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Radiative Decays and Searches for Glueballs

Radiative Decays and 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. Outline. PWA of , at BES II

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Radiative Decays and Searches for Glueballs

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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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