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Recent J/  Results from BESII

Recent J/  Results from BESII. Xiaobin Ji Representing BES Collaboration Institute of High Energy Physics, CAS Heavy Flavor Physics August 13- 17, 2005, Beijing. Outline. Introduction Multiquark search and study Study of the scalars Study of the excited baryon states

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Recent J/  Results from BESII

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  1. Recent J/ Results from BESII Xiaobin Ji Representing BES Collaboration Institute of High Energy Physics, CAS Heavy Flavor Physics August 13- 17, 2005, Beijing

  2. Outline • Introduction • Multiquark search and study • Study of the scalars • Study of the excited baryon states • Measurements of J/ decays • Measurements of c decays • Summary

  3. Introduction BESII Detector World J/ Samples (×106) BESII 58MJ/ J/ • VC: xy = 100 m TOF: T = 180 ps • MDC: xy = 220 m BSC: E/E= 21 % • dE/dx= 8.5 %  = 7.9 mr • p/p=1.78(1+p2) z = 2.3 cm • counter: r= 3 cm B field: 0.4 T z = 5.5 cm

  4. New Observation of X(1835) in at BESII

  5. Phys. Rev. Lett. 91, 022001 (2003) Observation of an anomalous enhancement near the threshold of mass spectrum at BES II J/ygpp BES II acceptance weighted BW +3 +5 -10 -25 M=1859 MeV/c2 G < 30 MeV/c2 (90% CL) X(1860) c2/dof=56/56 0 0.1 0.2 0.3 3-body phase space M(pp)-2mp (GeV) acceptance

  6. X(1860) from BES has large BR to pp • BES measured: • For a 0-+ meson: • So we would have: (This BR to pp might be the largest among all PDG particles) Considering that decaying into pp is only from the tail of X(1860) and the phase space is very small, such a BR indicates X(1860) has large coupling to pp !

  7. pp bound state (baryonium)? There is lots & lots of literature about this possibility • E. Fermi, C.N. Yang, Phys. Rev. 76, 1739 (1949) • … • I.S. Sharpiro, Phys. Rept. 35, 129 (1978) • C.B. Dover, M. Goldhaber, PRD 15, 1997 (1977) • … • Datta, P.J. O’Donnell, PLB 567, 273 (2003)] • M.L. Yan et al., hep-ph/0405087 • B. Loiseau et al., hep-ph/0411218 • … deuteron: baryonium: attractive nuclear force attractive force? + n + - loosely bound 3-q 3-q color singlets with Md = 2mp- e loosely bound 3-q 3-q color singlets with Mb = 2mp-d ? Observations of this structure in other decay modes are desirable.

  8. BES: X(1835) in X(1835) 5.1  X(1835) 6.0  BES II Preliminary

  9. Combine two channels 7.7 Statistical Significance 7.7  X(1835) BESII Preliminary BESII Preliminary hep-ex/0508025

  10. X(1835) could be the same structure as X(1860) indicated by pp mass threshold enhancement • X(1835) mass is consistent with the mass of the S-wave resonance X(1860) indicated by the pp mass threshold enhancement. Its width is 1.9 higher than the upper limit of the width obtained from pp mass threshold enhancement. • On the other hand, if the FSI effect is included in the fit of the pp mass spectrum, the width of the resonance near pp mass threshold will become larger.

  11. Fit to J/ pp including FSI M = 1830.6  6.7 MeV  = 0  93 MeV Include FSI curve from A.Sirbirtsev et al.(hep-ph/ 0411386) in the fit (I=0) BES II Preliminary In good agreement with X(1835)

  12. X(1835) could be the same structure as pp mass threshold enhancement. • It is likely to be a pp bound state since it dominantly decays to pp when its mass is above pp mass threshold. • ’ mode is expected to be the most favorable decay mode for a pp bound state below pp mass threshold G.J. Ding and M.L. Yan, hep-ph/0502127

  13. Observation of an anomalous enhancement near the threshold of mass spectrum at BES II BES II 3-body phase space For a S-wave BW fit: M = 2075 12  5 MeV Γ = 90  35  9 MeV Phys. Rev. Lett. 93, 112002 (2004)

  14. Observation of a strong enhancement near the threshold of mass spectrum at BES II NX* BES II PS, eff. corrected (Arbitrary normalization)

  15. A strong enhancement is observed near the mass threshold of MKat BES II. • Preliminary PWA with various combinations of possible N* and Λ* in the fits —— The structure Nx*has: Mass 1500~1650MeV Width70~110MeV JP favors 1/2-  consistent with N*(1535) (or it is an new NX*?) The most important is: It has large BR(J/ψ  pNX*) BR(NX* KΛ)2 X 10-4 , suggesting NX*has strong coupling to KΛ. indicating it could be a KΛ molecular state (5 - quark system).

  16. Study of the scalars • There have been hot debates on the existence of  and. • Lattice QCD predicts the 0++ scalar glueball mass in the range 1.5 - 1.7 GeV. f0(1500) and f0(1710) are good candidates.

  17. study  in study  in • studyf0(980), f0(1370), f0(1500), f0(1710)and f0(1790)in 0++

  18. The study of  • evidence for a low mass pole in the early DM2 and BESI data on J/   . • huge event concentration in the I=0 S-wave  channel seen in M~ 500 – 600 MeV in the pp central production exp. • to explain  scattering phase shift data， should be introduced in chiral perturbative theory. • FNAL E761 exp. D++-+ data

  19. The  pole in at BESII 0  M(+-0) M()   M(+-)

  20. Fit results: I II Averaged pole position: MeV Phys. Lett. B 598 (2004) 149

  21. The study of  • A possible  pole is controversial. • Some analyses of LASS K scattering data need (800), some don’t. • Scadron et al. favors a nonet made up of , (800), f0(980) and a0(980). • Julich group used t-channel exchanges to explain K scattering data. • evidence of  in FNAL E791 data on D+ K-++ • slightly lower statistics of CLEO D0 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

  22. κ hep-ex/0506055 Submitted to PLB

  23. BES Preliminary κ K*0(1430)

  24. Study of other scalars • Lattice QCD: • the lightest scalar glueball in the region of 1.5- 1.7 GeV • Glueball searches should be performed in • simultaneously.

  25. f0(980) • Important parameters from PWA fit: • Large coupling with KK indicates big component in f0(980) f0(980) f0(980) Phys. Lett. B 607 (2005) 243

  26. f0(1370) • There has been debate whether f0(1370) exists or not. • f0(1370)clearly seen in J/  , but not seen in J/  . f0(1370) NO f0(1370) PWA 0++ components Phys. Lett. B 607 (2005) 243

  27. f0(1710) • Clear f0(1710) peak in J/  KK. • Nof0(1710) observed in J/   ! f0(1710) NO f0(1710) Phys. Lett. B 603 (2004) 138

  28. PWA analysis shows one scalar. Phys. Rev. D 68 (2003) 052003

  29. New f0(1790)?? • A clear peak around 1790 MeV is observed in J/  . • No evident peak in J/  KK. If f0(1790) were the same as f0(1710), we would have: Inconsistent with what we observed in J/   , KK f0(1790) ?  f0(1790) is a new scalar ??

  30. Scalars in J/   Two scalars in J/  : • One is around 1470 MeV, may be f0(1500)? • The other is around 1765 MeV, is it f0(1790) or f0(1710) or a mixture of f0(1710) and f0(1790)? BES II Preliminary

  31. Excited baryon states • Probe the internal structure of light quark baryons • Search for missing baryons predicted by quark model

  32. Pure isospin 1/2 Feynman diagram of the production of For and , and systems are limited to be pure isospin 1/2.

  33. The evidence of 2 new N* peaks N*(1520) N*(1535) N*(1650) N*(1675) N*(1680) N*(1440)? ? Missing mass spectrum (GeV/c2)

  34. Fitting formula : momentum of : proton momentum in Mx frame ► Possible new N* resonance ►preliminary PWA shows: this N* favors 3/2+ hep-ex/0405030

  35. Measurements of J/ and c decays

  36. Measurement of J/ decays to Vector + Pseudoscalar --- channels measured:

  37. The measured branching ratios Phys. Rev. D 71 (2005) 032003

  38. First measurements of J/ 2(+-) and 3(+-) J/ 3(+-) J/ 2(+-)   M() GeV M() GeV Phys. Lett. B 610 (2005) 192

  39. Measurement of J/ decays to  + Pseudoscalar ---

  40. BES II Preliminary

  41. First observation of cK+K-2(+-) and 3(+-) Submitted to Phys. Lett. B (hep-ex/0505093)

  42. Summary • New Observation of X(1835) in • Observation of an anomalous enhancement near the threshold of and in •  pole obtained in J/ •  pole obtained in J/K*K and KK • the parameters of f0(980) are determined • f0(1370), f0(1500), f0(1710) and f0(1790) studied. • scalar puzzle? Further study needed. • N(2065) observed, favors 3/2+ • New measurements of J/ and c decays

  43. Thank you! 谢谢！

  44. OZI rule and flavor tagging in J/ hadronic decays • In J/ hadronic decays, an  or  signal determinesthe or component, respectively. OZI rule

  45. Unusual properties of f0(1370), f0(1710) and f0(1790) • f0(1710): • It dominantly decays to KK (not to )  • It is mainly produced together with  (not )  • What is it ? • f0(1370) and f0(1790) • They dominantly decays to  (not to KK)  • It is mainly produced together with  (not )  • What are they ? Scalar Puzzle

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