Recent BES Results on Charmonium Decays

Transcription

1 Recent BES Results on Charmonium Decays Changzheng YUAN IHEP, Beijing for the BES Collaboration XXXIVth Rencontres de Moriond QCD and Hadronic Interactions at High Energy Mar. 28 Apr. 4, 2004, La Thuile

2 BESII obtained 14 M ψ events MKI MKII MKIII CBAL BESI BESII CLEOc ψ V T ψ K 0 S K0 L (J/ ψ K 0 S K0 L ) ψ γγj/ψ χ cj ΛΛand pp ψ K 0 S K0 S

3 pqcd rule and ρπ puzzle pqcd rule (12% rule) [the relation between J/ ψ and ψ ] Q B B ψ' X ψ' + e e h = = = J/ψ X B + J/ψ e e B 12% Violation was revealed by MARK-II, confirmed by BES at higher sensitivity

4 ψ V T VT Mode BES-I results [PRL81(1998)5080] B(ψ X )(10 4 ) (PDG2002 from BES ) ω f 2 < 1.7 (C.L. 90 %) 1.1 ±0.5 ±0.2 [PRD67(2003)052002] B (J/ψ X )(10 3 ) (PDG2002) Q h ( % ) 4.3±0.6 < ±1.3 ρ a 2 < 2.3 (C.L. 90 %) 10.9±2.2 < 2.1 K * K * 2 < 1.2 (C.L. 90 %) 6.7±2.6 < 1.8 φ f ' 2 < 0.45 (C.L. 90 %) 1.23±0.21 < 3.7 This value from DM2 only 12 % rule ( pqcd rule ) Suppressed!!

5 ψ V T ψ ω f 2 π + π π 0 π + π ρ a 2 ρ π ππ ππ π + π π + π π 0 γγ π + π π + π π 0 γγ K * K * 2 Kπ Kπ K + K π + π φ KK f 2 ' KK K + K K + K

6 ψ V T Event Selection 1. Four charged tracks with net charge zero; 2. cosθ <0.80 for all tracks; 3. PartID using TOF+dE/dx 4. At least 2 photon candidates for π 0 channels; 5. Remove ψ(2s) π + π - J/ψ background; 6. Kinematic fit (4C/5C), Prob>0.01. χ 2 KF of ψ(2s) 5 π Data/MC

7 ψ V T B.G.( σ ) ω f 2 (1270) f 2 (1270) a 2 (1320) ρa 2 (1320) B.G.(M.C.) B.G.

8 ψ V T K * (892) Κ ( 892) 0 Κ 2(1430) (1525) φ f 2 K * 2 (1430) B.G. f 0 (980) f 2' (1525) B.G.

9 ψ V T B ψ' X = N ψ' n B obs ψ' X Y X Y ε MC VT mode B ψ X (10 4 ) (BES-II) ω f ± 0.41 ± 0.38 ρ a ± 0.73± 0.47 K * K * ± 0.32 ± 0.43 φ f 2 ' 0.44 ± 0.12 ± 0.11 This value from DM2 only Accepted by PRD B J/ψ X (10 3 ) (PDG2002) Q h (%) 4.3± ± ± ± ± ± ± ±1.5 Suppressed!! 12 % rule (pqcdrule )

10 ψ K S K L Theoretical Background pqcd rule & Phase Study B (ψ K S K L ) phase

11 The Relative Phase ψ K S K L J/ψ Decays: 1. AP: 90 M. Suzuki, PRD63, (2001) 2. VP: (106 ±10) J. Jousset et al., PRD41, 1389 (1990) D. Coffman et al., PRD38, 2695 (1988) N. N. Achasov, talk at Hadron PP: (90 ±10) M. Suzuki, PRD60, (1999) 4. VV: (138 ±37) L. Köpke and N. Wermes, Phys. Rep. 74, 67 (1989) 5. NN: (89 ±15) R. Baldini et al., PLB444, 111 (1998) ψ VP 1. φ=180 (90 ruled out!) M. Suzuki, PRD63, (2001) 2. φ= - 90 or φ=180 (with continuum amplitude) P. Wang, C. Z. Yuan and X. H. Mo, PRD69, (2004)

12 The Relative Phase ψ K S K L ψ Pseudoscalar Pseudoscalar A (π + π - )and A +B (K + K - )known, K S K L is needed to extract the phase between A and B. φ

13 ψ K S K L Event Selection π π + K L 1. Two Good charged tracks with net charge zero ; 2. Decay length in transverse plane greater than 1.0 cm for K S ID; 3. Total Energy of photon candidates less than 1 GeV.

14 Ks mass sidebands PRL 92, (2004) ψ K S K L Bkg MC 14M ψ(2s) signal

15 ψ K S K L BESII: First measurement for B(ψ K S K L ) B Quantity ψ' K S K L = n N obs ψ' /(ε f) B K S + ππ Value n obs 156 ± 14 ε MC (%) ± 0.48 f (%) 74.6 ± 3.5 N ψ (10 6 ) 14.0 ± 0.7 B Ks π+π ± B ψ Ks K L (10 5 ) 5.24 ± 0.47 ± 0.48 PRL 92, (2004)

16 ψ K S K L First measurement of the phase in ψ decays! K + K & π + π inputs ; Input 1:DASP; Input 2:BESI ; Input 3: K + K from BESI & π + π by form factor. B (ψ K S K L ) = PLB567 (2003)73 (82±29) (121±27)

17 J/ψ K S K L 58M J/ψ signal MC Bkg K* 0 K S +c.c. Ks mass sidebands PRD 69, (2004)

18 J/ψ K S K L BESII: Higher precision for B (J/ψ K S K L ) B J/ψ K S Quantity K L = n N PDG2002: B J/ψ Ks K L obs J/ψ /(ε f) B K S + ππ Value n obs 2155 ± 45 ε MC (%) ± 0.23 f (%) 77.2 ± 3.4 N ψ (10 6 ) 57.7 ± 2.7 B Ks π+π ± B J/ψ Ks K L (10 4 ) 1.82 ± 0.04 ± 0.13 = ( 1.08 ± 0.14 ) 10 4 ~4σ diff. PRD 69, (2004)

19 J/ψ, ψ K S K L B ψ Ks KL = (5.24± 0.47 ± 0.48 ) 10 5 B J/ ψ Ks KL = (1.82 ± 0.04 ± 0.13 ) 10 4 B B ψ' K J/ψ K K S L = (28.8 ± S K L 3.7)% Q B B ψ' X h = = J/ψ X 12% > 4σ B(ψ ) enhanced!

20 J/ψ, ψ K S K L A solution of ψ enhancement Wang, Mo and Yuan, hep-ph/ Prediction on ψ(3770) branching fraction: Searching for ψ(3770) K S K L to test the model! Wait for CLEOc/BESIII for the answer!

21 ψ γ γ J/ψ Measure 4 BRs: ψ π o J/ψ, ηj/ψ ψ γχ cj γγj/ψ (J=1,2) Different measurements deviate from each other B(ψ π o J/ψ) very crude (23 evts at CBAL, 7 evts at MRK2) Theoretical prediction for charmonium hadronic transition amplitude can be tested by the high statistics measurements Helicity amplitude analysis: not finished yet!

22 ψ γ γ J/ψ ηj/ψ γχ cj γγj/ψ BES Preliminary γγµµ BKG from π o π o J/ψ (MC) π o J/ψ J/ψ ee or µµ, 5C (J/ψ mass) kinematic fit is applied!

23 ψ γ γ J/ψ BES Preliminary π o J/ψ γχ cj γγee γγee γγµµ ηj/ψ γχ cj γγee γγµµ γγµµ

24 ψ γ γ J/ψ BES Preliminary

25 ψ γ γ J/ψ BES Preliminary γχ c1 ηj/ψ γχ c2 π o J/ψ BES BES measures the BRs in high precision!

26 ψ γ γ J/ψ Discussions BES Preliminary BES (+PDG for ϒ): R=0.048+/ R < R < PCAC [G. A. Miller, Phys. Rep. 194,1(1990)]: R= (too small!) QCD Multipole expansion & BTG potential model [Y. P. Kuang, PRD24, 2874(1981), ibid. 37, 1210(1988)] R = R =0.0013

27 COM for χ cj B B B(χ cj pp-bar) from BES, PRL81, 3091 (1998); E760, NPB373, 35 (1992); R704, PLBB172, 455 (1986) Nucleon wave function at small Q 2 : S. M. Wong, Eur. Phys. J. C14, 643 (2000) BES can measure them! J.Bolz, P. Kroll, Z. Phys. A356, 327 (1996) J.Bolz, P. Kroll, Eur. Phys. J. C2, 454 (1998) For each s quark, introduces

28 χ cj Λ Λ Event Selection Final states: γπ + π - pp-bar γ

29 χ cj Λ Λ Λ signal in πp mass Data Monte Carlo Clear ΛΛ-bar Signal

30 χ cj Λ Λ Fit the mass spectrum MC efficiencies χ c0 χ c1 χ c2 ΛΛ-bar Mass (GeV)

31 χ cj Λ Λ B χ cj Λ Λ = N ψ ' B n obs ψ' γχ /ε B cj 2 Λ π p Quantity χ c0 χ c1 χ c2 n obs ε(%) N ψ ± ± ± ± 0.24 B Λ π- p ± B ψ γχc J 8.7 ± ± ± 0.6 B χc J ΛΛ (10 4 ) ± ± ± PRD67, (2003)

32 cj p p Final states: γpp-bar χ c0 χ c1 χ c2 PRD, in press

33 cj p p PRD, in press

34 COM for χ cj B B Discussions 4 ( 10 ) c 0 B( χ cj ΛΛ) B( χ cj pp) (PDG02) 4.7 χ c ± χ χ c ± ± ± ± 0.74 ± B( χ cj pp) ± ± ± 0.10 COM predicts: for χ c1 and χ c2. Γ(χ cj ΛΛ-bar) ~½ Γ(χ cj p p-bar) B χ B( χ cj pp) BES results for ( ΛΛ) and cj do NOT agree with COM prediction No prediction for χ c0

35 Search for ψ, J/ψ K S K S CP violating process Test EPR paradox (Einstein-Podolsky-Rosen) MarkIII: 2.7M J/ψ B(J/ψ K S K S )< (@90% C.L.) BESII: 58M J/ψ 14M ψ Events selection 4 good charged tracks Q(sum) = 0 cosθ < 0.8 K S decay length Lxy > 3 mm M ππ -MK S > 2 σm

36 ψ, J/ψ K S K S 2 circles 1 σ & 2 σ regions from MC 1 evt in 2 σ region 1 evt in 2 σ region bkg= eff=21% bkg= eff=20% J/ψ K S K S candidate ψ K S K S candidate

37 ψ, J/ψ K S K S Upper Limits (@95% C.L.) 1st upper limit for B(ψ K S K S ). Higher sensitivity for B(J/ψ K S K S ) upper limit. Sensitivity insufficient for testing EPR paradox and CP violation. PLB (in press)

38 Summary ψ VT channels ω f 2, ρ a 2, K* K * 2 and φ f 2 ' are first observed and branching ratios are measured. The suppression of VT in ψ is confirmed. First observation of K 0 S K 0 L in ψ decay. Improved measurement of J/ψ K 0 S K 0 L. ψ is enhanced relative to the pqcd 12% rule. The phase for ψ PP is -82 or ψ γγj/ψ is studied to measure the BRs. Relative BR between Λ Λand p p in χ cj decays disagrees with COM+baryon wave function calculation. No K 0 S K 0 S signal observed in ψ and J/ ψ decays.

39 Thanks a lot! 谢谢!