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Charm Physics Results at BES and Prospects at BESIII BESIII is successor of the previous successful BES. Haibo Li On behalf of BES Collaboration Institute of High Energy Physics International Workshop e+e- Collisions from to y February 27 - March 2, 2006, Budker Institute of Nuclear Physics, Novosibirsk, Russia 2006-2-26 Haibo Li, IHEP, BES collaboration 1 Open Charm Production at BES Tag one D meson in a selected tag mode. Study decays of other D, (signal D) 22% tagging efficiency (<1% @ Y(4S) for B) Absolute Charm Branching fractions BESII had small sample of DD #D0D0bar #D+D- 9.6 pb-1 3.5104 2.8104 BESII 33 pb-1 0.12106 0.09106 CLEO-c(goal) 3 fb-1 10.8106 8.4106 BES III(goal) 20fb-1 72106 55106 Experiments e+e- machines Luminosity@ ECM=3770MeV Mark III Charm Mixing, DCS, and cosd impact naïve interpretation of branching fraction analysis extension of Phys.Lett.B508:37-43,2001 hep-ph/0103110 Gronau/Grossman/Rosner & hep-ph/0207165 Atwood/Petrov See Asner & Sun, hep-ph/0507238 2006-2-26 Haibo Li, IHEP, BES collaboration 2 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) Haibo Li, IHEP, z =BES 3.1collaboration cm 2006-2-26 3 D Signal Reconstruction ∆E In y(3770) rest frame: E ED - Ebeam 2 M ES Ebeam - pD2 D e- e+ Υ(4S) MES 2006-2-26 Haibo Li, IHEP, BES collaboration D 4 Single Tag D at BESII BESII 33 pb-1 0 Single Tag D D - K - - D K - D- KS0 K - 0 D K - - D- KS0 - D - K K - D- KS0 - - 0 0 S 0 - 0 D K D- KS0 - 0 - K - - 0 D K K - - Total 9 modes D- - - N 0 D tag 2006-2-26 7584 198 341 N D - 5321 149 160 tag Haibo Li, IHEP, BES collaboration 5 Exclusive Semileptonic BF Vcq W+ D Analysis Techniques e+ Fit to Umiss P, V 2 F d P G Vcq 2 dq 24 3 2 pP3 f p q 2 2 Decay rate for D P B Nsignal / signal Nsignal / Xe Ntag / tag Ntag Fit to MBC • Reconstruct one hadronic D tag. • Reconstruct a semileptonic signal candidate from the remaining tracks/showers. • Fit kinematic variable Umiss ( = Emiss – |Pmiss| ) for the missing neutrino of the signal. 2006-2-26 Latest LQCD, PRL 94, 011601 (2005) LQCD : shape & rate precision~10% Haibo Li, IHEP, correct: BES collaboration 6 Absolute Semileptonic Branching fractions at BESII Decay Modes BR (%) BESII (33 pb-1) BR (%) PDG BR( D0 K -e e ) 3.82 0.40 0.27 3.58 0.18 BESII 33 pb-1 BR(D0 K - ) 3.60 0.60 0.60 3.19 0.17 BR(D0 -e e ) 0.33 0.13 0.03 0.36 0.06 PLB 608 24 (2005) PLB 597 39 (2005) BR(D0 - ) 0.38 0.31 0.10 BR(D K e e ) 2.82 1.39 0.31 2.86 0.46 The Yellow region are preliminary results BR(D0 K 0 -e e ) 2.60 1.04 0.27 1.8 0.8 BR( D K 0e e ) 8.95 1.59 0.67 6.6 0.9 BR(D K 0 ) 10.3 2.30 0.80 7.0 0.25 BR(D K *0e e ) 4.89 1.19 0.36 4.5 0.6 BR(D K - e e ) 3.46 0.75 0.26 4.1 0.8 0 *- ( D 0 K - ) ( D K ) 0 For extractions of ratios of Vcd/Vcs and form factors Br ( D 0 - ) Br ( D 0 K - ) 2006-2-26 : 0.11 0.10 0.03 ( D 0 K - e ) ( D K 0 e ) ( D 0 K - e ) Isospin test – Puzzle in PDG 1.4 0.2 = 0.89 0.24 0.15 1.00 0.05( stat ) 0.04( sys) CLEO-c 1.08 0.22( stat ) 0.07( sys) BES-II ( D K 0 e ) Haibo Li, IHEP, BES collaboration 7 Ratio of the D->K*e and D->Ke test of HQET BESII 33pb-1 Preliminary: ( D 0 K * - e e ) 0.74 0.37 0.04 0 - ( D K e e ) ( D K *0 e e ) 0.55 0.17 0.02 0 ( D K e e ) World average: ( D K *l l ) 0.56 0.05 ( D Kl l ) LQCD, Quark model predict: 0.9 – 1.2 by Wirbel 1985, Isgur 1989 ,Bernad 1991 New prediction: ISGW2 model with a small axial form factor give a small BR(K*e) : 0.54 2006-2-26 Haibo Li, IHEP, BES collaboration 8 Search for D+ l+v, + at BESII 33pb-1, BESII preliminary submitted to EPJc BR( D e e ) 2.01% @ 90%, D+ + BR( D ) 2.04% @ 90%, BR( D ) 0.062 0.012 0.003, BR( D K - ) BR( D ) (5.7 1.1 0.5) 10-3 , m(K+K-) D+K-- Tagged D mass 2006-2-26 Haibo Li, IHEP, BES collaboration 9 fD+from Absolute Br(D+ at BESII BESII Tag D fully reconstructed PLB610,183(2005) p A from another D , Compute missing mass2: peaks at 0 for signal S=3 B=0.33 MM 2 ( Ebeam - E )2 - (- PDtag - P )2 .1 -4 BR( D ) (12.2 -11 1 . 0 ) 10 , 5.3 129 f D (371-119 25) MeV BESII -4 BR( D ) (4.40 0.66-00..09 ) 10 , 12 f D (222.6 16.7 -32..48 ) MeV 2006-2-26 Haibo Li, IHEP, BES collaboration CLEO-c PRL,95 251801(2005 ) 10 Measurements of the Cross Sections@3770MeV •Unique event properties BESII 33 pb –1, double tag –Only DD not DDx produced –Can get DoDo, D+D-, DsDs Nucl. Phys. B 727395(2005): 0 (e e - D 0 D ) obs (3.47 0.32 0.21)nb (e e - D D - ) obs (2.46 0.33 0.20)nb CLEO-c 56pb-1 : DT, PRL 95, 121801(2005): BESII single Tag: PLB 603(2004)130 0 ( D 0 D 0 ) (3.60 0.07-00..07 05 ) nb 10 ( D D - ) (2.79 0.07-00..04 )nb (e e - D 0 D ) obs (3.58 0.09 0.31)nb (e e - D D - ) obs (2.56 0.08 0.26)nb The double tag results are dominated by statistic error ! (+-)= 5.4 nb at 4 GeV 2006-2-26 +-)) Haibo Li, IHEP,of BES( collaboration R (units 11 Rare decays from BESII 33pb-1 at BESII BESII: 33pb-1 mode Signal Efficiency Upper limits PDG (2004 K0 e+e- 0 2.64% 5.710-4 1.110-4 e+e- 0 0.64% 2.410-3 5.210-5 re+e- 0 4.32% 3.510-4 1.010-4 K*0 e+e- 1 2.06% 1.310-3 4.710-5 K-e+e 0 9.64% 2.510-4 1.210-4 K+e+e- 0 9.20% 2.610-4 2.010-4 -e+e 0 10.20% 2.410-4 9.610-5 e+e- 1 10.49% 4.110-4 5.210-5 K*-e+e 0 0.40% 6.210-3 N/A K*+e+e- 0 0.39% 6.310-3 N/A The signal region is clean! experimentally, it is easy. 2006-2-26 LFV processes Haibo Li, IHEP, BES collaboration 12 Single D production in huge J/y Decays at BESII mDs mDmD0 Background level is small! 58 millions J/y at BESII J/y weak decays J / Ds- e e , ( Ds , K - K *0 ) J / D - e e , ( D - K - ) J / D 0 e e - , ( D 0 K - , K 2 , K 3 ) J / Ds- e e 4.6 10-5 J / D - e e 1.110-5 J / D 0 e e - 9.2 10-6 BESII preliminary results First look in J/y in the world! 2006-2-26 Haibo Li, IHEP, BES collaboration 13 BESIII Detector Two rings, 93 bunches: • Luminosity 1033 cm-2 s-1 @1.89GeV 6 1032 cm-2 s-1 @1.55GeV Magnet: 1 T Super conducting 6 1032 cm-2 s-1 @ 2.1GeV MDC: small cell & He gas xy=130 m sp/p = 0.5% @1GeV dE/dx=6% TOF: T = 100 ps Barrel 110 ps Endcap Muon ID: 9 layer RPC EMCAL: CsI crystal E/E = 2.5% @1 GeV z = 0.6 cm/E Data Acquisition: Event rate = 3 kHz Thruput ~ 50 MB/s Trigger: Tracks & Showers Pipelined; Latency = 6.4 s The detector is hermetic for neutral and charged particle with excellent resolution ,PID, and large coverage. 2006-2-26 Haibo Li, IHEP, BES collaboration 14 Charm Productions at BEPCII Average Lum: L = 0.5×Peak Lum.; One year data taking time: T = 107s Nevent/year = exp L T Resonance Mass(GeV) CMS Peak Lum. (1033cm-2s-1) Physics Cross Section (nb) Nevents/yr J/y 3.097 0.6 3400 10 109 t 3.670 1.0 2.4 12 106 y(2S) 3.686 1.0 640 3.2 109 D0D0bar 3.770 1.0 3.6 18 106 D+D- 3.770 1.0 2.8 14 106 DsDs 4.030 0.6 0.32 1.0 106 DsDs 4.140 0.6 0.67 2.0 106 Huge J/y and y(2S) sample at BESIII; Note: in this talk, all R&D study are based on 4 years’ Lum. for D and Ds ( 20 fb-1) and one year’s Lum. for J/y (10 billion) and y(2S) (3.0 billion). 2006-2-26 Haibo Li, IHEP, BES collaboration 15 Absolute Charm Branching fractions at threshold at BESIII (MBC) ~ 1.2-1.3 MeV, x2 with 0 (E) ~ 7—10 MeV, x2 with 0 Single tags Double tags K K vs K K D0->K-π+ Monte Carlo Single tags D+->K-π+π+ Monte Carlo Independent of L and cross Section in a double tags measurements # (K - - ) Observed in tagged events B( D K ) detection efficiency for (K - - ) #D tags - Monte Carlo 2006-2-26 - - Haibo Li, IHEP, BES collaboration 16 Semileptonic decay and CKM Matrix at BESIII d D P dq 2 Δ Vcq Vcq 2 Vcq PP3 24 f (q ) 2 2 To find Vcs & Vcd need form factor from theory at one fixed q2 point. Δτ ΔB ΔFF D 2τ 2FF 2B D 2 3 2 2 dVcd/Vcd dVcd/Vcd1.7% 4% D D Δτ Ds Δτ D 0.6% τD Form factor term come from theory (Lattice QCD). Supposing ΔFF/FF ~3% , BESIII will get BESIII: Integrate Lumi. 20fb-1 DDbar MC simulation f (q 2 ) ll 1.0% Well measured dVcs/Vcs dVcs/Vcs1.6% 11% DD τ Ds f (0) 2 1 - q 2 / mpole l l K Great contribution to CKM Unitarity K Quark models, HQET, Lattice & other methods have all been invoked to calculate form factor absolute normalizations. These calculations have been done mostly at q2 =0 orBESIII q2 =q2max. (i..e w=1, just like F in Vcb in B D* l) 2006-2-26 Haibo Li, IHEP, BES collaboration 17 Precision of fD(s) at BESIII f D(s) 3 generation unitarity global fit: f D(s) hep-ph/0406184 CKMfitter group Δ | Vcd | 1.1% | Vcd | Δτ D 0.6% τD With 20fb-1 at BESIII Δ | Vcs | 0.06% | Vcs | Δτ Ds 1.0% τ Ds ΔB 2% B 1 t D(s) 2 tD (s) 2 1 B 2 | Vcd(s) | 2 B | Vcd(s) | Δf D 1.5% BESIII fD Δf Ds 1.1% BESIII f Ds Challenge LQCD Prediction! BESIII MC with 1 million Ds 2006-2-26 Haibo Li, IHEP, BES collaboration 18 2 input to 3 /γ: B- DK-, D Ks limited by uncertainty due to Dalitz plot model currently 10-110 – Extract strong phase and study CP violation by using CP tag. – Study light scalar in Dalitz D decays , k S-waves in D+ , K CLEO II.V - D0KS+K*(892)- m2(-) (GeV2) – D Dalitz Plot method CP+ f0(980) As Alex Bondar pointed out, CP tagged DKS can be 10K in 10fb-1 y(3770) sample at BESIII, it will give a uncertainty below 20on 3 /γ! But note that the D0KS is dominated by r and K* which are longitudinally polarized. The most interesting events are accumulated near the corner of the Dalitz, which have very soft Ks or pion, this effect may affect the real efficiency on the CP- r(770) DP, especially, have very low efficiency near the kinematic limit of DP. We have to do MC simulation m2(KS)RS (GeV2) to test it at BESIII?? A. Bondar et. al hep-ph/0510246 2006-2-26 Haibo Li, IHEP, BES collaboration 19 Measurement of Strong Phase I. Shipsey Flavor mode rD = 3.3 10-3 –cos dD ~ 10% cos dD ~ 2% at BESIII rD 2006-2-26 Haibo Li, IHEP, BES collaboration 20 Relative yield of charged and neutral D pairs at y(3770) the resonance region (1) From CLEO-c L = 55.8 pb-1 @ 3770 MeV: f (e e - D D - ) (e e - D 0 D 0 ) 014 0.776 0.024-00..006 Can phase space difference explain all the effect? If only phase space f = 0.69, which can not explain data! e+ 3 f p 0.69 p00 Phys.Rev.Lett. 90, 142001 (2003)R. Kaiser et al. y(3770) e- g* Coulomb correction y(3770) 3 * f FC p , FC (1 ) p00 2 Yukawa correction Two additional source sources: (1) Coulomb interaction between charged meson 1%—5% M. Voloshin hep-ph/0402171 (2) Possible continuum contribution (EM process) Both above are EM process which may violate the isospin symmetry or violate the single iso-vector dominate. 2006-2-26 Haibo Li, IHEP, BES collaboration 21 Relative yield of charged and neutral D pairs at y(3770) the resonance region (2) According to M. Voloshin model (hep-ph/0402171), one can get: (e e - D D - ) p f ( ECM ) FC p00 (e e - D 0 D 0 ) FC 1 p p00 3 ( ECM , a, d ) 3 ECM is the central mass of energy; a is the distance parameters ; d = dBW + d1 Coulomb interaction between charged mesons d1 is the phase for non-resonant scattering, and dBW is the y(3770) BW phase . Phase space difference It will be interesting to look at the ratio f vs ECM. A finer scan of the ratio of the cross sections will be very useful to test the prominent variation (1%-5%)in the vicinity of y(3770) peak at BESIII 2006-2-26 f Haibo Li, IHEP, BES collaboration hep-ph/0402171 hep-ph/0602233 M. Voloshin ECM 22 D Mixing D 0shifts energy of CP eigenstates D0 D 0 - y 2 0 Dshifts lifetimes of 2M 12 y 12 x CP eigenstates x mixing: Channel for New Physics. y (long-range) mixing: SM background. New physics will enhance x by entering the loop but not y. Rmix 2006-2-26 1 2 x 2 y Haibo Li, IHEP, BES collaboration 2 23 BES III Charm Mixing Mixing: y(3770)DD(C = -1) Coherence simplifies study DCSD interfere away so not a background Unmixed: D0 K-+ D0 K+mixing: D0 K-+ D0 D0 K-+ Can add lepton final states (Klv Klv) Sensitivity: current limit: 10-3 2 ( D 0 D 0 ( K - )(K - )) x 2 y 2 p B 2 K - 2 2 ( D 0 D 0 ( K - )(K - )) 2 q B K rMixing at BESIII K- vs K- in (K-)(K-) ~1 background event is expected rD sensitivity is abut 1x10-4 @90% C.L. K- vs KBESIII Monte Carlo Simulation 2006-2-26 Haibo Li, IHEP, BES collaboration Efficiency: 12.5% 24 Direct CP Violation at ψ(3770) at BESIII K K- Acp D 0 D Im VcdVud* VcsVus* 2 sin d PT P T A2 4 sin d PT •CP violating asymmetries can be measured by searching for events with two CP odd or two CP even final states ex: 0 π π - P 10-3 T -, KK-, 0 0, Ks0 , for the decay of ψ f1 f 2 CP( f1 f 2 ) CP( f1 ) CP( f 2 ) (-1) L CP(ψ) ACP sensitivity is about 10-3 @90% C.L. K K vs It is also true in phi decay: hep-ph/0511222 BESIII MC simulation Rss Beam constraint Mass =(10.70.8)10-6 2006-2-26 Haibo Li, IHEP, BES collaboration BR(KSKS)= (3.60.3)10-6 be accessible at KLOE? 25 Rare & Forbidden D Decays: FCNC, LFV, LNV Observation of D+ FCNC and lepton number violating decays could indicate new Focus hep-ex/0306049 and G. Burdman PRD66 014009(2002) Sensitivities 10-6 3fb-1 physics. Great improvement at BESIII with 20 fb-1, about 100 million DD pairs, but not competitive with 550 million DD pairs at B factory for rare decays The sensitivity will be 10-7 at BESIII CLEO-c hep-ex/0601007 D. Miller 281pb-1 D+ V + (V e+e- ) are main backgrounds, , r, 2006-2-26 Haibo Li, IHEP, BES collaboration 26 Access to Semileptonic Weak Decay of J/y (1) •Semileptonic decays: based on heavy quark spin symmetry: Br (J/y Ds l ) = 0.26 10 -8 A model independent prediction for the ratio of the above BRs: y DS*+ l R = ------------ 1.5 y DS+ l R= ; Z.Phys.C62:271-280,1994 M. Sanchis-Lozano More input from theorists ! Br (J/y Ds* l ) = 0.42 10 -8 Sun S.S et al at BESII are working on the above modes - -5 Based on 58 M J/y: Br( J /y DS e e ) 4.6 10 , Br( J /y D - e e ) 1.110-5 The rate of weak decay of J/y is at 10-8 level, and inclusive search at BESIII may be available: J/ y D*+S X y D*+ l D*+S DS+ g (soft g ) ------------ 1.5 + D + S y D l *0K K The sensitivity at BESIII: 10-7 – 10-8 KSK+ Detail simulations are being done at BESIII. ……. 2006-2-26 Haibo Li, IHEP, BES collaboration 27 Access to Weak J/y Decay at BESIII (2) •J/ y DS (DS*) M (M = , r, ,,’,K, K*,) J/ y PP hep-ph/9801202, K. Sharma We need more theoretical input! J/ y PV Mode Decay Br(10-10) ( 40% ) Mode Decay Br(10-10) ( 40% ) C = S=+1 (c s ) y DS+ y D0 K0 8.74 2.80 C = S=+1 (c s) y DS+ ry D0 K*0 36.30 10.27 C=+1,S=0 (c d) y DS+Ky D+y D0 y D0 ’ y D00 0.55 0.55 0.016 0.003 0.055 C=+1,S=0 (c d) yDS+K*y D+ry D0r0 y D0 y D0 2.12 2.20 0.22 0.18 0.65 y DS*+ - R = ------------ 3.5 y DS+ - 2006-2-26 < They are too rare to be searched at BESIII (1010) according to SM estimation. But sensitive to new physics if larger BRs measured. Haibo Li, IHEP, BES collaboration 28 Summary for BESIII Analysis review of BESIII • Charm Physics at threshold at BESIII • Absolute BRs, test of QCD • Charm event produced at threshold are very • Decay constants with double tags events clean with low multiplicity; fD+ : 1.5%; fDs : 1.1% with 20 fb-1 data • Charm events at threshold are pure DD pairs; • Form factors and Vcs and Vcd • D mixing at threshold Rmixing : 2.5 10-4 • Double tag studies are pristine; • Direct CP violations: ACP : 10-2 • Signal/Background is optimum at threshold; • The sensitivity of rare charm decay 10-7, at B factories : 10-7 500 fb-1 data • Neutrino reconstruction is clean; • Measurement of Strong Phase cos dD ~ 2% • Quantum coherence BESIII will provide unique opportunity for open charm physics: This comes at a fortuitous time, recent breakthroughs in precision lattice QCD need detailed data to test against. Charm is provide that data. If the lattice passes the charm test it can be used with increased confidence by: BABAR/Belle/CDF/D0//LHC-b/ATLAS/CMS/BTeV to achieve precision determinations of the CKM matrix elements Vub, Vcb, Vts, and Vtd thereby maximizing the sensitivity of heavy quark flavor physics to physics beyond the Standard Model. The start of data taking at BESIII promises an era of precise charm physics. 2006-2-26 Haibo Li, IHEP, BES collaboration 29 Thank you Спасибо 2006-2-26 Haibo Li, IHEP, BES collaboration 30 Back-up slides 2006-2-26 Haibo Li, IHEP, BES collaboration 31 Scan of the resonance region @ 3.7 4.6 GeV Test isospin symmetry far away from open charm threshold! Since the EM effect may be significant far away from DD threshold! f ( Ecm ) (e e - D D - (*) ) (e e D D - 0 0 (*) , ) Could possible EM contribution affect the ratio? 2 * * * Interference effect: A(e e g DD ) A(e e cc DD ) It will be very helpful to make a fine scan of the ratio @ 3.7 4.6GeV, so that one can understand the formation of DD system near or above the threshold 2006-2-26 Haibo Li, IHEP, BES collaboration 32 Scan of the resonance region @ 3.7 4.6 GeV(2) (*) (e e D D ), (e e - DS DS-(*) ), - (e e - J /y - ), (e e - cJ r ( )) Test QCD @ 3.7 4.6 GeV Search for exotic ccbar, Y(4260) (e e - ), (e e - J /y ) (e e - KK ), (e e - ) 2006-2-26 Probe gluon enhanced hidden ccbar states Haibo Li, IHEP, BES collaboration 33 D meson Decay Constants c Targeted near threshold at BES | Vcd(s) |2 f D2(s) W d s Decay is forbidden as ml0 : Helicity suppression l 2 m ( Dq ) 81 GF2 M D m2 (1 - 2 ) f D2 | Vcq |2 q M D (D e e ) : (D ) : (D t t ) 2.310 :1: 2.67 -5 (Ds e e ) : (Ds ) : (Ds t t ) 10-5 :1:10 f D(s) 1 t D(s) 2 tD (s) 2006-2-26 2 1 B 2 | Vcd(s) | 2 B | Vcd(s) | 2 (Ds (B ) |Vcs |2 (0.97) 2 ) |Vub |2 (0.003)2 J 0 The uncertainty of Decay constants: f D(s) ) |Vcd |2 (0.22) 2 (D Haibo Li, IHEP, BES collaboration M J 0 M 34 Challenge LQCD Prediction (I. Shipsey) Expt/LQCD consistent at 45% CL Now: LQCD error ~8% CLEO-c error 8% CLEO <5% within a year Need latest LQCD predictions to few % by summer 2006 f D+ & 2007 f Ds with 3fb -1 : f D to 2.3% f Ds to 1.9% @ s ~ 4140 MeV 2006-2-26 Haibo Li, IHEP, BES collaboration 35 Charm As a Probe of Physics Beyond the Standard Model CP asymmetry≤10-3 Rare decays ≤10-6 D0 - D0 mixing ≤10-2 G. Burdman and I. Shipesy hep-ph/0310076 High statistics instead of High Energy 2006-2-26 Haibo Li, IHEP, BES collaboration 36 In charm very difficult to calculate the SM rate for rare decays reliably. one of the most reliable: I. Shipsey R parity violating SUSY In the SM Burdman Short distance SM Penguin, W box B (D+ +e+e-) ~ 2 x 10-6 R-parity violating SUSY: B (D+ +e+e-) ~ 2.4 x 10-6 Short + long distance SM rho and phi e+e- Increase in rate is small but significant at low dilepton mass Current experimental limit CLEO II: B (D+ +e+e-) ~ 4.5 x 10-5 @ 90%CL Goal observe, and one day study dilepton mass 2006-2-26 Haibo Li, IHEP, BES collaboration 37 0 Preliminary results of BRs of y ( 3770 ) D D , D D , D D and y (3770) non- D D 0 . BES measured the branching fractions for inclusive non-DD-bar decays of y(3770) using two different data sample and two different methods Determined BF (y (3770) D0 D 0 ) (50.1 1.3 3.9)% from analysis BF (y (3770) D D- ) (35.9 1.1 3.5)% of R values BF (y (3770) DD ) (86.0 1.7 6.0)% BF (y (3770) non - DD ) (14.0 1.7 6.0)% and DD-bar cross sections These are first measurements by using 33pb-1 @BESII BF (y (3770) D D ) (46.8 5.2 3.2)% BF (y (3770) D D- ) (37.0 4.1 3.5)% BF (y (3770) DD ) (83.8 6.8 6.4)% BF (y (3770) non - DD ) (16.2 6.8 6.4)% BF (y (3770) non - DD ) 30.1% @ at 90%C.L. 0 2006-2-26 0 Haibo Li, IHEP, BES collaboration Obtained from fitting to the inclusive hadron and the DD-bar production cross sections simultaneously. 38 Compare B factories & Charm Factories (BB) tag Ldt=500fb-1 #B tags @B Factory ~1 -1 #D tags @Charm Factory (DD) tag Ldt=3fb CFactory 3 fb-1 Statistics limited 30 BFactory 500 fb-1 COMPARISON PDG04 Systematics & Background limited Br ( DS ) 25 fD fDs % Error Error (%) 20 15 10 Br (D K ) Br (D0 K) 5 0 2006-2-26 Haibo Li, IHEP, BES collaboration 39