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Neutrino mass resolution study

Neutrino mass resolution study. Study Neutrino mass reconstruction in MC Study semi-leptonic B decays Recent reskim Use MC truth to identify B decay products Use (Ghit) MC matching to study reconstruction effects Identify which effects have the most impact on neutrino mass resolution

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Neutrino mass resolution study

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  1. Neutrino mass resolution study • Study Neutrino mass reconstruction in MC • Study semi-leptonic B decays • Recent reskim • Use MC truth to identify B decay products • Use (Ghit) MC matching to study reconstruction effects • Identify which effects have the most impact on neutrino mass resolution • Use Mini information to improve reconstruction • Work through effects in order of importance • Define event selection to remove ‘unrecoverable’ data • Status • Tooling-up mostly complete • Gutils package • Gtrack bugs identified and fixed or worked-around • Preliminary plots (without Reco matching) David Nathan Brown 1 Semi-leptonic recoil group 5 August, 2004

  2. 60% of skimmed generic B0 MC have a semi-leptonic B decay • Use GTrack (MC truth) P4 • Follow B decay to the first (prompt) long-lived particles • Neutrino mass2 computed as B P4 - S long-lived P4 David Nathan Brown 2 Semi-leptonic recoil group 5 August, 2004

  3. Prompt = not a decay product of a long-lived particle • Observable = long-lived - neutrinos • Measurable = Observable - neutral hadrons • Detectable = Measurable with crude detector acceptance David Nathan Brown 3 Semi-leptonic recoil group 5 August, 2004

  4. Next Step - study reco effects • Multiply-counted objects • loopers • ghosts • decays (mother + daughter) • split track-Emc • Material interactions (mother + daughters) • Lost particles • acceptance • Below momentum threshold • Material interaction • Resolution • Gaussian • Non-gaussian • merged decays • pat rec errors • inverted track direction • wrong decay point (for V0s) • Background • machine background tracks and clusters • PID error (wrong track mass) David Nathan Brown 4 Semi-leptonic recoil group 5 August, 2004

  5. Reconstruction Improvements • Tracking • Add Svt dE/dx as a momentum constraint on svt-only tracks • Add beamspot as a point on low-momentum tracks • Look for lost svt-only tracks using beamspot + 2 hits • Remove hits with bad timing or fit consistency using final Kalman fit • Merge (or eliminate) loopers and ghosts using full Kalman fit • Use track fit hypo chisq differences as a ‘last-resort’ PID • Neutrals • Associate multiple (splitoff) bumps to a single hadronic track • Identify events with neutral hadrons using Ifr + Emc information • Other • Use material map to improve Brem correction • Reconstruct nuclear interactions • Reconstruct single-photon gamma conversions David Nathan Brown 5 Semi-leptonic recoil group 5 August, 2004

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