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Dielectron Spectrum Analysis

Dielectron Spectrum Analysis. J. Leonard 7 Oct. 2009. Today. Action items from e-mail High pt and mass fall off caused by isolation cuts. Move to relative isolation with minimum value at low energy. Your previous cut values are probably a good value for the minimum value at low energy.

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Dielectron Spectrum Analysis

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  1. Dielectron Spectrum Analysis J. Leonard 7 Oct. 2009

  2. Today • Action items from e-mail • High pt and mass fall off caused by isolation cuts. Move to relative isolation with minimum value at low energy. Your previous cut values are probably a good value for the minimum value at low energy. • Wait until move to 3X for any optimization, after 2X note is done • Make delta R plot for events in barrel with pt<50GeV. With current definition of gen pt. For these events. Search for bug. Ignore rest if you find one • Found bug in R-matching • are these events radiating so strongly. Dont expect this to happen • plot gen level - gen level for different statuses. • plot reco level vs gen level before radiation • match to electrons that have the Z as a parent. • Still want to get mother information to understand invariant mass plot • Check the eta plot. • See later slides • New plots for two electrons Matt • For the second electrons in events above and below the Z peak what do the eta and pt distributions look like compared to in the peak. • Make curves for each region of mass you think is relevant. • Compare your denominator and numerator definitions for efficiency with Christos • Sasha Remake the barrel only plots with a cut of eta<1.0 • Push upsilon trigger note out separately

  3. Total efficiency of each selection step • Fraction of gen-level electrons (selected previously) passing each step as function of selected electron’s gen-level pT • Barrel + endcap

  4. Total efficiency of each selection step: barrel-only • Fraction of gen-level electrons (selected previously) passing each step as function of selected electron’s gen-level pT • Barrel only • Looks much better post-bugfix! No giant dip at low end

  5. Total efficiency of each selection step • Fraction of gen-level electrons (selected previously) passing each step as function of selected electron’s gen-level  • Barrel + endcap

  6. Efficiencies of steps wrt. previous step: vs  • Efficiencies of steps wrt. previous step • Both barrel and endcap shown

  7. Comparing gen-level Z/* and electrons: Minv spectrum • Left plot non-log-scale, right plot log-scale • Further investigation: looked at dump of particles in ten events • Usually at least one electron radiates a photon as FSR • In 2/10 events, this caused an electron energy change of >~few GeV • Enough to cause this effect? Still don’t know, but to find out . . . • Add mother/status information to ntuple in order to look at electrons from Z

  8. Next Steps • Add mother information to ntuple to select electrons from Z • Then see how efficiency/spectrum changes • Start putting together 22X analysis note with what I have • Highest priority! • Get template, add outline, plots

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