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Recent BESII Results Representing BESII Collaboration Weiguo Li

Recent BESII Results Representing BESII Collaboration Weiguo Li Institute of High Energy Physics, Beijing 100049, P.R. China liwg@ihep.ac.cn Sino-German Workshop Frontiers in QCD DESY, Hamburg, Sep. 20, 2006. Outline Introduction Hadron Spectroscopy from J/ Decays

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Recent BESII Results Representing BESII Collaboration Weiguo Li

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  1. Recent BESII Results Representing BESII Collaboration Weiguo Li Institute of High Energy Physics, Beijing 100049, P.R. China liwg@ihep.ac.cn Sino-German Workshop Frontiers in QCD DESY, Hamburg, Sep. 20, 2006

  2. Outline • Introduction • Hadron Spectroscopy from J/ Decays • (2S) and CJ Physics • (3770) non DD Decays • Future Plan • Summary

  3. BESII Detector VC: xy = 100 m TOF: T = 180 ps counter: r= 3 cm MDC: xy = 250 m BSC: E/E= 22 % z = 5.5 cm dE/dx= 8.4 %  = 7.9 mr B field: 0.4 T p/p=1.8(1+p2) z = 2.3 cm Dead time/event: 〈10 ms

  4. Data from BESI and BESII BESII finished data taking April 2006

  5. Light Hadron Spectroscopy from J/ Decays • Scalars: ,  clearly observed • Possible pp bound state in J/  pp • X(1835) in J/  ’ • The  threshold enhancement in J/   • New observation of a broad 1- - resonance in J/  K+K- 0 • other topics

  6. The  pole in at BESII 0 M(+-0)  M()  M(+-)  Averaged pole position: MeV Phys. Lett. B 598 (2004) 149

  7. κ Phys. Lett. B 633 (2006) 681

  8. Phys. Rev. Lett. 91, 022001 (2003) Observation of an anomalous enhancement near the threshold of mass spectrum at BES II J/ygpp BES II 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 3-body phase space M(pp)-2mp (GeV) acceptance

  9. This narrow threshold enhancement is NOT observed in J/pp at BESII • This indicates X(1860) has a production property similar to ’ meson. • This also indicates X(1860) may have strong coupling to gluons as ’ meson. Preliminary J/ pp No narrow strong enhancement near threshold

  10. Not seen in pp experiment • In pp experiments, its expected cross-section is much smaller than continuum process • In pp elastic scattering, I=1 S-wave dominant, while in J/ radiative decays I=0 S-wave dominant. • Pure FSI disfavored not seen in: B+ K+ pp (BELLE) Y(1S) pp(CLEO)

  11. X(1835) 5.1  X(1835) 6.0  Observation of X(1835) in J/+-

  12. Combine two channels 7.7 Statistical Significance 7.7  X(1835) Phys. Rev. Lett., 95 (2005) 262001

  13. Re-fit to J/pp including FSI Include FSI curve from A.Sirbirtsev et al. ( Phys.Rev.D71:054010, 2005) in the fit (I=0) M = 1830.6  6.7 MeV  = < 153 MeV @90%C.L. In good agreement with X(1835)

  14. X(1860) and X(1835) might be the same state • masses and widths are consistent. • both connected with ’ meson.  Its spin-parity should be 0-+: this would be an important test. Excited ’ ? Glueball? pp bound state? A mixture of glueball and pp bound state?

  15. Observation of  thresholdenhancement in J/    M(K+K-)   M(K+K-) M(+-0) Dalitz plot   M2(g) M(+-0) M2(gw)

  16. A clear threshold enhancement is observed Phase Space Eff. curve Side-bands Side-bands do not have mass threshold enhancement!

  17. The decay of J/ is observed and an enhancement in  is found near the threshold. • PWA shows: the enhancement favors 0++ • Is it the same 0++ observed in KK or , or is it a • glueball, or a hybrid …..? • Further study in , K*K*,  …. desirable ! Phys. Rev. Lett., 96 (2006) 162002

  18. New observation of a broad 1- - resonance in J/  K+K- 0 K*(1410) 0 K*(892) 0 sideband background ? hep-ex/0606047, accepted by PRL

  19. What is the threshold bump? • JPC should be 1--, 3--, … (Parity conservation) • PWA results • Following components are neededK*(892), K*(1410), (1700), X • 1– is much better than 3— • Pole position of X is • Br • Big destructive interference among X, (1700) and PS

  20. More Checks • Replace X by (770), (1900), (2150) with interference among each other, S = 85 not from the interference of known particles • Replace X by (1450) S = 36 ( 8.2)& Br((1450) K+K-) < 1.6  10-3 (95% C.L.)  not (1450) • Further look in to determine its isospin • Search for its K*K, KK decay modes

  21. Property of X(1580) • The width is much broder than other mesons, such as (1450), (1700) Could have different nature from conventional mesons. • The large width is the expectation for a multiquark state(Tetraquark interpretation: M. Karliner, H.J. Lipkin, hep-ph/0607093)

  22. Observation of an enhancement near mass threshold in process M = (2075 12  5) MeV Γ = (90  35  9) MeV 7 stat. sig. BR = (5.9  1.4  2.0) 10-5 Phys. Rev. Lett. 93 (2004) 112002

  23. Near threshold enhancement in Nx (PS, eff. corrected) Nx suggesting a strong coupling to K Mass 1500~1650MeV Width70~110MeV JP favors 1/2- In the internal referee process

  24. BES II Preliminary   M(+-0)(GeV/c2) M(+-0)(GeV/c2) M(+-0)(GeV/c2) M(+-0)(GeV/c2)  sideband w signal with multiple entries w signal after best candidate selection (best w masses)

  25. M() M() Side-band Phase Space Eff. curve

  26. PWA analysis f0(1710) f0(1790) f0(1810) Total (1760) > 10  f0 6.5  (1760) f0(1710) Using observed mass and width for f0(1810) in J/y  g w f2(1640) 5.5  f2(1910) f2(160) f2(1910) 5.8  BG BG M() M() (GeV/c2)

  27. dominated by (1760) • a 0++ is possible needed (6.5 ) Accepted by PRD, hep-ex/0604045

  28. Study of the excited baryons

  29. The evidence of 2 new N* states in N*(1520) N*(1535) N*(1650) N*(1675) N*(1680) N*(1440)? ? PRL97, 062001 (2006)

  30. (2S) Decays • Transitions (~82%) • Hadronic transitions (~54%) • Radiative transitions (~28%) • Leptonic decays (~ 2%) • Hadronic decays (~15%) • Strong decays (~13%) • EM decays (~ 2%) • Radiative decays (~ 1%) • Rare decays and beyond SM (<<1%)

  31. (2S) leptonic decays: B(’+-) • First observation by DASP: ZPC1, 233(1979), no BR • First measurement by BESI: PRD65, 052004 (2002) • B=(0.271±0.043±0.055)% • Improvements: • Continuum contribution measured in data • Efficiency and background estimation • Interference subtraction more reasonable • Results: • 1015 events at resonance • 146 at continuum • B=(0.320±0.022±0.040)% • Lepton universality checked BES: preliminary

  32. (2S) and CJ Physics Continuum contribution and phase in (2S) decays Branching ratios Phase Interference needs to be considered. Continuum contribution should be subtracted … The interference are neglected in many of the current analyses.

  33. In analyzing (2S) decays, the continuum contribution should be subtracted and the phases between three glue and one photon process can be measured. With BESII 14 M (2S) events and 6.4 pb-1(s=3.65 GeV) and CLEOc 3 M events and 21 pb-1(s=3.67 GeV)12% rule are tested and the phases between three glue and one photon process for different processes are measured.

  34. The universal -90°phase? |φ| J/ψ Decays: 1. AP: 90°M. Suzuki, PRD63, 054021 (2001) 2. VP: (106 ±10)°J. Jousset et al., PRD41, 1389 (1990) D. Coffman et al., PRD38, 2695 (1988) N. N. Achasov, talk at Hadron2001 3. PP: (90 ±10)°M. Suzuki, PRD60, 051501 (1999) (103±7)°BES, PRD69, 012003 (2004) 4. VV: (138 ±37)°L. Köpke and N. Wermes, Phys. Rep. 174, 67 (1989) 5. NN: (89 ±15)°R. Baldini et al., PLB444, 111 (1998) ψ(2S) Decays: 1. VP: φ=180°(± 90 ° ruled out!)M. Suzuki, PRD63, 054021 (2001) φ=180° or φ=-90°P. Wang et al., PRD69, 057502 (2004) 2. PP: (-82±29)°or(121±27)° BES, PRL92, 052001 (2004) & Yuan, Wang, Mo, PLB567, 73 (2003)

  35. The “12% rule” M. Appelquist and H. D. Politzer, PRL34, 43 (1975) This is the famous (or notorious) “12% rule”.

  36. “12% rule”and“ puzzle” • Violation found by Mark-II , confirmed by BESI at higher sensitivity. • Extensively studied by BESII/CLEOc • VP mode:  , K*+K-+c.c., K*0K0+c.c., 0,… • PP mode: KSKL, K+K-, +- • BB mode: pp, , … • VT mode: K*K*2, f2’, a2, f2 • 3-body: pp0, pp, +-0, … • Multi-body: KSKShh, +-0 K+K- , 3(+-), … MARK-II K*K ρπ

  37. ’  PP BES, PRL 92, 052001 (2004) 156 evts Interference between ’ and continuum amplitudes in K+K- was not considered. CLEO, PRD74, 011105(R)(2006) Two possible phases: -80° or +121°. 4 evts 139 evts 53 evts

  38. J/, ’  PP: 12% rule BES, PRL 92, 052001 (2004) CLEO, PRD74, 011105(R)(2006) KK mode enhanced relative to the 12% rule. Pure EM mode  not enhanced, may be suppressed. J/  and ’ are related by ee of charmonia and  form factors.

  39. ’ + - 0 BESII: PLB619, 247 (2005) CLEOc: PRL94, 012005 (2005) 2290s 1960s BESII CLEOc BES and CLEOc in good agreement!

  40. ’ + - 0 Dalitz plots after applying 0 mass cut! Very different from J/3! CLEOc BESII J/ Similar Dalitz plots, different data handling techniques: PWA vs counting! ’ is observed, it is not completely missing, BR is at 10-5 level!

  41. J/, ’ VP BESII : PLB614, 37 (2005); PRD73, 052007 (2006) CLEOc : PRL94, 012005 (2005)

  42. Multi-body ’ decays BES: PRD71, 72006 (2005); PRD74, 12004 (2006) BESII, PRD73, 052004 (2006) CLEOc: PRD72, 051108 (2005) Some modes are suppressed, some are enhanced, while some others obey the 12% rule! CLEOc: PRL95, 062001 (2005)

  43. BES: preliminary ’ radiative decays • Total BR measured ~ 0.12% (total radiative decays ~1%)

  44. Mesonic decays BES: PRD73, 052004 (2006) PRD72, 012002 (2005) PLB630, 21 (2005) In agreement with 12% rule expectation

  45. Baryonic decays BES: PRD71, 072006 (2005) BES: preliminary Most modes in agreement with 12% rule expectation, also exceptions!

  46. Summary of “12%” rule, • ’ VP suppressed • ’ PP enhanced • ’ VT suppressed • ’ BB obey/enh • Multi-body obey/sup Seems no obvious rule to categorize the suppressed, the enhanced, and the normal decay modes of J/ and ’. The models developed for interpreting specific mode may hard to find solution for other (all) modes. Similarly ’’ decays have a rule of 0.02%, more data and more sophisticated analysis are needed to extract the branching fractions from the observed cross sections. Here because the time limitation, I will omit the results in this talk. • Model to explain J/, ’ and ’’ decays naturally and simultaneously? • S-D mixing in ’ and ’’[J. L. Rosner, PRD64, 094002 (2001)] • DD-bar reannihilation in ’’(J. L. Rosner, hep-ph/0405196) • Four-quark component in ’’[M. Voloshin, PRD71, 114003 (2005)] • Survival cc-bar in ’(P. Artoisenet et al., PLB628, 211 (2005)) • Other model(s)?

  47. ψ(2S) Decay is a cJ factory • ψ(2S)→cJ, J=0,1,2 • BJ~9%,“cJ factory” • observed in inclusive analysis • B(cJ→hadrons)are not • well known

  48. Pair production of vectors cJ c0 c1 c2 Improved precision over PDG (BESI) results on cJKKKK and . First measurement of cJKK. BES: cJ→2(K+K) hep-ex/0607025

  49. Pair production of vectors cJ 38 c0 28 c2 First observation: B(c0) = (2.290.580.41)10-3 B(c2) = (1.770.470.36)10-3 BES: PLB630, 7 (2005)

  50. c1 c2 cJh0h+h− BES: hep-ex/0607023 BES: PRD74, 012004 (2006)

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