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Ron Poling School of Physics and Astronomy College of Science and Engineering

D + Leptonic and D 0 Semileptonic Decays First Results from BESIII. Ron Poling School of Physics and Astronomy College of Science and Engineering University of Minnesota. Window on Weak and Strong Physics. Leptonic Decay.

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Ron Poling School of Physics and Astronomy College of Science and Engineering

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  1. D+Leptonic and D0Semileptonic Decays First Results from BESIII Ron Poling School of Physics and Astronomy College of Science and Engineering University of Minnesota

  2. Window on Weak and Strong Physics Leptonic Decay • Decay constant fD incorporates the strong interaction effects (wave function at the origin) • Use charm leptonic decays to validate theory (LQCD) and apply to B mixing, which requires fB • Multiple tests with charm: fD, fDs (esp. ratios) • Sensitivity to New Physics Ron Poling - ICHEP 2012

  3. Window on Weak and Strong Physics Semileptonic Decay • Use Strong Interaction theory (LQCD) for form factor, extract CKM • Use other measurements and unitarity for CKM and test theory • Theoretical uncertainties can be reduced in determinations of |Vub| if FF calculations can be validated with charm • Multiple tests available, semileptonicD decays to pseudoscalar mesons are cleanest Ron Poling - ICHEP 2012

  4. Window on Weak and Strong Physics • Widths of mixing and |Vub| bands will be reduced as charm validates LQCD • Long-term goal: Over-constrain CKM and search for New Physics Ron Poling - ICHEP 2012

  5. Charm Physics at Threshold • At ψ(3770) charm production is and • Fully reconstruct about 15% of D decays • Hadronic tag on one side gives “beam” of D0 or D+ on the other side for leptonic/semileptonic studies. Neutrino is reconstructed from missing energy and momentum Ron Poling - ICHEP 2012

  6. BESIII at BEPCII • Comparable capabilities to CLEO-c, plus muon ID • The big advantage: BEPCII is a two-ring machine designed for charm • Design (achieved) luminosity at ψ(3770): 1 (0.65) x 1033 Ron Poling - ICHEP 2012

  7. BESIII Data • World’s largest ψ(3770) sample • Tools/techniques for precision charm physics still under development – all results are PRELIMINARY • analysis is “partially blind” – 0.92 fb-1 analyzed so far. Full 2.9 fb-1 later for final results Ron Poling - ICHEP 2012

  8. - Tag Selection • Nine D- tag modes BESIII Preliminary Ron Poling - ICHEP 2012

  9. - Signal Selection BESIII Preliminary • Exactly one track in addition to tag, with the right charge • Positive muon identification • No extra photon • Select on consistency with leptonic decay: BESIII Preliminary 425 signal candidates: small BG, mom. dist. consistent with Ron Poling - ICHEP 2012

  10. - Sample Events • Positive muon ID requirement reduces background at the expense of a ~20% efficiency loss Ron Poling - ICHEP 2012

  11. - Backgrounds BESIII Preliminary MC MC BG est.: Indep. data est.: Ron Poling - ICHEP 2012

  12. - Results BESIII Preliminary • Excellent agreement with CLEO-c • Still statistics limited – need more data! Ron Poling - ICHEP 2012

  13. - Comparisons (from G. Rong) LQCD (HPQCD 2012) (208.3±1.0±3.3) MeV LQCD (FNAL/MILC 2012) (219±11) MeV Ron Poling - ICHEP 2012

  14. - Tag Selection • Four D0 tag modes Ron Poling - ICHEP 2012

  15. - Signal Selection BESIII Preliminary • Tag plus exactly two oppositely-charged tracks • Kaon/pion/electron ID • Electron has right charge • No extra neutral energy • Select on consistency with semileptonic decay BESIII Preliminary • Fit U distribution to extract yield Ron Poling - ICHEP 2012

  16. - Branching Fraction • Systematic uncertainties are preliminary • Good consistency with CLEO-c, statistical precision is comparable with only 1/3 data analyzed BESIII Preliminary Ron Poling - ICHEP 2012

  17. - q2distribution with • Partition D0semileptonic candidates in bins of • Fit U distribution in each q2 bin BESIII Preliminary BESIII Preliminary Ron Poling - ICHEP 2012

  18. - Project f(q2) • Points are data with statistical errors only • Curves are Fermilab/MILC (arXiv:1111.5471) with ±1σ (statististical) bands BESIII Preliminary BESIII Preliminary Ron Poling - ICHEP 2012

  19. - FF Parameterizations Simple Pole Model Modified Pole Model Becirevic and Kaidalov PLB 478, 417 (‘00) Series Expansion Becher and Hill PLB 633, 61 (‘06) Ron Poling - ICHEP 2012

  20. - FF Fits Ron Poling - ICHEP 2012

  21. - FF Results • Reasonable consistency with CLEO-c, comparable precision with 2/3 of data still to analyze BESIII Preliminary Ron Poling - ICHEP 2012

  22. Future Charm Prospects at BESIII • Finalize and on the 2.9 fb-1ψ(3770) sample • Extend to and other modes • Highlights of coming data runs: 2012-2013ECM=4260 and 4360 MeV for “XYZ” studies (0.5 fb-1 each) 2013-2014ECM=4170 MeV for Ds (~2.4 fb-1) TBD Additional ψ(3770) data Ron Poling - ICHEP 2012

  23. Summary and Conclusions • First results from the BESIII experiment have been presented on • D+Leptonic Decays • D0Semileptonic Decays • BESIII has arrived for precision charm physics, with more data and more measurements to come Ron Poling - ICHEP 2012

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