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Recent results on D meson decays from BES

Recent results on D meson decays from BES. Ma HaiLong [For BES Collaboration] Institute of High Energy Physics, Beijing China CHARM06 Beijing China 2006-6-5. Outline. Introduction. Singly tagged D samples. Semileptonic decays. Inclusive decays. Summary. BEPC collider.

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Recent results on D meson decays from BES

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  1. Recent results on D meson decays from BES Ma HaiLong [For BES Collaboration] Institute of High Energy Physics, Beijing China CHARM06 Beijing China 2006-6-5

  2. Outline • Introduction • Singly tagged D samples • Semileptonic decays • Inclusive decays • Summary

  3. BEPC collider L ~ 11031 /cm2s @3.773GeV Ecm~2-5 GeV

  4. BESII detector VC: xy = 100 m TOF: T = 180 ps  counter: r= 3 cm MDC: xy = 220 m BSC: E/E= 22 % z = 5.5 cm dE/dx= 8.5 %  = 7.9 mr B field: 0.4 T p/p=1.7%(1+p2) z = 3.1 cm

  5. dE/dx and TOF information μ identification can be done by the μ Counter for the charged track with momentum of greater than 0.55 GeV/c dE/dx TOF

  6. (3770) data sample ~18 pb-1 data taken at 3.773 GeV ~7 pb-1 data taken at the region from 3.768 GeV to 3.778 GeV ~8 pb-1 data taken in the energy region from 3.665 to 3.878 GeV The total Luminosity is about 33 pb-1

  7. Motivation Isospin conservation implies The called “Longstanding puzzle” in Charm decay! Is isospin conservation held in the D semileptonic decays? PDG04 BF The puzzle has beensolved! BESII [Phys. Lett. B608(2005)24] Branching fractions CLEO [Phys. Rev. Lett. 95(2005)181801] CKM matrix elements and form factors

  8. Motivation Early theories: 0.9-1.3 Measurements: Form factor E691 0.45±0.11 MARKIII 1.00±0.25(absolute) CLEO 0.51±0.18±0.06 CLEO 0.60±0.09±0.07 CLEO 0.65±0.09±0.10 E687 0.59±0.10±0.13 E687 0.62±0.07±0.09 CLEO 0.99±0.06±0.07±0.06 FOCUS 0.594±0.043±0.030 CLEO-c 0.63±0.03±0.02 Recent theories:0.5-0.7 Shift in form factor prediction of early theory MARKIII use a lower BF(D+→K0e+ve ) Branching fractions

  9. Motivation Up to now, PDG has not summarized the branching fractions for some inclusive decays of D mesons Measurements of branching fractions for the inclusive decays of D mesons serve as check on the sum of the branching fractions for the exclusive D decays provide information about the relative strength of Cabibbo-favored and Cabibbo-suppressed D decays.

  10. Singly tagged D samples Near DD-bar production threshold region Singly tagged D sample K+ K+ D D π– tag tag π– π– D- e+ e- e+ e- D D D+ Absolute Measurements X0 X+ • Semileptonic decays • Inclusive decays Throughout the talk, charge conjugation is implied

  11. Singly tagged D samples ND-Tag=5321±125±160 ND0Tag=7584±198±241 Mass[mKnπ] Singly tagged D- modes: (a)K+π-π-; (b) K0 π-;(c) K0 K-; (d) K+K-π-; (e) K0π-π-π+; (f) K+π-π-π0; (g) K0π-π0;(h) K+π-π-π-π+; (i) π-π-π+; (j) Sum Singly tagged D0 modes: (a)K+π-; (b) K+ π-π-π+; (c) K0 π-π+; (d)K+ π-π0

  12. Semileptonic decays Singly tagged D sample K+ D tag Should be around zero due to the mass of the missing neutrino is zero Umiss=Emiss-pmiss π– e+ e- D |Umiss|<2[3]σUmiss No surplus charged track and good photon on the recoiling side

  13. Candidates for Monte Carlo simulation |Umiss|<2σUmiss Umiss (GeV)

  14. Candidates for The yellow parts are from background events Candidates for Candidates for Mass[mKnπ]

  15. Preliminary Results An upper limit at 90% C.L is set to be <0.89% • Branching fractions • The ratio of BFs • Ratio of partial width

  16. Candidates for Monte Carlo simulation |Umiss|<3σUmiss Umiss (GeV)

  17. Candidates for Mass[mKnπ] Mass[Kπ]

  18. Results • Branching fractions(%) • Ratio of partial width Tend to support a smaller ratio Accepted by EPJC: hep-ex 0605103

  19. Candidates for No signal event is observed (%) (%) (%) 90%CL Results Accepted by EPJC: hep-ex 0604033

  20. Inclusive Decays Singly tagged D sample K+ D tag π– Measurements of branching fractions for the inclusive decays of D mesons e+ e- D X0

  21. Candidates for Cabibbo favored decay Cabibbo suppressed decay D0 signal region D0 signal region D0 sideband D0 sideband D- signal region D- signal region D- sideband D- sideband Mass[K-π+] Mass[K+π-]

  22. Results Cabibbo favored decay: Cabibbo suppressed decay: Phys. Lett. B625(2005)196

  23. Candidates for D0 signal region D- signal region D0 sideband D- sideband

  24. Candidates for Cabibbo favored decay Cabibbo suppressed decay D0 signal region D0 signal region D0 sideband D0 sideband D- signal region D- signal region D- sideband D- sideband

  25. Preliminary results 90%CL

  26. Summary BES measured branching fractions of D semileptonic decay • The ratio of • The ratio of • BES search for and BES measured branching fractions for inclusive decays Thank You！

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