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J/ y  g pp and gKK

J/ y  g pp and gKK. Zijin Guo Univ. of Hawaii Representing BES Collaboration. Beijing, China. BES. The BES Detector. EM Shwr counter. TOF. World J/ and (2S) Samples (10 6 ). Largest from BES. J/.  (2S). 2002. 2001.

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J/ y  g pp and gKK

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  1. J/y  gpp and gKK Zijin Guo Univ. of Hawaii Representing BES Collaboration Beijing, China BES

  2. The BES Detector EM Shwr counter TOF

  3. World J/ and (2S) Samples (106) Largest from BES J/ (2S) 2002 2001

  4. A narrow pp enhancementnear Mpp 2mp in J/ygpp

  5. NN bound states (baryonium)?? There is lots & lots of literature about this possibility 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 ?

  6. Is there a narrow JPC=1- - pp system near Mpp = 2mp? 2mp e+e-hadrons FENICE e+e-6p DM2 unpub. ppe+e- Bardin etal 2mp Fit: M = 1870 ± 10 MeV G = 10 ± 5 MeV R. Calabrese PEP-N work-shop proceedings

  7. study pp from J/ygpp • C-parity = + • S (P?)-wave (for Mpp 2mp) •  probes JPC= 0-+ (0++?) states • complements ppe+e- and e+e- annihilation • unpolluted (by other hadrons) environment

  8. Use BESII’s 58M J/y decays Select J/ygpp • 4-C kinematic fit • dE/dx for proton id • non-pp bkg small • main bkg from J/yp0pp J/ygpp ???? • J/yghc ; hcpp • (calibration reaction)

  9. Fit signal with an S(P)-wave BW threshold factor keep constant q = daughter momentum q0 = daughter momentum @ peak

  10. Fit to data fitted peak location J/ygpp acceptance weighted BW +3 +5 -10 -25 M=1859 MeV/c2 G < 30 MeV/c2 (90% CL) c2/dof=56/56 0 0.1 0.2 0.3 M(pp)-2mp (GeV) 3-body phase space acceptance

  11. OK! P-wave fit?? M=1876 ± 3 MeV G < 30 MeV (90% CL) M=2mp c2/dof=59/56

  12. cosqg distribution 1+cos2qg (expected for J/yg0-+ ) M(pp)<1.9 GeV sin2qg

  13. Summary (I) if what we see is an S-wave resonance: M=1859 MeV/c2 G < 30 MeV/c2 (90% CL) +3 +5 -10 -25 A narrow pp enhancementnear Mpp 2mp in J/ygpp

  14. not consistent with any PDG meson state • peak below, but near 2mp :baryonium? • narrow width:why solong-lived? • similar patterns seen in baryon-antibaryon systems produced in B meson decays • BppK BppD BpLp BpLcp

  15. Strange & charmed systems B-pLcp- B0pLp- M(Lp)(GeV) (in these cases, the peaking doesn’t seem to be right at threshold) M(Lc+p)(GeV)

  16. Partial Wave Analysis of J/ygKK

  17. Lattice QCD: the ground state scalar glueball should be in the mass range 1.5 – 1.7 GeV • Long history of uncertaintyabout f0(1710) • J/y  gK+K-andgKSKSare very important to investigate the f0(1710)

  18. Data and Analysis Method • Perform separate amplitude analyses for J/y gK+K- gKSKS • Amplitudesarefit to relativistic covariant tensorexpressions (mass range 1-2 GeV) • The maximum likelihood method is employed • Bin-by-bin fit: the data are analyzed independently ineach mass bin (40MeV) Global fit: Breit-Wigner structures + mass, width scan +lnL comparison

  19. TheK+K-andKSKSmass distributions from J/y radiative decay after acceptance and isospin corrections

  20. J/y  gf’2(1525)gf0(1710)gf2(1270)gf0(1500)g+broad 0++ and 2++ Components used in the PWA fit

  21. Bin-by-bin fit Global fit Amplitude intensity

  22. Summary (II) • Using BESII data,partial wave analyseswere done on the K+K- and KSKS systems produced in J/yradiative decay for the mass range 1-2 GeV • KK D- wave intensity shows a clearf’2(1525)signal and the helicity amplitude ratiosx,y appear to be consistent with the theoretical prediction

  23. 25 • Strong production of f0(1710) M = 1740±4±10 MeV Г = 166+5+15 MeV (Global fit) • The non-flat angular distribution in the KK mass region ~1.7 GeV is due to the interference between S- wave and weak D- wave amplitudes • Bin-by-bin fit and global fit give very consistent analysis results -8 -10

  24. Results Bin-by-bin Global

  25. Systematic Error global fit

  26. Study J/yp0pp bkg with MC & data J/yp0pp (data) no peak!! three-body phase space Monte Carlo J/yp0ppgpp (MC) M(pp)-2mp (GeV)

  27. Is Mpeak really less than 2mp? weight events by q0/q: (i.e remove threshold factor) No turnover at threshold peak mass must be <2mp M(pp)-2mp (GeV)

  28. mass determination bias BW “peak” below-threshold mass & widths measurements can be biased when there is background observed peak threshold

  29. could it be a tail of a known resonance? 0-+ resonances in PDG tables: h(1760) M=1760 G = 60 MeV p(1800) M=1801 G = 210 MeV c2/dof=323/58 c2/dof=412/58

  30. Coulomb effect? phase-space term coulomb factor

  31. BW vs Coulomb

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