1 / 27

Resent BES Results on Scalar Mesons

Resent BES Results on Scalar Mesons. Zhipeng Zheng (Representing BES Collaboration) Institute of High Energy Physics, CAS GHP-2004, Oct. 25. OUTLINE. Introduction  and  f 0 (980) f 0 (1370) , f 0 (1500) , f 0 (1710) and f 0 (1790) Summary. Introduction (1).

gen
Download Presentation

Resent BES Results on Scalar Mesons

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Resent BES Results on Scalar Mesons Zhipeng Zheng (Representing BES Collaboration) Institute of High Energy Physics, CAS GHP-2004, Oct. 25

  2. OUTLINE • Introduction •  and  • f0(980) • f0(1370), f0(1500), f0(1710)and f0(1790) • Summary

  3. Introduction(1) Why are light scalar mesons interesting? • The knowledge on the light scalars is very important to the understanding of QCD in nonperturbative region • There have been hot debates on the existence of and  .

  4. Introduction(2) • f0(980): precise parameters m,  …. are needed. Is it a state, or molecular or four quark state? • Lattice QCD predicts the 0++ scalar glueball mass from 1.5 - 1.7 GeV. f0(1500) and f0(1710) are good candidates.

  5. Introduction(3) • f0(1370), f0(1500), f0(1710)were found in the fixed target, , e+e- experiments. The confirmation of them is important. • f0(1500), f0(1710) are treated as mixed state of glueball with meson, but we need more information. • The BESII data have much higher statistics and lead to a much more decisive partial wave analysis.

  6. Introduction(4) World J/ and (2S) Samples (×106) BESII Detector BESII 58MJ/ J/ BESII 14M(2S) • 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 (2S)

  7. The  pole in J/+-  0 M() M(+-0) f2(1270)   M(+-) f2(1270)

  8. Fit Method I: (whole mass region) Channels fitted to the data: J/f2(1270)  f0(980) b1(1235) ’(1450) f2(1565) f2(2240) b1(1235) f2 contribution f0 contribution

  9. Fit Method II: (M<1.5GeV) Fit to J/→+ (M < 1.5 GeV) f2 contribution f0 contribution Channels fitted to the data: J/f2(1270)  f0(980) b1(1235) P.S

  10. Breit-Wigner for  in the fit: (1) (2) (3) (4)

  11. Fit Result Method I Method II Averaged pole position: P. L. B 598 (2004) 149-158

  12.  in J/K+ - K+ - K1(1270), K1(1400) K*(892) K0*(1430), K2*(1430) ρ(770)

  13.  in J/K+ - K+ -  K*0(1430) K*

  14.  in

  15. f0(980) in J/+-,K+K- BESII preliminary • Important parameters from PWA fit: • Large coupling with KK indicates big component in f0(980) f0(980) f0(1370) f2(1525) f0(980)

  16. f0(1370) in J/+-, +- BESII preliminary • There has been some debate whether f0(1370) exists or not. • f0(1370) clearly seen in J/  , but not seen in J/  . f0(980) f0(1370) f2(1270) PWA 0++ components NO f0(1370)

  17. f0(1500) in J/+-, 00 BESII preliminary f2(1270) f0(1500) f0(1710) f0(1500) f2(1270) • One scalar with a mass = 1466  6  16 MeV is needed in J/  . • It’s also needed in the fit of J/  , kk • No peak directly seen in , KK, , KK channels. f0(1500)

  18. f0(1710) in PWA analysis shows one scalar. f2(1525) f0(1710) f2(1525) f0(1710) Phys. Rev. D 68 (2003) 052003

  19. f0(1710) in J/ f2(1270) • The scalar around 1710MeV with mass • Combine the branching ration of  and kk, we obtain: f0(1710) f2(1270) f0(1710) BESII preliminary

  20. f0(1710) in J/K+K-, +- • Clear f0(1710) peak in J/  KK. • No f0(1710) observed in J/   ! f0(1710) f2(1270) NO f0(1710) PWA 0++ components hep-ex/0409007

  21. f0(1790) in J/K+K-, +- BESII preliminary • 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(1710) ?

  22. Summary Summary of Scalar Meson at BES  Clear seen(peak + fit)  in the fit

  23. Summary • The existence of  is confirmed in J/+ - with pole position: • Evidence for the  as a peak close to threshold. Pole position:

  24. Summary • f0(980) is clearly seen in both +-, K+ K- data, parameters of f0(980)are well determined.

  25. Summary • f0(1370) is clearly seen in J/+- , But not evidence in J/+ - • f0(1500)is seen in J/ channel with mass: • f0(1710)is clearly seen in J/ KK with mass and width:

  26. Summary • f0(1710)is also seen in the J/, and K+K, but not seen in J/ +- • f0(1790) is needed in the fit of J/ +-, and need more study.

  27. Thank you!

More Related