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Babar Physics Jamboree University of Cincinnati 25 April 2010

Measurement of D* + Natural Line Width Carol Fabby Rolf Andreassen, Mikhail Dubrovin, Zach Huard, Brian Meadows, Mike Sokoloff University of Cincinnati. Babar Physics Jamboree University of Cincinnati 25 April 2010. What is Known About D* Width?. Previous studies

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Babar Physics Jamboree University of Cincinnati 25 April 2010

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  1. Measurement ofD*+ Natural Line WidthCarol Fabby Rolf Andreassen, Mikhail Dubrovin,Zach Huard, Brian Meadows,Mike Sokoloff University of Cincinnati Babar Physics Jamboree University of Cincinnati 25 April 2010

  2. What is Known About D* Width? • Previous studies • ACCMOR: • 90% CL upper limit to Γ of 131 keV • Poor statistics • CLEO: • 1st measurement Γ = [96 ± 4 (stat) ± 22 (syst)] keV • Good resolution, poor statistics • Current measure of width: • BaBar Release 24 data • Decay channel D*+→ D0πs+ D0→ K-π+ • Good resolution and good statistics Carol Fabby BaBar Physics Jamboree University of Cincinnati 25 April 2010

  3. Event Selection • For high quality tracks, good resolution and to remove background: • πs DCH Hits > 12 • Kaon DCH Hits > 20 • Pion DCH Hits > 20 • Makes requirements on number of hits to have well measured tracks: • Pion SVT OK • Kaon SVT OK • Slow Pion SVT OK Carol Fabby BaBar Physics Jamboree University of Cincinnati 25 April 2010

  4. Event Selection • To eliminate electron mis-identification from D*0→ D0π0π0 →γ γ , γ e + e -) • πs , veto on IsGammaConversion • πs , veto on IsDalitzConversion • Overall general cut, to eliminate e - • -3 < πs Pull for dE/dx (DCH) < 2 • -3 < πs Pull for dE/dx (SVT) < 2 Carol Fabby BaBar Physics Jamboree University of Cincinnati 25 April 2010

  5. Carol Fabby BaBar Physics Jamboree University of Cincinnati 25 April 2010

  6. Fitting Method • Use Monte Carlo to determine resolution function • Signal: 3 Gaussians with independent means and widths • Background: Threshold (Argus function) • Real Data Signal • Signal: Breit-Wigner convolved with [(MC Resolution) x (1 + ε)] • Background: Threshold (Argus Function) • Carol Fabby BaBar Physics Jamboree University of Cincinnati 25 April 2010

  7. Examples of Typical Fits and Pull Distribution Plots • Carol Fabby BaBar Physics Jamboree University of Cincinnati 25 April 2010

  8. ε • Carol Fabby BaBar Physics Jamboree University of Cincinnati 25 April 2010

  9. Summary • Results Γ = [101 ± 1 (stat) ± 22 (syst)] keV • Future Analysis • Look at variation of lab momentum • Determine variation due to track quality • Evaluate cause of systematic variation observed in pull plots • Try different BW shapes • Carol Fabby BaBar Physics Jamboree University of Cincinnati 25 April 2010

  10. BACK-UP SLIDES • Carol Fabby BaBar Physics Jamboree University of Cincinnati 25 April 2010

  11. SVTOK • Bitmask • >2 hits in r/phi-view (at least 1 hit in layer 1-3) • >2 hits in z-view (at least 1 hit in layer 1-3) • >6 hits total (r/phi + z view) • Carol Fabby BaBar Physics Jamboree University of Cincinnati 25 April 2010

  12. Inset - Mid K π Range - Log • Carol Fabby BaBar Physics Jamboree University of Cincinnati 25 April 2010

  13. Variables • Carol Fabby BaBar Physics Jamboree University of Cincinnati 25 April 2010

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