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A narrow pp enhancement near M pp  2m p in J/ y  g pp

A narrow pp enhancement near M pp  2m p in J/ y  g pp. Stephen L. Olsen Univ. of Hawaii. Beijing, China. Representing:. BES. NN bound states (baryonium)??. There is lots & lots of literature about this possibility. deuteron:. baryonium:. attractive nuclear force. attractive force??.

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A narrow pp enhancement near M pp  2m p in J/ y  g pp

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  1. A narrow pp enhancementnear Mpp 2mp in J/ygpp Stephen L. Olsen Univ. of Hawaii Beijing, China Representing: BES

  2. 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 ?

  3. 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

  4. pd5p + ps at rest O.D.Dalkarov et al, PLB392, 229 (1996) [also D.Bridges et al, PLB180, 313(1986)] spectator model M=1870, G=10 resonance included ASTERIX Collab. S.Ahmad, et al Pps(MeV)

  5. 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

  6. The BES Detector EM Shwr counter TOF

  7. Belle sees low-mass pp systems in B decays BppK BD0pp M M pp pp

  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. Are these really p’s & p’s ? p and p in signal region mostly stop in TOF counters in front of the BSC. The p does nothing; the p annihilates. M(pp)<1.9 GeV M(pp)<1.9 GeV Annihilation products that are matched to the p track EBSC(p) EBSC(p)

  10. 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)

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

  12. 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

  13. 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)

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

  15. NG!! D-wave fit?? M=1885 ± ? MeV G < 30 MeV (90% CL) c2/dof=1405/56

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

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

  18. include possible biases as (asymmetric) statistical & systematic errors if what we see is an S-wave resonance: M=1859 MeV/c2 G < 30 MeV/c2 (90% CL) +3 +5 -10 -25

  19. Summary • a large enhancement seen near 2mp in the Mpp distribution for J/ygpp decays. • not apparent in J/ypopp decays • not consistent with any PDG meson state • S- or P-wave can fit data • if it is an S-wave resonance: • Mpeak is below 2mp (M=1859 MeV/c2) • full width is narrow (G<30 MeV/c2) • dN/dcosqg consistent with JPC = 0-+ or0++ • Is this a scalar baryonium partner to the 1--– 1870 MeV state in e+e- and pd annihilations? +3 +5 -10 -25

  20. 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

  21. Comments • 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

  22. 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)

  23. Coulomb effect? phase-space term coulomb factor

  24. BW vs Coulomb

  25. Systematic errors dNevts vary all procedures: fit results don’t change much

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