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Various progress in Z µ + µ -

Various progress in Z µ + µ -. EWK Dilepton meeting, 23.11.2010 Arie Bodek, Yeonsei Chung, Jiyeon Han Rochester University Alessio Bonato, Andrei Gritsan, Zijin Guo, Nhan Tran* Johns Hopkins University. Outline. A first look at MC and Data in CMS Features, comparison, implications

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Various progress in Z µ + µ -

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  1. Various progress in Zµ+µ- EWK Dilepton meeting, 23.11.2010 Arie Bodek, Yeonsei Chung, Jiyeon Han Rochester University Alessio Bonato, Andrei Gritsan, Zijin Guo, Nhan Tran* Johns Hopkins University

  2. Outline • A first look at MC and Data in CMS • Features, comparison, implications • Implications for analyses of Afb and sin2W • Plans and progress in Afb with event weighting http://indico.cern.ch/conferenceDisplay.py?confId=112949(N.T.) • Plans and progress in sin2W with likelihood method http://indico.cern.ch/conferenceDisplay.py?confId=113453(A. Gritsan) A report on various activities related to Zµ+µ-

  3. Data/MC: Kinematic distributions MC:/DYToMuMu_M-20_CT10_TuneZ2_7TeV-powheg-pythia/Fall10-START38_V12-v1 data: 35 pb-1 Basic plots match those shown elsewhere with reasonable agreement

  4. More MC plots Interesting acceptance effect resolution vs. eta resolution

  5. Afb in MC Effect seen last time… Full Y range 1 < |Y| < 2 Forward-backward asymmetry switches sign near Z peak More severe at greater Y

  6. Resolution and binning Let’s look at one specific mass bin… Reason for Afb sign flip Resolution with right-side tail, “artificial” due to binning

  7. Implications for event weighting Afb Reminder of the strategy: • Resolution/FSR and bin migration effects large (could increase bin size) • Solution: need to account for by including in weighting tables; FSR and “fast smear” at generator level, need to implement negative weighting Event weighting for dilution Pull corrections for detector effects raw Afb weighted Afb measured Afb Change strategy: Event weighting for dilution, FSR, resolution Pull corrections for remaining effects raw Afb weighted Afb measured Afb

  8. Resolution Resolution effects need to be understood for both likelihood technique (resolution convolution) and event weighting technique (fast smear for weighting) Fit with double Gaussian for both m and m2 resolution - technical reasons due to analytical convolution in likelihood approach

  9. Acceptance Flat acceptance not a good model, lose events at larger  Gen level (flat acceptance, ||<2.1), Reco level (||<2.1) Parametrize acceptance with polynomial fit (acceptance function)

  10. Implication for likelihood analysis • Recall, likelihood function over 3 observables (m,Y,cos) used in angular analysis and fitting of Weinberg angle, sin2W. • Analytical description involving • Parton-level cross-section • Parton distribution functions • Dilution • Acceptance - flat acceptance • Resolution - Gaussian smearing (No FSR) • Implement more realistic modeling of detector effects using MC for acceptance and resolution

  11. Resolution and acceptance 1D projections with flat acceptance and Gaussian smearing Y cos  m Now, implementing realistic resolution and acceptance *Fit under study

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