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Outline Introduction and Motivation Method Event Selection Fitting Yield Extractions Systematics

HADRONIC BRANCHING FRACTIONS OF D 0 AND D + AND THE PRODUCTION CROSS SECTION AT THE (3770) RESONANCE. Outline Introduction and Motivation Method Event Selection Fitting Yield Extractions Systematics Results Conclusion and Summary. Batbold Sanghi, Purdue University

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Outline Introduction and Motivation Method Event Selection Fitting Yield Extractions Systematics

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  1. HADRONIC BRANCHING FRACTIONS OF D0 AND D+ AND THE PRODUCTION CROSS SECTION AT THE (3770) RESONANCE • Outline • Introduction and Motivation • Method • Event Selection • Fitting • Yield Extractions • Systematics • Results • Conclusion and Summary Batbold Sanghi, Purdue University for the CLEO collaboration

  2. Introduction • CLEO-c, in a pilot run, has accumulated 57.2 pb-1. with this data, we present a preliminary measurement of absolute branching fractions and cross section. We use double tagging technique pioneered by MARK III. • branching fractions: and are reference branching fractions. • Determine other branching fractions • Reduce systematics when extracting CKM matrix elements • cross section • Precise measurement since many systematic errors canceled. RESULTS ARE PRELIMINARY

  3. Using double tags to measure and K- + e- e- e+ e+ p- p- K+ K+ Double tagged D Single tagged D • Single and double tags give and • Use 3 modes : , , • Use 2 modes : ,

  4. Using double tags to measure and • and yields fitted separately. • 10 single tag yields and 13 double tag yields. • Perform fits • Parameters: 5 branching ratio and and • Yields corrected by backgrounds and crossfeeds • The fit includes statistical and systematic uncertainties. • Statistical errors for efficiencies, yields, and background subtractions • Correlated and uncorrelated systematic errors • Some systematic errors for and completely cancelled • and in this approximation,

  5. Selection criteria • Two key variables(D0K-+ as an example) • 0 • 3.0 σ mass cut for 0mass • Shower energy > 30MeV • 0 • 3.0 σ mass cut for 0mass • Shower energy > 30MeV • Track selection criteria: • Track quality criteria • Hadronic PID criteria are based on • the dE/dX information • the RICH information • Ks • 3.0 σ mass cut for Ksmass • Additional cuts • Mode dependent cuts • Lepton veto to reject cosmics, radiative bhabhas and pairs when an event has two tracks. • Best candidate selection for single tag modes • Choose the entry with the smallest • Best candidate selection for double tag modes • Choose the entry with the smallest

  6. Single tag fitting • Signal MC without ISR: • fit with Argus+Gaus+wide bif. Gaus • Ratio between widths of Gaus and wide bif. Gauss • Ratio between areas of Gaus and wide bif. Gaus • Generic MC(no ISR) • fit with Argus+Gau+wide bif. Gaus • Fix the above parameters • Signal MC with ISR: • fit with Argus+Crys.Ball+ wide bif. Gau • Data • fit with Argus+Crys.Ball+ wide bif. Gau Signal MC with ISR Signal MC without ISR DD bar MC Data Mbc(GeV) Mbc(GeV)

  7. Double tag fitting • Double tag sample • . • Signal components • A a diagonal Crys.BallGau : • a wide Gaussian • Background components • A diagonal Argus function • two Argus functions. M2(GeV) M1(GeV) M2(GeV) M1(GeV) M1(GeV)

  8. Single and Double tag efficiency within statistical uncertainty PRELIMINARY

  9. Generic MC Yields • Check the technique for yield extraction and branching ratio fit • Samples : (10data),CONT and RR MC. • Statistical errors (3 times smaller than for data) • crossfeed and background contributions PRELIMINARY

  10. Generic Monte Carlo Fit Result • The yields corrected by crossfeed and background contributions. • Statistical errors for yields(3 times smaller than for data) • Systematic errors (substantially smaller than for data) • Fitted values reproduced input variables. PRELIMINARY

  11. Data Yields • Single tag • 44260 neutral single tags and 17360 charged single tags • Double tag • Poor statistics for some double tag modes • 2480 neutral double tags and 502 charged double tags PRELIMINARY

  12. Systematics • Currently dominated by tracking efficiency systematics. • Most systematics will improve with further study. PRELIMINARY

  13. Data Fit Result • All branching fractions consistent with PDG averages(higher than) • Better agreement for ratio of branching fractions. • Statistical errors for branching fractions : 20-40% of total error(systematics limited) • Precise measurement for and (some systematic errors cancelled) *Our branching fractions are corrected by FSR. PDG values are not

  14. Cross Sections • Luminosity collected on : 57.2pb-1 • Cross section : • nb • nb • nb PRELIMINARY

  15. Summary • Cross sections : • nb • nb • nb • The preliminary results for reference branching fractions : • Many systematic uncertainties will be improved with further study. • more results from CLEO-c in the near future PRELIMINARY

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