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Recent Results From CLEO-c

Recent Results From CLEO-c. Les Rencontres de Physique de la Vallee D’Aoste February 27 – March 5, 2005. Alex Smith University of Minnesota. Motivation Leptonic D decays Semileptonic D decays Exclusive Inclusive D hadronic BR, s (DD) Conclusions.

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Recent Results From CLEO-c

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  1. Recent Results From CLEO-c Les Rencontres de Physique de la Vallee D’Aoste February 27 – March 5, 2005 Alex Smith University of Minnesota • Motivation • Leptonic D decays • Semileptonic D decays • Exclusive • Inclusive • D hadronic BR, s(DD) • Conclusions Alex Smith – University of Minnesota

  2. Ability to run at cms energies from J/y up to U(5S) y’ y(3770) CLEO-c Detector/CESR-c Accelerator CLEO III CLEO-III CLEO-c Mini Drift Chamber SVX SVX • Simple conversion of detector from U(4S) to y(3770) running • Addition of superconducting wigglers to CESR required for low energy running • Additional damping to compensate for lower synchrotron radiation Beam Energy (GeV) Alex Smith – University of Minnesota

  3. No extra energy for fragmentation particles Known/coherent initial state Clean neutrino reconstruction Simple combinatorics Large cross section Good kinematic particle ID Running at the y(3770) Ecm ~ U(4S) Ecm ~ y(3770) CLEO III CLEO-c Alex Smith – University of Minnesota

  4. Electroweak Physics e+ W+ Strong Physics Impact of CLEO-c Measurements • Calibration and validation of Lattice QCD • Test theoretical form factor calculations and models • Impacts prediction of form factors for B meson decays • Measurements of |Vcs| and |Vcd| • Improved decay constants fB possible from CLEO-c fD measurement + LQCD • Improved measurement of many important normalization modes Alex Smith – University of Minnesota

  5. l Vus/Vus =1% l Vud/Vud 0.1% Vub/Vub 15% e B n n K n n p p  Vcb/Vcb 5% Vcd/Vcd 7% Vcs/Vcs =16% l l D n B n l D K D n p Vtb/Vtb 29% Vtd/Vtd =36% Vts/Vts 39% W t b Bd Bd Bs Bs CLEO-c + Lattice QCD +B factories CLEO-c + Lattice QCD +B factories + ppbar CLEO-c The Future of Precision Flavor Physics The Goal: Measure all CKM matrix elements and associated phases in order to over-constrain the unitary triangles Alex Smith – University of Minnesota

  6. Many large BR tag modes ~25% Efficiency for reconstructing a tag Signal is very pure after tagging 28651 +/-207 tag cand. Tag D m+ Signal D n • Tag D decay modes: • Fit for (“missing mass”)2: D Leptonic Decays: D+m+n Getting the ABSOLUTE branching fractions... “Other side D” tag e+ e- • Additional charged track presumed to be m+ Alex Smith – University of Minnesota

  7. Monte Carlo (1 fb-1) Will also measure Ds+m+n in run above DsDs threshold D Leptonic Decays: D+m+n Data (60 pb-1) 8 candidate events 1 background event in signal region First Observation! Published in PRD Phys. Rev. D, 70, 112004 (2004) 4X statistics by end of April Alex Smith – University of Minnesota

  8. Reconstruct one D meson in hadronic tagging channel Reconstruct the remaining observable tracks Use the missing energy (Emiss) and missing momentum (|Pmiss|) in the event to form kinematic fit variable for the neutrino Signal component from fit to variable U From Monte Carlo/Data From fit of Mbc and DE for number of tags Both flavors combined: Exclusive Semileptonic D Meson Decays Technique: Alex Smith – University of Minnesota

  9. Exclusive Semileptonic D0 Meson Decays Cabibbo suppressed modes Cabibbo favored modes (~110 events) (~1400 events) Events / ( 10 MeV ) Events / ( 10 MeV ) U = Emiss– Pmiss(GeV) U = Emiss– Pmiss(GeV) (~30 events) Events / ( 10 MeV ) (~90 events) Events / ( 10 MeV ) U = Emiss– Pmiss(GeV) U = Emiss– Pmiss(GeV) First Observation! Preliminary Alex Smith – University of Minnesota

  10. Exclusive Semileptonic D+ Meson Decays Cabibbo suppressed modes: Cabibbo favored modes: (~60 events) (~500 events) Events / ( 10 MeV ) Events / ( 10 MeV ) U = Emiss– Pmiss(GeV) U = Emiss– Pmiss(GeV) (~30 events) (~400 events) Events / ( 10 MeV ) Events / ( 10 MeV ) U = Emiss– Pmiss(GeV) U = Emiss– Pmiss(GeV) Preliminary Alex Smith – University of Minnesota

  11. Exclusive Semileptonic D+ Meson Decays (8 events) Events / ( 10 MeV ) U = Emiss– Pmiss(GeV) First Observation! Preliminary Alex Smith – University of Minnesota

  12. Exclusive Semileptonic D0 Decays Now (60 pb-1): Preliminary CLEO-c goal: Alex Smith – University of Minnesota

  13. |Vcs| or |Vcd| e+ W+ c Assuming a precision of ~3% for the SL form factors and ~1% for the decay constants is achieved by the theory: • Error on |Vcd| of ~1.4% (presently 7%) from D+m+n and Dpen • Error on |Vcs| of ~1.1% (presently 16%) from Ds+m+n, Ds+t+n and DKln Extracting Decay Constants, FF, |Vcs| and |Vcd| Use ratio of semileptonic to leptonic branching ratios to eliminate CKM element and isolate hadronic terms: Theory is calibrated/tested with this data Alex Smith – University of Minnesota

  14. Tag opposite side D meson Identify electron Select correct e charge using opposite side D meson: Charge of K for D0 D meson charge for D+/- Correct for electron efficiency and backgrounds Efficiency from reweighted radiative Bhabhas Fake rates Inclusive Semileptonic D Meson Decays Technique: Alex Smith – University of Minnesota

  15. Preliminary CLEO-c (in D rest frame) Inclusive Semileptonic D Meson Decays Alex Smith – University of Minnesota

  16. Inclusive Semileptonic D Meson Decays tag mode tag mode Preliminary Results--- No BR yet Combining tag modes: Alex Smith – University of Minnesota

  17. Independent of integrated luminosity! D Hadronic BR’s and Production Cross Sections Single tagged Double tagged DX DXj e+ e- e+ e- DXi DXi Alex Smith – University of Minnesota

  18. D Hadronic BR’s and Production Cross Sections Fitting technique • A simultaneous fit for all BR and cross sections is performed • Charged and neutral modes fit simultaneously • All correlations taken into account • These systematic errors are included in the fit • Efficiencies • Denominator of efficiency may be determined using missing mass in data and MC (all particles measured) • Uncertainty on charged track efficiencies will go down by factor of four • Improvements to uncertainties on p0 and KS0 efficiencies nearing completion Alex Smith – University of Minnesota

  19. D Hadronic BR’s and Production Cross Sections Double Tag Yields Preliminary Key Variables for extracting yields: ~2500 Double Tagged D0 ~500 Double Tagged D+ Alex Smith – University of Minnesota

  20. D Hadronic BR’s and Production Cross Sections Single Tag Yields Preliminary Alex Smith – University of Minnesota

  21. D Hadronic BR’s and Production Cross Sections Preliminary Cross sections: Charged Modes: Stat. Errors ~ 4.5% Neutral Modes: Ratios: Stat. Errors ~ 2.0% Alex Smith – University of Minnesota

  22. D Hadronic BR’s and Production Cross Sections Results shown normalized to PDG values Preliminary • PDG global fit includes ratios to D0K-p+ and D+K- p+p+ • Charged and neutral modes are correlated in that fit • Our results higher than PDG • Final state radiation (FSR) included in our results and not in PDG results • 1-2% increase depending on mode Alex Smith – University of Minnesota

  23. D Hadronic BR’s and Production Cross Sections B(D0"K-p+) • Branching fractions and cross sections are competitive with world averages with only ~60 pb-1 • Results are presently systematics limited but improving • Dominant per track systematic error recently improved by factor of 4! • Most systematic errors will improve with luminosity, however • Four more D+ modes being added (3X DT statistics) • These measurements will impact the determination of |Vcb| (from BD*ln) (Bands are PDG average, NOT global fit) B(D+"K- p+p+) Preliminary Alex Smith – University of Minnesota

  24. CLEO-c Impact on the Unitarity Triangle Now: Theory uncertainties dominate With few % theory errors made possible by CLEO-c and 500 fb-1 each from the B factories: Alex Smith – University of Minnesota

  25. Other CLEO-c Physics Not Covered in This Talk • y(3770) • Data still coming in, luminosity improving • y’ • Large sample collected... lots of results • Observation of hc • Ecm ~ 4140 MeV (just above Ds pair threshold) • fDs from Ds+m+n • Ds semileptonic decays • J/y • Sample of 109 J/y’s anticipated • Radiative J/y decays • Glueball candidates, hybrids, ... Alex Smith – University of Minnesota

  26. Summary • CLEO-c is producing results that will have a broad impact on the field • These measurements are essential for other measurements at the B Factories and Tevatron to realize their full potential • With only 60 pb-1 of y(3770) data analyzed many measurements are already the best • Exciting results on the horizon • More data on y(3770) • Data at Ecm above 2MDs threshold • J/y radiative decays Alex Smith – University of Minnesota

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