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  Semileptonic decays  Summary  Inclusive decays  Singly tagged D samples

3. BEPC collider L ~ 1  10 31 /cm 2  s @3.773GeV E cm ~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+p 2 )  z = 3.1 cm

5. 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 dE/dx and TOF information

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

8. 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 Early theories: 0.9-1.3 Measurements: Recent theories:0.5-0.7 MARKIII use a lower BF(D + →K 0 e + v e ) Shift in form factor prediction of early theory Branching fractions Motivation

9. 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. 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 Motivation

10. Near DD-bar production threshold region π–π– e+e+ e-e- D D K+K+ π–π– tag D+D+ D-D- π–π– e-e- e+e+ D D K+K+ Singly tagged D sample Absolute Measurements  Semileptonic decays  Inclusive decays X+X+ X0X0 Throughout the talk, charge conjugation is implied Singly tagged D samples

11. Singly tagged D - modes: (a)K + π - π - ; (b) K 0 π - ; (c) K 0 K - ; (d) K + K - π - ; (e) K 0 π - π - π + ; (f) K + π - π - π 0 ; (g) K 0 π - π 0 ;(h) K + π - π - π - π + ; (i) π - π - π + ; (j) Sum Singly tagged D 0 modes: (a)K + π - ; (b) K + π - π - π + ; (c) K 0 π - π + ; (d) K + π - π 0 N D - Tag =5321±125±160N D 0 Tag =7584±198±241 Singly tagged D samples Mass[mKn π ]

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

13. U miss (GeV) Monte Carlo simulation |Umiss|<2σ Umiss Candidates for

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

15. Branching fractions Experiment BES MARKIII E687(93) E687(95) PDG04 Preliminary Results An upper limit at 90% C.L is set to be <0.89% The ratio of BFs Ratio of partial width

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

17. Mass[mKn π ]Mass[K π ]

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

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

20. Inclusive Decays Measurements of branching fractions for the inclusive decays of D mesons π–π– e-e- D D K+K+ tag Singly tagged D sample X0X0 e+e+

21. D 0 signal region Cabibbo favored decay Cabibbo suppressed decay Mass[K - π + ] Mass[K + π - ] D 0 sideband D - signal region D - sideband D - signal region D - sideband D 0 signal region D 0 sideband Candidates for

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

23. Candidates for D 0 signal region D 0 sideband D - signal region D - sideband

24. Candidates for Cabibbo favored decay Cabibbo suppressed decay D 0 signal region D 0 sideband D - signal region D - sideband D - signal region D - sideband D 0 signal region D 0 sideband

25. Preliminary results 90%CL

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