1. Results from BESII and Prospects at BESIII Weiguo LI (Representing BES Collaboration) Institute of High Energy Physics, Beijing Sep. 3, 2009, Beijing, China

2. Outline Introduction Results from BESII (selected topics) – Results on light hadron spectroscopy – R measurement – Non-DD decays and the line shape of the hadron cross section Physics at BESIII Summary

3. 3 Linac Storage ring BES BSRF Beijing Electron Positron Collider (BEPC) at IHEP

4. 4 BES 1-2.3GeV e+ e- collisions produce charmonium states （ J/  ，  (2S) ，  cJ and  (3770) etc.), charm mesons and  lepton. beam energy: 1.0 – 2.3(2.5) GeV Physics goal 4 （ BEPC/BES ）

5. We are unique now in  -charm region  In transition region between pQCD and non-pQCD. 5 From PDG Physics at BEPC/BES

6. 6  Study of Light hadron spectroscopyStudy of Light hadron spectroscopy  search for non-qqbar or non-qqq states  meson spectroscopy  baryon spectroscopy  Study of the production and decay mechanisms ofStudy of the production and decay mechanisms of charmonium states: charmonium states: J/ ,  (2S),  C (1S),  C{0,1,2},  C (2S), h C ( 1 P 1 ),  (3770), etc. New Charmonium states above open charm threshold.  Precise measurement of R valuesPrecise measurement of R values  Precise measurement of CKM matrixPrecise measurement of CKM matrix  Search for DDbar mixing, CP violation, etc.Search for DDbar mixing, CP violation, etc. Physics Topics at BES

7. 7 Study of the spectroscopy – a way of understanding the internal structure glueball spectrum from LQCD Y. Chen et al., PRD 73 (2006) 014516 7 Motivation:  Establish spectrum of light hadrons  Search for non-conventional hadrons  Understand how hadrons are formed  Study chiral symmetry in QCD Why at a  -charm collider ?  Gluon rich  Larger phase space than at higher energies  Clean environment, J PC filter Many results in BESII: ~ 50 publications Much more from BESIII:  100 statistics,  10  resolution

8. New forms of hadrons  Hadrons consist of 2 or 3 quarks ： Naive Quark Model ：  QCD predicts the new forms of hadrons: Multi-quark states ： Number of quarks > ＝ 4 Hybrids ： qqg ， qqqg … Glueballs ： gg ， ggg … Meson （ q q ） Baryon （ q q q ）

9. Multi-quark states, glueballs and hybrids have been searched for experimentally for a very long time, but none is established. The observation of the new forms of hadrons will be a direct test of QCD. This has been one of the important physics goals for many experiments.

10. Charmonium physics What to study ? –Production, decays, transition, spectrum For what ? –A lab for pQCD and non- pQCD –Calibrate LQCD –How quarks form a hadron ? Why at a tau-charm collider ? –A clean environment –Tagging possible –Abundantly produced Examples of interesting/long standing issues:  puzzle Missing states ? Mixing states ? New states above open charm thre.(X,Y,Z,…)

11. 11 R : one of the most important and fundamental quantities in particle physics. R measurement Why precise R important? Essential for precise tests of SM.  the global fit of Higgs mass  anomalous  magnetic moment from g-2

12. Precise measurement of CKM elements -- Test EW theory Precise measurement of CKM elements -- Test EW theory CKM matrix Three generations of quark? Unitary matrix?  5% precision  10% precision Expect precision < 2% at BESIII Precision of measurement CKM matrix elements -- a precise test to SM ！ New physics beyond SM? Precision of measurement CKM matrix elements -- a precise test to SM ！ New physics beyond SM? 12 CKM matrix elements are fundamental SM parameters that describe the mixing of quark fields due to week interaction.

13. Decays constants vs LQCD 2.3  difference for f Ds. Real ? BESIII may resolve this issue, reach the precision of LQCD.

14. CP violation is regarded as the origin of asymmetry of the matter and anti-matter. CP violation predicted by theoretical models is not big enough to describe the asymmetry. CP violation is observed in K and B decays, but has never been in charm sector. CP violation and mixing 0 0 e + e -   (3770)  D 0 D 0 At BESIII, the sensitivity of the mixing rate: 1.5  10 -4 mixing : a good place to search for CP violation In SM, the mixing is very small. 14

15. 15 BESII @ BEPC 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

16. 16 BESI: run from 1989-1998 BESII: run from 1999-2004 L ~ 5  10 30 / cm 2  s at J/  E beam ~ 1 – 2.5 GeV BESII data samples DataBESIICLEOc J/  58 M--  (2S) 14 M27 M  (3770) 33 pb -1  800 pb -1

17. A structure at 2175MeV was observed in e + e -   ISR  f 0 (980), e + e -   ISR K + K - f 0 (980) initial state radiation processes Observation of a new 1 -- resonance Y(2175) at BaBar Phys. Rev. D 74 (2006) 091103(R) Phys. Rev. D 76 (2007) 012008 Y(2175) 6.2  Y(2175)  (1680)

18. BESII: Y(2175) in J/    f 0 (980)   f 0 (980) Final states:   ,   K + K -, f 0 (980)   +  - Define , , f 0 (980) signal and sideband regions. Phys. Rev. Lett., 100, 102003 (2008)

19. M =2.186±0.010 GeV/c 2  =0.065±0.023 GeV/c 2 N events = 52  12 5.5  M(  f 0 (980)) GeV/c 2 A peak around 2175 MeV/c 2 is observed in J/    f 0 (980)

20. 20 BELLE: e + e -   ISR   +  - Φ(1680) Fit results: Belle: I. Adachi et al., arXiv:0808.0006 M(Y(2175)) = 2133 +69 -115 MeV/c 2 Γ(Y(2175))= 169 +105 -92 MeV/c 2 M(Φ(1680)) = 1687  21 MeV/c 2 Γ(Φ(1680)) = 212  29 MeV/c 2 Two(+1 for third peak) coherent BW One BW interfering with non-resonant 673 fb -1

21. What is Y(2175)? Some theoretical interpretations:  A conventional state?  An analog of Y(4260) ( )?  An 4-quark state? More experimental information needed. To understand the nature of Y(2175), we are now working on J/  K*K*, ,  KK, …

22. BESII: Y(2175) in J/  K *0  K *0 ? B(J/  K*  K*)=(7.7  0.8  1.4)  10 -4 First measured. M(K +  - ) M(K -  + ) K* M(  ) 

23. M(K*  K*) 3-body phase space background K *0  K *0 invariant mass in J/  K *0  K *0 Upper limit @ 90% C.L. B(J/  Y(2175))B(Y(2175)  K*  K*) < 2.52  10 -4

24. 24 The observation of new N* peaks in Missing mass spectrum (GeV/c 2 ) N*(1440)? N*(1520) N*(1535) N*(1650) N*(1675) N*(1680) ?

25. 25 Phys. Rev. Lett. 97 (2006) 062001 N*(2065) BW fit yields: PWA is performed. well-established N*’s are fixed to PDG values. for N*(2065), L=1 is much worse than L=0 in the fit.  1/2 + or 3/2 + (improve log likelihood by 400) 1/2 + + 3/2 + (improve log likelihood further by 60)

26. BESII: PWA of M  00  M 2 (p  0 )

27. Resonances used in the PWA

28. Comparison of data with fit results + : data hist.: fit

29.  N(1440), N(1520), N(1535), N(1650), N(1675), N(1680), N(1710) are needed.  Nx(2065) exists in this channel (stat. sig. >>5σ) The spin-parity favors 3/2+ N*M(MeV/c 2 )  (MeV/c 2 ) JPJP fraction(%) 1/2+9.74~25.93 2.38~10.92 6.83~15.58 6.89~27.94 4.17~30.10 23.0~41.8 3/2- 1/2- N(1710)1/2+0.54~3.86 3/2+ N(1440)1.33~3.54 N(1535)0.92~2.10 N(1650)0.91~3.71 N(1520)0.34~1.54 N(2065)0.91~3.11 Br (×10 -4 )

30. Observation of charged  at BESII   was first found in K  scattering data  However, its phase shift is much less than 180 o and it cannot be filled into any nonets of ordinary mesons.  There have been hot debates on the existence of . In recent years:  FNAL E791 found evidence of neutral  in D +  K -  +  +  CLEO D 0  K -  +  0 data find no evidence of   FOCUS data on K +  K -  +  + require K* 0 interfere with either a constant amplitude or a broad 0 + resonance in K   BESII observed neutral  in J/   K* 0 K   K  K   neutral  pole:

31. CLEO reported the necessity of in However, no charged  is needed in BABAR data. Charged  is observed at BESII in The existence of charged  is expected ! M(K   0 ) GeV/c 2 BESII Preliminary  Different parameterizations of  are tried in PWA. Consistent results on the pole of charged  are obtained.  The pole position for charged  is consistent with that for neutral  within the error.  K*(1410), K*(1430)

32. First observation of  (2S)  +   This decay mode is thought to be mainly produced from the annihilation of three gluons into ss pair.  Statistical significance ~ 5  M M  BESII preliminary X,Y,Z type of particles in ss system ? Hint: Y(2175) ? BESIII will answer these questions with help from theorists

33. Resonance parameter fit Heavy charmonia parameters were fitted with the data between 3.7–5.0GeV, taking into accounts the phase angles, interference, energy-dependent width, etc. Phys. Lett. B660, (2008)315 Probability =31.8%

34. Fitting Results Comparison Phys. Lett. B660 (2008) 315-319

35. 35  (3770) non-DD decays  (3770) decays most copiously into DD.  (3770) is a mixture of the 1 3 D 1 and 2 3 S 1, other  (2S)-like decays for  (3770) are expected. (mixing angle 12  2 o ). Many theoretical calculations estimate the partial width for  (3770)   +  - J/ . (Lipkin, Yan, Lane, Kuang, Rosner) Kuang obtained a partial width for  (3770)   +  - J/  in the range of 25 -113 keV. (Y.P. Kuang, PRD 65 (2002) 094024)

36. 36 BES first reported  (3770) non-DD decay  (3770)   +  - J/  Open histogram is for e + e -, histogram in yellow is for  +  - mainly The histogram is  ’ error bars are  ’+  ’’ data MC 20 times large than the data hep-ex/0307028 PLB 605 (2005) 63 27.7 pb -1

37. Anomalous LineShape of  [e + e -  Hadrons] in energy region from 3.650 to 3.872 GeV Phys.Rev.Lett101,102004,2008 Two data sets taken in March and December 2003 2. Significance of the interference between the two amplitudes is 3.6  1. Significances of the two amplitudes are more than 7  3. The hypothesis of  (3770) amplitude +G(3900) and interference does not significantly improve the fit from the one  (3770) amplitude hypothesis A fine scan in this area at BESIII is needed!

38. 38 Previous exps:  R/R  15 % below 5 GeV 1998-1999, BESII measured 6+85 points R values in 2-5 GeV region.  R/R  6 % Phys. Rev. Lett., 88 (2002) 101802 R Measurement

39. In 2003, from a dedicated  (3770) scan data, the R values at 68 energy points from 3.650- 3.872 GeV were measured. stat. error:  3-4% syst. error:  4% Phys. Rev. Lett., 97 (2006) 262001

40. R values at 2.6, 3.07 and 3.65 GeV measured with the precision of about 3.5% at BESII in 2008. The running coupling constant  s (s) was determined

41. In the 1990s, there was discussion of the future. The conclusion was to continue tau-charm physics with a major upgrade of the accelerator and detector (BEPCII/BESIII). Officially approved in 2003. The physics window is precision charm physics and the search for new physics. –High statistics: high luminosity machine + high quality detector. –Small systematic error: high quality detector. BEPCII/BESIII

42. BEPC II Storage ring: BEPC II Storage ring: Large angle, double- ring RF SR IP Beam energy: 1.0-2.3GeV Luminosity: 1×10 33 cm -2 s -1 Optimum energy: 1.89 GeV Energy spread: 5.16 ×10 -4 No. of bunches: 93 Bunch length: 1.5 cm Total current: 0.91 A SR mode: 0.25A @ 2.5 GeV

43. 43 Main parameters achieved in collision mode parametersdesignAchieved BERBPR Energy (GeV)1.89 Beam curr. (mA)910650700 Bunch curr. (mA)9.8>10 Bunch number93 RF voltage1.5  s @1.5MV 0.0330.032  x * /  y * (m) 1.0/0.015~1.0/0.016 Inj. Rate (mA/min) 200 e   50 e + >200>50 Lum. (10 33 cm -2 s -1 )10.30

44. 44 BESIII @ BEPCIIBESII @ BEPC BESIIIBESII MDC  p /p = 0.5%@1GeV,  dE/dx = 6%0.5%@1GeV  p /p =2.5%@1GeV,  dE/dx = 8%=2.5%@1GeV TOF90 ps(Barrel)180 ps (Barrel) EMC  E = 2.5% @1GeV  E = 22% @1GeV MUC9 for barrel, 8 for endcap3 layers for barrel Magnet1.0 T0.4 T acceptance ~ 93%

45. Europe (8) GSI, Germany University of Bochum, Germany University of Giessen, Germany KVI/University of Groningen, Netherland INFN, Laboratri Nazionali di Frascati University of Torino, Italy JINR, Dubna, Russia Budker institute of Nuclear Physics Russia 45 Others in Asia(3) Tokyo University Seoul National Univ. Univ. of Punjab, Lahore USA (6) University of Hawaii University of Washington Carnegie Mellon University Univ. of Minnesota University of Rochester Indiana University China (25) IHEP, CCAST, GUCAS ， Univ. of Sci. and Tech. of China Shandong Univ., Zhejiang Univ. Huazhong Normal Univ., Wuhan Univ. Zhengzhou Univ., Henan Normal Univ. Peking Univ., Tsinghua Univ., Zhongshan Univ.,Nankai Univ. Shanxi Univ., Sichuan Univ Hunan Univ., Liaoning Univ., Huangshan College. Nanjing Univ., Nanjing Normal Univ. Guangxi Normal Univ., Guangxi Univ. Hong Kong University Chinese Univ. of Hong Kong Totally 42 institutions

46. BESIII commissioning and data taking milestones Mar. 2008: first full cosmic-ray event April 30, 2008: Move the BESIII to IP July 20, 2008: First e + e - collision event in BESIII Nov. 2008: ~ 14M  (2S) events collected April 14, 2009 ~100M  (2S) events collected May 30, 2009 ~42 pb -1 at continuum collected (3.65 GeV) July 28, 2009 ~200M J/  events collected Machine luminosity Peak Lumi. @ Nov. 2008: 1.2  10 32 cm -2 s -1 Peak Lumi. @ May 2009: 3.2  10 32 cm -2 s -1

47. First collision event on July 19, 2008

48. June 12 – Jul. 28 Mar. 6 – April 14May 24 – June 2  100 M  (2S) data  200 M J/  data  42 pb -1 data at 3.65 GeV Data accumulated at BESIII

49. 49 Statistics at BESIII at designed peak Luminosity (assuming 10 7 s data taking time each year) Physics Energy (GeV) Peak Luminosity (10 33 cm –2 s –1 ) Events/yearExisting data J/  3.097 0.6 10×10 9 60×10 6 (BESII) 200×10 6 (BESIII)  3.67(?) 1.0 12×10 6 --  ’ 3.686 1.0 3×10 9 27 ×10 6 (CLEOc) 14 ×10 6 (BESII) 100 ×10 6 (BESIII) D 3.77 1.0 30×10 6 5×10 6 (CLEOc) Ds 4.03 0.6 1×10 6 4×10 3 (BESI) Ds 4.17 0.6 3×10 6 0.3×10 6 (CLEOc) R scan 3.0-4.6 0.6(?)-1.0 --

50. Detector performance and calibration ● Layer 7 ● Layer 22 Wire reso. Design: 130  m dE/dx reso.: 5.80% Design：6-8% CsI(Tl) energy reso. Design: 2.5%@ 1 GeV Barrel TOF reso.: 78 ps Design：80-90 ps Bhabha

51. EM transitions: inclusive photon spectrum  c2  c1  co  c1,2   J/  cc BESIII preliminary

52. Some physics signals  signal Red: K* Blue:  K*  0 signal  signal BESIII preliminary

53.  ’   l + l - : signals of  cJ,  0 and  BESIII preliminary

54.  (2S)   cJ BESIII preliminary

55. Structures in  c0   +  - K + K - at BESIII BESII: PRD72, 092002 BESIII preliminary

56. Observation of h c : E1-tagged  (2S)   0 h c,h c   c Select E1-photon to tag h c A fit of D-Gaussian signal + sideband bkg. yield: M(h c ) Inc = 3525.16±0.16±0.10 MeV  (h c ) Inc = 0.89±0.57±0.23 MeV First measurement Br(  ’    h c )×Br(h c   c ) Inc =(4.69±0.48(stat)) ×10 -4 (  (h c ) floated) =(4.69±0.29(stat)) ×10 -4 (  (h c ) fixed at  (  c1 )) background subtracted Systematic errors under study CLEO’s results (arXiv 0805.4599v1) : M(h c ) Inc = 3525.35±0.23±0.15 MeV Br(  ’    h c )×Br(h c   h c ) Inc =(4.22±0.44±0.52) ×10 -4 (  (h c ) fixed at  (  c1 ) ~ 0.9MeV CLEOc: Combined E1-photon-tagged spectrum and exclusive analysis M(h c ) avg = 3525.28±0.19±0.12 MeV Br(  ’    h c )×Br(h c   h c ) avg =(4.19±0.32±0.45) ×10 -4 BESIII preliminary N(h c )= 2540±261  2 /d.o.f = 39.5/41.0 BESIII preliminary

57. Observation of h c : Inclusive  (2S)   0 h c Select inclusive  0 A fit of D-Gaussian signal + 4 th Poly. bkg yield N(h c ) = 9233±935,  2 /d.o.f = 38.8/38.0 Combined inclusive and E1-photon-tagged spectrum Br(  ’    h c ) =(8.42±1.29(stat)) ×10 -4 (First measurement) Br(h c   c ) =(55.7±6.3(stat))% First measurement 57 background subtracted Inclusive   recoil mass spectrum Systematic errors under study BESIII preliminary

58. BR (10 -3 )  c0  c2 0000 BESIII3.25±0.03(stat)0.86±0.02(stat) PDG2. 43±0.200.71±0.08 CLEO-c2.94±0.07±0.350.68±0.03±0.08  BESIII3.1±0.1(stat)0.59±0.05(stat) PDG2.4±0.4<0.5 CLEO-c3.18±0.13±0.350.51±0.05±0.06 CLEO-c arxiv:0811.0586 Study of  (2S)→  0  0,  (  → ,  0 →  ) Interesting channels for glueball searches Based on 110M  (2S) BK study from 100M inclusive MC sample and 42pb -1 continuum sample Unbinned Maximum Likelihood fit: –Signal: PDF from MC signal –Background: 2 nd order Poly.  2S)   0  0 N  c0 16645±175 N  c2 4149±82  2S)   N  c0 1541±56 N  c2 291±23

59. Confirmation of the BESII observation: pp threshold enhancement in J/  decays  PRL 91 (2003) 022001 BES III preliminary  (2S) →  J/  M=1864.6 ± 5.3MeV/c 2  < 33 MeV/c 2 (90% CL) M=1859 MeV/c 2  < 30 MeV/c 2 (90% CL) +3 +5  10  25 0.3 BES II M(pp)-2m p (GeV)

60. Confirmation of BESII observation: No pp threshold enhancement in  (2S) decays  No significant narrow enhancement near threshold (~2  if fitted with X(1860)) M pp (GeV) BES III preliminary PRL 99 (2007) 011802 BES II No enhancement in  ’ decays In fact, no enhancement in  ’ decays or in the process of J/    pp shows that FSI unlikely

61. Study of  cJ  VV (V= ,  )  cJ    cJ   First measurement of  c1   and  First measurement of  cJ    cJ   BESIII preliminary M(  ) M(  ) M(  )

62. BESII data  58M J/  BESIII MC  58M J/  X(1835) > 10  X(1835)  6  MC simulation: X(1835) at BESIII

63. BESII data  58M J/  BESIII MC  58M J/  X(1835) > 10  X(1835)  5.1 

64. assuming 2.5  BESII J/  events J/  a 0 (980),  a 2 (1320),  (1390),  a 2 (1700) are included. the spin-parity of each component as well as the interference between them are considered. background included (estimated from sideband, about 10%) a full PWA is performed. Search for 1 -+ in J/  0  0 (MC)

65. Comparison of generated data and PWA projections M(  0 ) GeV/c 2

66. input outputinput output input output a 2 (1320)1318 1320  2 107 112± 420.8419.49± 0.80  1 (1400) 1376 1380  8 360 376±1614.5714.66± 1.30 Mass(MeV/c 2 ) Width(MeV/c 2 ) Fraction(%) Input/output check

67. Data taking plan in the near future   (3770) scan to study non-DD decay, the precise energy measurement system should be ready  Taking larger data sample of J/ , and  (2S)  Taking large data sample at  (3770)

68. Assuming that there are interference between the two amplitudes With BES previously measured cross sections for DD production. Phys. Lett. B 641, 145(2006)

69. Inclusive hadrons  Branching fractions Phys.Rev.Lett.97: 121801(2006) Mainly due to vacuum polarization corrections  Resonance parameters Better than PDG world average First observed this effects!

70. CLEO  (3770) non-DDbar decays  +     c0  ’’  XJ/  : missing event energy (GeV) after finding  +,  -, J/  (  ll) e + e -  ’   (J/  +  - )  ’’  J/  +  -  ’’  cJ :  cJ  J/  :  cJ  hadrons:  (  (3770)  hadrons) (6.5  0.1 +0.4 -0.3 ) nb  (  (3770)  DD) (6.39  0.10 +0.17 -0.08 )nb  (  (3770)  non-DD) (-0.01  0.12 +0.40 -0.33 )nb translates into BR UL B(  (3770)  non-DD) < 10% Exclusive channels: ModeBR (%)  +   J/  0.189  0.020  0.020  0  0 J/  0.080  0.025  0.016  J/  0.087  0.033  0.022  c0 0.73  0.07  0.06  c1 0.39  0.14  0.06  (3.1  0.6  0.3)  10 -2  other ~2  (3770)  non-DD decay is very interesting ， needs results from BESIII to finally decided 。

71. Challenges in BESIII Physics Analyses personal view  New ideas in BESIII Physics, although There is a nice guidance for BESIII Physics (yellow book), new ideas are very important. Theorists – experimentalists  To collect large data samples with good data quality There are some difficult problems to solve: -- Machine backgrounds and noise: adding more masks; adjusting detector setting (MDC); solving problems when they occur. arXiv: 0809.1869

72. -- Gradually increase the machine luminosity and stability of the machine, last time the luminosity is 20%, 10% of the designed luminosity at  (2S), J/ , still a long way to reach designed luminosity, More currents(vacuum, RF power?); Better tuning of the machine, …; Hardware improvement if needed; Beam energy is estimated to reach 2.3 GeV, but it needs to be tested;  Develop physics analysis tools: partial wave analysis, Dalitz plot analysis, etc.  Improve software and understand the detector: calibration, alignment, simulation, data/MC comparison. It is important to reduce the systematic errors, as for some physics, the systematic errors are already dominant.

73. Prospects: a bright future Usually each year, BESIII should take data 5-6 months, SR 3-4 months, BESIII will resume data taking after summer shutdown, ~5 months until next summer Possible plans: –500-1000 M J/  events (2-4 months) –500-1000 M  (2S) (2-4 months) –2fb -1  (3770) (4 months) –Lineshape scan of  (3770) (2 weeks) Expecting new and exciting results from new data To be decided in Nov. 2009

74. Thanks

75. mixing & strong phase Tag one D 0 in CP eigenstate, the other side is a mixture of and Rate  B 1 B 2 (1+2rcos  ) A global fit with inputs of –Yield of each channel(ST & DT) –BG from MC + PDG –Results from Babar, Belle, CDF, E791, Focus & CLEO Output: CLEO Hadronic Single Tags D. M. Asner and W.M. Sun, Phys. Rev. D73, 034024 (‘06) and Phys. Rev. D77, 019901 (E) (‘08); W. M. Sun, NIMA 556, 326 (’06) Quantum correlation DDbar mixing described by: x=  M/  y  R M =(x 2 +y 2  Actually measured x’ = xcos  + ysin  y’ = -xsin  + y cos 

76. Phys. Rev. Lett. 100, 221801 (’08) Phys. Rev. D78, 012001 (’08) CLEO Based on 281 pb -1 at  (3770) Still limited by statistics Future: –More statistics: 818 pb -1 in hands –More semileptonic channels to better constrain y At BESIII: – will collect ~15 fb -1 in a few years –Muon ID: better in channels such as K  First determination of cos 

77. mixing: where are we now ? We know there is a mixing, but Consistent with SM ? –Quark level: much too small –Hadron level: not calculable yet Consistent with NP ? –Yes, with many models What’s next ? –Integrate all flavor physics results –Correlate with other mixing results –More rare decay/CPV limits to constrain NP models no mixing excluded at 9.8σ http://www.slac.stanford.edu/xorg/hfag/charm ICHEP08 BESIII can provide valuable information

78. Search for CP violation CP violation in D0- D0bar mixing CP violation in direct decay (direct CP violation) CP violation from the interplay of decay and mixing (indirect CP violation) consistent with CP conservation http://www.slac.stanford.edu/xorg/hfag/charm

79. CP violation in direct decays CPV in D and D s decays CPV in Cabibbo suppressed D (s) decays 281 pb -1 PRD 76, 112001 (’07) 298 pb -1 PRL 100, 161804 (’08) PRD 78, 072003 (’08) No observed asymmetry, integrated over phase space: ACP = (-0.03  0.84  0.29)% Or in specific two-body amplitudes Still far away from SM expectations (< 10 -3 ) BESIII can touch it CLEO