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Dielectron Spectrum Analysis

Dielectron Spectrum Analysis. J. Leonard 16 Sept. 2009. Today. Action items from e-mail Identify which cut is causing the strange shape in mass and pt. Check all cuts in sequence one at a time till you find the cut that is a problem. See later slides

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Dielectron Spectrum Analysis

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  1. Dielectron Spectrum Analysis J. Leonard 16 Sept. 2009

  2. Today • Action items from e-mail • Identify which cut is causing the strange shape in mass and pt. • Check all cuts in sequence one at a time till you find the cut that is a problem. • See later slides • Though first try removing the isolation. Isolation looks like it might be the source of part of the problem. • Part of the problem, but only part -- see later slides • If it is the source of all the problems move to relative isolation. • Investigate relative isolation with a floor • Optimize final cuts • Probably we want to use tighter electron cuts.

  3. Signal efficiency vs. invariant mass at each step • Features appear separately • Fall-off at low end appears after 10-GeV pT cut • Peak and dip/plateau below peak start to appear after electron ID cuts (ii, in) • Dip and high-end fall-off more pronounced after isolation cuts • Efficiencies defined with respect to initial step

  4. Efficiency features: electron ID or isolation? • Main idea: • Switch electron ID and isolation steps • If features due mainly to electron ID, should not show up until electron ID step (after isolation step) • Features already present in isolation step (before electron ID) • Dip and high-end drop-off pronounced • Electron ID step reduces general efficiency, flattens area ~50 GeV • Efficiencies defined with respect to initial step

  5. Signal efficiency: electron ID • Plateau/peak structure appears with each cut (ii and in) separately • Possibility the problem is -dependent -- endcap vs barrel. To investigate • Efficiencies defined with respect to initial step

  6. Signal efficiency: isolation • Dip ~70 GeV appears clearly in ECAL-only curve • Drop-off at high end has no clear culprit • Efficiencies defined with respect to initial step

  7. Next Steps • Further investigate efficiency features • Analyze separately for barrel/endcap • See how eID/iso variables themselves vary with pT/invariant mass • Ask authors of Zee note if they’ve seen this issue or know anything about it • Investigate relative isolation • May help efficiency (especially at high end) • See what optimization algorithm from Zee note can do for us • What to optimize: S/B, or something else

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