Recent results on D meson decays from BES Ma HaiLong [For BES Collaboration] Institute of High Energy Physics, Beijing China CHARM06 Beijing China
Outline Introduction Semileptonic decays Summary Inclusive decays Singly tagged D samples
BEPC collider L ~ 1 /cm 2 E cm ~2-5 GeV
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
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
(3770) data sample ~18 pb -1 data taken at GeV ~7 pb -1 data taken at the region from GeV to GeV ~8 pb -1 data taken in the energy region from to GeV The total Luminosity is about 33 pb -1
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
Form factor E ±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 E ±0.10±0.13 E ±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: Measurements: Recent theories: MARKIII use a lower BF(D + →K 0 e + v e ) Shift in form factor prediction of early theory Branching fractions Motivation
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
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
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 ]
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
U miss (GeV) Monte Carlo simulation |Umiss|<2σ Umiss Candidates for
The yellow parts are from background events Mass[mKnπ]
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
Umiss (GeV) |Umiss|<3σ Umiss Monte Carlo simulation Candidates for
Mass[mKn π ]Mass[K π ]
Results Tend to support a smaller ratio Branching fractions(%) Ratio of partial width Accepted by EPJC: hep-ex
No signal event is observed 90%CL Accepted by EPJC: hep-ex Candidates for Results (%)
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+
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
Results Cabibbo favored decay: Cabibbo suppressed decay: Phys. Lett. B625(2005)196
Candidates for D 0 signal region D 0 sideband D - signal region D - sideband
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
Preliminary results 90%CL
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 !