000+ bins. For 10 pb-1 the DY background to new physics is negligible above 500 GeV, for 100 pb-1 above 1 TeV. Any statistically significant accumulation of events in these areas would signal new physics. Drell-Yan Task: Introduction

  9. Evolving Drell-Yan Tasks List

  10. Outlook • TWIKI page: evolving task list posted there – please sign in and add missed or “forgotten” tasks https://twiki.cern.ch/twiki/bin/view/CMS/TWikiEWKDrellYan • Hypernews - interested people can subscribe: hn-cms-ewk-drellyan@cern.ch • Drell-Yan provides tests of the Standard Model at highest momentum transfers (and soon after start-up will push into unexplored territory) • Irreducible background for high mass searches • Plenty to do before first collisions – feedback and volunteers most welcome • CSA07 samples available • Test and verify fast simulation for high energy electrons/muons by comparing to full simulation • Contacted groups active in Z and high mass analyses; received feedback from W/Z, HEEP, TeVmu, LPC di-lepton groups Drell-Yan Task: Introduction

  11. Backup Slides Drell-Yan Task: Introduction

  12. Normalization to Z Peak ‘Data’ @ 14 TeV Good agreement in ratios between PYTHIA with different PDFs and FEWZz in LO, NLO & NNLO Drell-Yan Task: Introduction

  13. PDF Uncertainties PYTHIA CTEQ6.1 @ 14 TeV • Mass [GeV] xsec [pb] PDF Uncertainty [%/100] CTEQ6.1 • Cross Section Xsec ratio to Z Xsec ratio toZ • Uncorrelated Correlated • 0040-0060 41.07933 + 0.067 - 0.079 + 0 - 0 + 0 - 0 • 0060-0080 29.11724 + 0.058 - 0.075 + 0 - 0 + 0 - 0 • 0080-0100 650.3979 + 0.053 - 0.073 + 0 - 0 + 0 - 0 • 0100-0120 20.91373 + 0.050 - 0.071 + 0.074 - 0.102 + 0.004 - 0.005 • 0120-0140 4.166503 + 0.047 - 0.067 + 0.071 - 0.100 + 0.010 - 0.010 • 0140-0160 1.773516 + 0.045 - 0.066 + 0.070 - 0.098 + 0.014 - 0.015 • 0160-0180 0.9442186 + 0.043 - 0.063 + 0.069 - 0.097 + 0.019 - 0.019 • 0180-0200 0.5534378 + 0.041 - 0.061 + 0.068 - 0.096 + 0.022 - 0.023 • 0200-0300 1.047500 + 0.040 - 0.058 + 0.067 - 0.093 + 0.030 - 0.030 • 0300-0400 0.2334509 + 0.038 - 0.053 + 0.066 - 0.090 + 0.042 - 0.040 • 0400-0500 0.7916863E-01 + 0.038 - 0.050 + 0.066 - 0.088 + 0.051 - 0.047 • 0500-0600 0.3307076E-01 + 0.039 - 0.049 + 0.066 - 0.088 + 0.058 - 0.053 • 0600-0700 0.1550730E-01 + 0.040 - 0.050 + 0.067 - 0.089 + 0.064 - 0.057 • 0700-0800 0.7982878E-02 + 0.042 - 0.051 + 0.068 - 0.089 + 0.071 - 0.062 • 0800-0900 0.4451912E-02 + 0.043 - 0.052 + 0.069 - 0.090 + 0.075 - 0.066 • 0900-1000 0.2634348E-02 + 0.045 - 0.054 + 0.070 - 0.091 + 0.080 - 0.069 • 1000-1500 0.4326681E-02 + 0.049 - 0.058 + 0.072 - 0.094 + 0.090 - 0.076 • 1500-2000 0.6327142E-03 + 0.061 - 0.068 + 0.081 - 0.100 + 0.109 - 0.088 • 2000-2500 0.1307343E-03 + 0.077 - 0.079 + 0.094 - 0.108 + 0.131 - 0.100 • 2500-3000 0.3304343E-04 + 0.101 - 0.093 + 0.114 - 0.118 + 0.158 - 0.114 • 3000-3500 0.9280736E-05 + 0.128 - 0.110 + 0.139 - 0.132 + 0.186 - 0.133 • 3500-4000 0.2832010E-05 + 0.166 - 0.133 + 0.175 - 0.152 + 0.225 - 0.158 • 4000-4500 0.9166083E-06 + 0.208 - 0.160 + 0.215 - 0.176 + 0.267 - 0.185 • 4500-5000 0.3097030E-06 + 0.267 - 0.189 + 0.272 - 0.203 + 0.330 - 0.214 • 5000-5500 0.1052451E-06 + 0.340 - 0.220 + 0.344 - 0.232 + 0.407 - 0.246 • 5500-6000 0.3560790E-07 + 0.434 - 0.251 + 0.437 - 0.261 + 0.506 - 0.277 Drell-Yan Task: Introduction

  14. PDF Uncertainties PYTHIA MRST2006nnlo @ 14 TeV • Mass [GeV] xsec [pb] PDF Uncertainty [%/100] MRST2006nnlo • Cross Section Xsec ratio to Z Xsec ratio toZ • Uncorrelated Correlated • 0040-0060 43.31540 + 0.022 - 0.024 + 0 - 0 + 0 - 0 • 0060-0080 31.37652 + 0.021 - 0.024 + 0 - 0 + 0 - 0 • 0080-0100 711.2241 + 0.020 - 0.024 + 0 - 0 + 0 - 0 • 0100-0120 22.31959 + 0.018 - 0.023 + 0.027 - 0.034 + 0.001 - 0.002 • 0120-0140 4.445462 + 0.017 - 0.022 + 0.026 - 0.033 + 0.004 - 0.004 • 0140-0160 1.873783 + 0.015 - 0.022 + 0.025 - 0.032 + 0.006 - 0.006 • 0160-0180 0.9922243 + 0.014 - 0.021 + 0.025 - 0.032 + 0.007 - 0.007 • 0180-0200 0.5824341 + 0.013 - 0.020 + 0.024 - 0.031 + 0.008 - 0.009 • 0200-0300 1.089530 + 0.012 - 0.018 + 0.023 - 0.030 + 0.011 - 0.011 • 0300-0400 0.2444447 + 0.010 - 0.016 + 0.022 - 0.029 + 0.015 - 0.015 • 0400-0500 0.8363874E-01 + 0.009 - 0.014 + 0.022 - 0.028 + 0.018 - 0.018 • 0500-0600 0.3411233E-01 + 0.010 - 0.013 + 0.022 - 0.027 + 0.021 - 0.021 • 0600-0700 0.1597897E-01 + 0.010 - 0.013 + 0.022 - 0.027 + 0.023 - 0.023 • 0700-0800 0.8369605E-02 + 0.012 - 0.013 + 0.023 - 0.027 + 0.026 - 0.024 • 0800-0900 0.4557460E-02 + 0.013 - 0.014 + 0.024 - 0.028 + 0.028 - 0.026 • 0900-1000 0.2710390E-02 + 0.015 - 0.015 + 0.025 - 0.028 + 0.031 - 0.028 • 1000-1500 0.4430216E-02 + 0.020 - 0.018 + 0.029 - 0.030 + 0.036 - 0.031 • 1500-2000 0.6344162E-03 + 0.036 - 0.026 + 0.041 - 0.036 + 0.050 - 0.038 • 2000-2500 0.1321555E-03 + 0.059 - 0.039 + 0.062 - 0.046 + 0.070 - 0.047 • 2500-3000 0.3309892E-04 + 0.087 - 0.054 + 0.089 - 0.059 + 0.096 - 0.059 • 3000-3500 0.9441089E-05 + 0.123 - 0.070 + 0.125 - 0.074 + 0.131 - 0.073 • 3500-4000 0.2948886E-05 + 0.166 - 0.087 + 0.167 - 0.091 + 0.172 - 0.089 • 4000-4500 0.9577241E-06 + 0.210 - 0.104 + 0.211 - 0.107 + 0.215 - 0.105 • 4500-5000 0.3230551E-06 + 0.253 - 0.120 + 0.254 - 0.123 + 0.257 - 0.120 • 5000-5500 0.1090954E-06 + 0.294 - 0.138 + 0.294 - 0.140 + 0.298 - 0.137 • 5500-6000 0.3693165E-07 + 0.327 - 0.154 + 0.328 - 0.156 + 0.331 - 0.153 Drell-Yan Task: Introduction

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