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Charm Physics Results at BES and Prospects at BESIII

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,

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Charm Physics Results at BES and Prospects at BESIII

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  1. 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 Haibo Li, IHEP, BES collaboration

  2. 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 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 Haibo Li, IHEP, BES collaboration

  3. BESII Detector VC:xy = 100 m TOF:T = 180 pscounter:r= 3 cm MDC: xy = 220 mBSC:E/E= 22 %z = 5.5 cm dE/dx= 8.5 % = 7.9 mrB field: 0.4 T p/p=1.7%(1+p2) z = 3.1 cm Haibo Li, IHEP, BES collaboration

  4. e- e- e+ e+ Υ(4S) D D D Signal Reconstruction Iny(3770)rest frame: ∆E MES Haibo Li, IHEP, BES collaboration

  5. Single Tag D at BESII Single Tag D BESII 33 pb-1 Total 9 modes Haibo Li, IHEP, BES collaboration

  6. e+ W+ Exclusive Semileptonic BF Vcq Analysis Techniques Fit to Umiss D P, V 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. Decay rate for D  P Latest LQCD, PRL 94, 011601 (2005) LQCD : shape & rate correct: precision~10% Haibo Li, IHEP, BES collaboration

  7. Absolute Semileptonic Branching fractions at BESII BESII 33 pb-1 PLB 608 24 (2005) PLB 597 39 (2005) The Yellow region are preliminary results Isospin test – Puzzle in PDG 1.4  0.2 = For extractions of ratios of Vcd/Vcs and form factors : Haibo Li, IHEP, BES collaboration

  8. Ratio of the D->K*en and D->Ken test of HQET BESII 33pb-1 Preliminary: World average: 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*en) :  0.54 Haibo Li, IHEP, BES collaboration

  9. Search for D+ l+v, p+ at BESII 33pb-1, BESII preliminary submitted to EPJc D+ p+ D+K-p+p- m(K+K-) Tagged D mass Haibo Li, IHEP, BES collaboration

  10. fD+from Absolute Br(D+  m+n) at BESII BESII PLB610,183(2005) Tag D fully reconstructed A  from another D , Compute missing mass2: peaks at 0 for signal S=3 B=0.33 BESII CLEO-c PRL,95 251801(2005 ) Haibo Li, IHEP, BES collaboration

  11. Measurements of the Cross Sections@3770MeV BESII 33 pb–1, double tag Nucl. Phys. B 727395(2005): • Unique event properties • Only DD not DDx produced • Can get DoDo, D+D-, DsDs BESII single Tag: PLB 603(2004)130 CLEO-c 56pb-1 : DT, PRL 95, 121801(2005): The double tag results are dominated by statistic error ! s(m+m-)= 5.4 nb at 4 GeV R (units ofs(m+m-)) Haibo Li, IHEP, BES collaboration

  12. Rare decays from BESII 33pb-1 at BESII BESII: 33pb-1 LFV processes The signal region is clean! experimentally, it is easy. Haibo Li, IHEP, BES collaboration

  13. Single D production in huge J/y Decays at BESII mDs J/y weak decays 58 millions J/y at BESII mD- mD0 Background level is small! BESII preliminary results First look in J/y in the world! Haibo Li, IHEP, BES collaboration

  14. BESIII Detector • Two rings, 93 bunches: • Luminosity • 1033 cm-2 s-1@1.89GeV • 6 1032 cm-2 s-1@1.55GeV • 6 1032 cm-2 s-1@ 2.1GeV Magnet: 1 T Super conducting 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 Data Acquisition: Event rate = 3 kHz Thruput ~ 50 MB/s EMCAL: CsI crystal E/E = 2.5% @1 GeV z = 0.6 cm/E Trigger: Tracks & Showers Pipelined; Latency = 6.4 ms The detector is hermetic for neutral and charged particle with excellent resolution ,PID, and large coverage. Haibo Li, IHEP, BES collaboration

  15. Charm Productions at BEPCII Average Lum: L = 0.5×Peak Lum.; One year data taking time: T = 107s Nevent/year = exp L T Huge J/ and (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/ (10 billion) and (2S) (3.0 billion). Haibo Li, IHEP, BES collaboration

  16. Absolute Charm Branching fractions at threshold at BESIII • s(MBC) ~ 1.2-1.3 MeV, x2 with p0 • s(DE) ~ 7—10 MeV, x2 with p0 Single tags Double tags K K vs K K D0->K-π+ Monte Carlo Monte Carlo BES III MC Single tags Independent of L and cross Section in a double tags measurements D+->K-π+π+ Monte Carlo Haibo Li, IHEP, BES collaboration

  17. Vcd/Vcd 1.7% Vcs/Vcs 1.6% l l l D n D n D n l K p K D n p BESIII Semileptonic decay and CKM Matrix at BESIII To find Vcs & Vcdneed form factor from theory at one fixed q2 point. Well measured Form factor term come from theory (Lattice QCD). Supposing ΔFF/FF ~3% , BESIII will get BESIII: Integrate Lumi.20fb-1DDbar MC simulation Vcd/Vcd 4% Vcs/Vcs 11% Great contribution to CKM Unitarity 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 or q2 =q2max. (i..e w=1, just like F in Vcb in B D* l) Haibo Li, IHEP, BES collaboration

  18. Precision of fD(s) at BESIII 3 generation unitarity global fit: hep-ph/0406184 CKMfitter group With 20fb-1 at BESIII Challenge LQCD Prediction! BESIII MC with 1 million Ds Haibo Li, IHEP, BES collaboration

  19. input to 3 /γ: • B- DK-, D Ks p+p- • 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 • s, k S-waves in D+ ppp, Kpp D Dalitz Plot method CLEO II.V - D0KSp+p- K*(892)- CP+ f0(980) m2(p-p+) (GeV2) As Alex Bondar pointed out, CP tagged DKSpp can be 10K in 10fb-1y(3770) sample at BESIII, it will give a uncertainty below 20on 3 /γ! But note that the D0KSpp 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 DP, especially, have very low efficiency near the kinematic limit of DP. We have to do MC simulation to test it at BESIII?? CP- r(770) m2(KSp)RS (GeV2) A. Bondar et. al hep-ph/0510246 Haibo Li, IHEP, BES collaboration

  20. Measurement of Strong Phase I. Shipsey Flavor mode rD = 3.3 10-3 • cos dD ~ 10% cos dD ~ 2% at BESIII Haibo Li, IHEP, BES collaboration

  21. Relative yield of charged and neutral D pairs at (3770) the resonance region (1) From CLEO-c L = 55.8 pb-1 @ 3770 MeV: Can phase space difference explain all the effect? If only phase space f = 0.69, which can not explain data! Phys.Rev.Lett. 90, 142001 (2003)R. Kaiser et al. e+ (3770) (3770) g* p* e- Yukawa correction Coulomb 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. Haibo Li, IHEP, BES collaboration

  22. Relative yield of charged and neutral D pairs at (3770) the resonance region (2) According to M. Voloshin model (hep-ph/0402171), one can get: ECM is the central mass of energy; a is the distance parameters ; d = dBW + d1 d1is the phase for non-resonant scattering, and dBW is the y(3770) BW phase . Coulomb interaction between charged mesons 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(3770) peak at BESIII f hep-ph/0402171 hep-ph/0602233 M. Voloshin ECM Haibo Li, IHEP, BES collaboration

  23. shifts energy of CP eigenstates shifts lifetimes of CP eigenstates D Mixing x mixing: Channel for New Physics. y (long-range) mixing: SM background. New physics will enhance x by entering the loop but not y. Haibo Li, IHEP, BES collaboration

  24. Mixing:y(3770)DD(C = -1) Coherence simplifies study DCSD interfere away so not a background Unmixed: D0 K-p+D0 K+p- mixing: D0 K-p+ D0 D0K-p+ Can add lepton final states (Klv Klv) Sensitivity: current limit: 10-3 BES III Charm Mixing K-p+ vs K-p+ in (K-p+)(K+p-) rMixing at BESIII ~1 background event is expected rD sensitivity is abut 1x10-4 @90% C.L. K-p+ vs K+p- BESIII Monte Carlo Simulation Efficiency: 12.5% Haibo Li, IHEP, BES collaboration

  25. Direct CP Violation at ψ(3770) at BESIII • CP violating asymmetries can be measured by searching for events with two CP odd or two CP even final states ex: p+p-, K+K-, p0 p0, Ksp0 , ACP sensitivity is about 10-3 @90% C.L. K K vs pp It is also true in phi decay: hep-ph/0511222 BESIII MC simulation Rss Beam constraint Mass BR(KSKS)= (3.60.3)10-6 be accessible at KLOE? =(10.70.8)10-6 Haibo Li, IHEP, BES collaboration

  26. Rare & Forbidden D Decays: FCNC, LFV, LNV Observation of D+ FCNC and lepton number violating decays could indicate new physics. Focus hep-ex/0306049 and G. Burdman PRD66 014009(2002) 3fb-1 Sensitivities 10-6 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+ Vp+ (V  e+e- ) are main backgrounds,, ,  Haibo Li, IHEP, BES collaboration

  27. Access to Semileptonic Weak Decay of J/ (1) • Semileptonic decays: based on heavy quark spin symmetry: • Br (J/  Ds l ) = 0.26  10 -8 ;Br (J/  Ds* l ) = 0.42  10 -8 • A model independent prediction • for the ratio of the above BRs: Z.Phys.C62:271-280,1994 M. Sanchis-Lozano More input from theorists ! Sun S.S et al at BESII are working on the above modes Based on 58 M J/: • The rate of weak decay of J/ is at • 10-8 level, and inclusive search • at BESIII may be available: • J/  D*+S X • D*+S  DS+g (soft g ) • D+S p+ • K*0K+ • KSK+ • ……. G (  DS*+l ) R = ------------  1.5 G(  DS+l ) G (  D*+l ) R = ------------  1.5 G(  D+l ) The sensitivity at BESIII: 10-7 – 10-8 Detail simulations are being done at BESIII. Haibo Li, IHEP, BES collaboration

  28. Access to Weak J/ Decay at BESIII (2) hep-ph/9801202, K. Sharma We need more theoretical input! • J/   DS (DS*) M (M = p, r, ,,’,K, K*,) < G (  DS*+p- ) R = ------------  3.5 G(  DS+p-) 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

  29. Analysis review of BESIII • Charm Physics at threshold at BESIII • Absolute BRs, test of QCD • Decay constants with double tags events • fD+ : 1.5%; fDs : 1.1% with 20 fb-1 data • Form factors and Vcs and Vcd • D mixing at threshold Rmixing : 2.5 10-4 • Direct CP violations: ACP : 10-2 • The sensitivity of rare charm decay 10-7, • at B factories : 10-7 500 fb-1 data • Measurement of Strong Phase cos dD ~ 2% Summary for BESIII • BESIII will provide unique opportunity for open charm physics: • Charm event produced at threshold are very clean with low multiplicity; • Charm events at threshold are pure DD pairs; • Double tag studies are pristine; • Signal/Background is optimum at threshold; • Neutrino reconstruction is clean; • Quantum coherence 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. Haibo Li, IHEP, BES collaboration

  30. Thank you Спасибо Haibo Li, IHEP, BES collaboration

  31. Back-up slides Haibo Li, IHEP, BES collaboration

  32. 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! Could possible EM contribution affect the ratio? Interference effect: 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 Haibo Li, IHEP, BES collaboration

  33. Scan of the resonance region @ 3.7  4.6 GeV(2) Test QCD @ 3.7  4.6 GeV Search for exotic ccbar, Y(4260) Probe gluon enhanced hidden ccbar states Haibo Li, IHEP, BES collaboration

  34. D meson Decay Constants Targeted near threshold at BES Decay is forbidden as ml0 : Helicity suppression The uncertainty of Decay constants: Haibo Li, IHEP, BES collaboration

  35. 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 Haibo Li, IHEP, BES collaboration

  36. Charm As a Probe of Physics Beyond the Standard Model CP asymmetry≤10-3 D0 - D0 mixing ≤10-2 Rare decays ≤10-6 G. Burdman and I. Shipesy hep-ph/0310076 High statistics instead of High Energy Haibo Li, IHEP, BES collaboration

  37. In charm very difficult to calculate the SM rate for rare decays reliably. one of the most reliable: I. Shipsey In the SM R parity violating SUSY B (D+ +e+e) ~ 2 x 10-6 Burdman R-parity violating SUSY: Short distance SM Penguin, W box 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 Haibo Li, IHEP, BES collaboration

  38. Preliminary results of BRs of and • . BES measured the branching fractions for inclusive non-DD-bar decays of (3770) using two different data sample and two different methods Determined from analysis of R values and DD-bar cross sections These are first measurementsby using 33pb-1 @BESII Obtained from fitting to the inclusive hadron and the DD-bar production cross sections simultaneously. Haibo Li, IHEP, BES collaboration

  39. Compare B factories & Charm Factories BFactory 500 fb-1 CFactory 3 fb-1 PDG04 Systematics & Background limited Statistics limited % Error Haibo Li, IHEP, BES collaboration

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