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Diphoton & MET Optimization Plan for Initial 5fb-1 Analysis

Outline of ongoing work to optimize the 5 fb-1 analysis, aiming to finalize signal selection by Dec 1. Work includes definitions, samples selection, significance measure, observables, and detailed optimization plan.

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Diphoton & MET Optimization Plan for Initial 5fb-1 Analysis

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  1. Plans for for Diphoton + MET 5fb-1 Optimization Bruce Schumm 22 Nov 2011 Following is an outline of work underway to optimize the 5 fb-1 analysis. The work is underway and we hope to have the signal selection completed by Dec 1.

  2. Some Definitions MET: Will have to stay with LocHadTopo for the optimization HT: Scalar sum of everything visible (no MET!); including leptons w/ appropriate overlap removal. Isolation: Looking to Penn/LaPlata. Please provide cone definition and recommended cut value.

  3. Optimization Samples W + n jets (n > 1), ttbar: Enough statistics to just look directly at the tight diphoton background rate. W + 1 jet, W + gamma: We will choose events with one tight photon and one medium electron and scale this by e   fake rate (1/0.07) QCD: Start with single loose-tight photon control sample, scaled to 5x the 1 fb-1 low-MET diphoton spectrum. To avoid background biases, for final optimization use MET distribution of events with two or more 50 GeV jets.

  4. Optimization Figure of Merit We plan to separate the diphoton sample into three categories: 0, 1, and 2 conversions. We will construct the figure of merit by adding together three likelihoods (one for each category) of the form (s-b)ln(1 + s/b) - s

  5. Optimization Observables • We propose to do two-ish separate analyses: • MET only; (Mg,MB) = (900,880) (degenerate point) • A’) MET only; SPS8 with  = 170 • B) MET + HT; (Mg,MB) = (900,50) • Several different treatments of conversions: • All conversions together vs. separate categories • Remove conversion if matches to • medium electron • electron with any pixel activity

  6. Other Optimization Observables MET,min – MC plus scans of high MET events suggest discriminating power ET – have always taken lowest value allowed by trigger; have never tried to optimize M (?) – MC suggests discriminating power; may be redundant with other variables.

  7. Optimization Plan • Look for more optimal ET cut w/ existing analysis (Annecy; almost done) • Look at separate conversion categories, rejecting conversions w/ medium electrons or pixel activity (UCSC; almost done) • Choose optimal isolation strategy based on MC and e samples (Penn/LaPlata; almost done) • Optimize MET,  for (900,850) and SPS8 points • Optimize MET, HT,  for (900,50) point • See if M provides any additional discrimination (time permitting) • Finish up by Dec 1.

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