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Radiative Decays and Glueball Searches by Shan JIN at ICHEP2002

Explore the search for glueballs through radiative decays, with a focus on observations from BES II, CLEO, and L3 experiments in the mass regions of interest. Preliminary results and comparisons are presented. Gain insights on the identification of glueball candidates and possible decay modes.

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Radiative Decays and Glueball Searches by Shan JIN at ICHEP2002

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  1. Radiative Decaysand Searches for Glueballs Shan JIN Institute of High Energy Physics (IHEP) Beijing, P.R.China jins@mail.ihep.ac.cn July 24-31, 2002 ICHEP2002, Amsterdam

  2. Outline • PWA of , at BES II • Observation of an enhancement near threshold in at BESII • Anti-search for glueball candidates in two photon collisions at CLEO and L3 • Summary

  3. PWA of , at BES II

  4. Introduction QCD predicts the existence of glueballs. Radiative decays are suggested as promising modes of glueball searches.

  5. Lattice QCD:The ground scalar glueball should be in the mass range 1.5 – 1.7 GeV. • Long history of uncertainty on

  6. PWA of and .

  7. Global fit and bin-by-bin fit are performed BES II Preliminary

  8. Preliminary Results( ) • Clear signal. • Evidence of . • 0++ is dominant in 1.7GeV mass region • Masses and Widths (statistical error only): MeV, MeV. MeV, MeV.

  9. PWA of .

  10. Preliminary Results ( ) • well known f2(1270) • two 0++ at around • 1.4 and 1.7 GeV • mass regions, • for f0(1710):

  11. Observation of an enhancement near threshold in at BESII

  12. Event Selection • 2 good charged tracks • (isolated from charged tracks) • Particle ID • 4C-fits

  13. pp masses for selected events Besides peak, there is a clear enhancement near threshold.

  14. Are these really and ’s? (Yes!) signal p? p? CLpid CLpid Tagged p & p from J/X-X+ Tagged K+& K-from J/K*+K- p p K- EBSC K+ EBSC CLpid CLpid CLpid CLpid EBSC EBSC EBSC EBSC

  15. Backgrounds Main backgrounds remained after selection for the mass peak near threshold(almost equal contribution): • phase space No clear enhancement near threshold

  16. S-wave Breit-Wigner function If the enhancement is treated as a resonance: q = daughter momentum q0 = daughter momentum @ peak Weight the BW function with mass-dependent acceptance

  17. BW fit to the structure near threshold • Background shape from MC • Preliminary results: (statistical error only) Statistical significance: ~

  18. What is it? • molecular state? • glueball? why so close to ? • Dynamical effect? no evidence in or • ???? Searches for other decay modes

  19. Anti-search for glueball candidates in two photon collisions at CLEO and L3

  20. of a glueball is expected to be very small. A state which is observed in a gluon rich environment but not in two photon fusion has the typical signature of a glueball • Both experiments studied

  21. Results from L3 • The tensor meson • The 2230 mass region (assume )

  22. Results from L3 (continued) • The 1750 MeV mass region wave dominant

  23. Results from CLEO • Assume J=2:

  24. Summary • PWA ofBES II 58M data show strong production of in with . • A significant near-threshold enhancement is observed in at BES II. If treated as a resonance: • In at L3 and CLEO:

  25. Status of at BES II • So far, no clear signal of has been observed. • All possible problems are still being checked.

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