Results from BES: cc Decays

Transcription

1 Results from BES: cc Decays Frederick A. Harris University of Hawaii Workshop on Quarkonium Nov. 8 10, 2002 at CERN

2 Introduction ψ(2s) Hadronic Results ψ(2s) Scan J/ψ Partial Wave Results J/ψ γp p-bar 2002 ψ(2s) Run BESIII Summary OUTLINE

3 The Beijing Electron Positron Collider L ~ ~ /cm 2 s at J/ψ peak E cm ~2-5 GeV A unique e + e - machine in the τ-charm energy region since 1989.

4 BESII Detector VC: σ xy = 100 µm TOF: σ T = 180 ps µ counter: σ rφ = 3 cm MDC: σ xy = 220 µm BSC: E/ E= 22 % σ z = 5.5 cm σ de/dx = 8.5 % σ φ = 7.9 mr B field: 0.4 T p/p=1.7 (1+p 2 ) σ z = 2.3 cm

5 Data Collected with BESI and BESII

6 World J/ψ and ψ(2s) Samples (10 6 ) J/ψ ψ(2s) MarkIII DM2 BESI BESII 0 MKI MKII MKIII CBAL BESI BESII

7 ψ(2s) Hadronic Decays Expectations: T. Applequist and D. Politzer, Phys. Rev. Lett. 51, 43 (1975).

8 Experimental Results BESI : 4 M ψ(2s)

9 ρπ Puzzle VP states like ρπ and K* K are strongly suppressed. First seen by MarkII with suppression factor ~20. BES finds suppression ~60. BES also finds suppression in VT channels

10 New channels with ω s and φ s Using 4 M BESI sample.

11 ψ( 2S) ωpp ψ( 2S) ωk + K ψ( 2S ) ωπ + π ψ(2s) b1π

12 ψ(2s) ωf2(1270) ψ(2s) φπ + π ψ(2s) φf0(980) ψ(2s) φk + K

13 Results - Preliminary Q = B(ψ(2S) h)/b(j/ψ h)

14 Submitted to Phys. Rev. D

15 ψ(2s) Scan ψ(2s) Scan Purpose: Improve accuracies of ψ(2s) parameters: Γ, Γ h, Γ µ, Γ ππ J/ψ, B(h), B(µ), and B(π + π - J/ψ). Ψ(2S) µ + µ - and Ψ(2S) π + π - J/ψ are important for identifying Ψ(2S) decays in B-factory and other experiments.

16 Scanned 24 energy points from 3.67 and 3.71 GeV. Integrated luminosity = 1150 nb -1 Four channels: ψ(2s) hadrons, µ + µ -, e + e -, and π + π - J/ψ For number of π + π - J/ψ, fit π + π - recoil mass spectrum.

17

18 Fitting Fit observed σ h (W), σ ππ J/ψ (W), σ e (W), and σ µ (W). Include resonance and continuum production plus interference, beam spread ( ), ISR and FSR. Assume Γ e = Γ µ = Γ τ /0.3885, Γ t = Γ h + Γ µ + Γ e + Γ τ. Determine Γ h, Γ µ, Γ ππ J/ψ, M(ψ(2S)),, and R. Results: R = 2.15 ± 0.17 consistent with BES R measurement (R = 2.25 ± 0.06 at 3.55 GeV). = ± Agrees with expected beam spread.

19 Fitting Result Parameter Γ t (kev) BES 264 ± 27(10.1 %) MARK I 228 ± 56 (24.6 %) PDG ± 25 (8.3 %) Γ h (kev) 258 ± 26(10.1 %) 224 ± 56 (25.0 %) Γ ππ J (kev) ψ Γ µ (kev) B h (%) ψ (%) (%) B ππ J B µ 85.4 ± 8.7 (10.1 %) 2.44 ± 0.21 (8.8 %) 97.8 ± 0.15 (0.16 %) 32.3 ± 1.4 (4.4 %) 0.93 ± 0.08 (8.5 %) 2.1 ± 0.3 (14.29 %) 98.1±0.3 (0.31 %) 32 ± 4 (12.5 %) 0.93 ±0.16(17.2 %) 2.19 ±0.15 (6.8 %) ±0.30 (0.31 %) 30.5 ± 1.6 ( 5.2 %) 0.7 ±0.09(12.9 %)

20 Discussion Width variation Γ t (kev) : (12%) Improved precision B h (%) : B ππ J/ψ (% ) : B µ (%) : First measurement of Γ ππ J/ψ Accepted by Phys. Lett.. B

21 J / ψ γkk PWA of, γπ + π at BES II (based on J/ψ) Results are preliminary!

22

23 PWA of J/ ψ γ K K and + γ 0 K S K 0 S J / ψ γkk the f 0 (1710) is a very important channel to investigate BESII preliminary 58M J / ψ 58M J / ψ

24 Global fit and bin-by-bin fit are performed BESII preliminary

25 Preliminary Results J / ψ ' Clear f 2 (1525) signal. Evidence of f 2 (1270). γkk ( ) 0 ++ is dominant in 1.7 GeV mass region Masses and widths (statistical errors only): f f ' 2 0 (1525) : M = 1518 ± MeV, Γ = 84 (1710) : M = MeV, Γ = MeV MeV

26 PWA of J /ψ γ π + π BESII Preliminary 58M J / ψ

27 BESII preliminary Preliminary Results ( J /ψ γπ + π) well known f 2 (1270) two 0 ++ s at around 1.4 and 1.7 GeV mass regions. for f 0 (1710): Γ( ππ) ~ 30% Γ(KK)

28 Observation of a resonance near p p-bar threshold in J/Ψ γ p p Based on 58 M J/ Ψ events. Preliminary. Event Selection 2 good charged tracks 1γ (isolated from charged tracks) Particle ID 4C-fits CL( γpp) > 0.05 CL( γpp) > CL( γk + K )

29 pp masses for selected events J / ψ γpp ( 58M J / ψ) Besides η c peak, there is a clear enhancement near threshold.

30 Backgrounds Main backgrounds from: 0 J / ψ π pp J /ψ γ p p No clear enhancement near threshold 0 J / ψ π pp (data)

31 Fit to the structure near threshold Background shape 0 from MC J / ψ π pp Preliminary results: (statistical error only) M = (1896 ± 2)MeV / c Γ = (57 ± 8)Mev / c Statistical significance: ~ 16σ 2 2

32 What is it? molecular state? pp + glueball? 0 why so close to? Dynamical effect? 2m p no evidence in or γλλ γξ + Ξ???? Searches for other decay modes

33 Year 2002 ψ(2s) run BES obtained 14 M ψ(2s) events. Now CLEOc will run at ψ(2s) ψ MARKI MarkII Crystal Ball BESI BES II

34 14M ψ(2s) (preliminary) ψ(2s) π + π J/ψ

35 IP BEPC Upgrade: BEPC II double ring RF SR RF e+ e -

36 BEPCII Beam energy 1 2 GeV Optimal energy 1.89 GeV Luminosity 1 x cm -2 s 1.89 GeV Linac requirements Dedicated SR Full energy injection: GeV Positron injection rate > 50 ma/min GeV Increase beam current; reduce beam size

37 BESIII Detector

38 Comparison Between BESIII and CLEOc Sub-system BES III σ XY (µm) = 130 CLEOc MDC EMC TOF µ counter P/P ( 0 / 0 ) = %(1 GeV) SC %(1 GeV) normal σ de/dx ( 0 / 0 ) = 6-7 % E/ E( 0 / 0 ) = 2.2%(1 GeV) σ z (cm) = cm/ E σ T (ps) = ps Barrel 110 ps endcap 9-10 layers 0.5 %(1 GeV) 6% 2.3 %(1 GeV) 0.5 cm / E RICH 3 layers magnet 1.0 tesla option tesla option tesla

39 Expected Event Rates at BES III 10 ψ, J/ψ &4.14 GeV Particle Energy Single Ring (1.2f -1 b ) Double Ring (4f b -1 ) D 0 ψ D + ψ Ds 4.14GeV τ + τ GeV 3.67GeV J/ψ ψ

40 Review on Feasibility& Design BEPC II feasibility international review (April 01, Beijing) BEPC II machine feasibility review ( July 01, Beijing) BESIII International Workshop (Oct. 01, Beijing) CAS review on BEPC II project (March 2002, Beijing ) International technical review of machine preliminary design (May, 02 SLAC) - China-US HEP cooperation item International technical review of preliminary detector design (Sept, 02 IHEP) Chair: M. Davier

41 Funding March 22: CAS review on the BEPCII proposal June: Chinese Government agreed to provide 540M RMB (65M US$) to BEPCII. The rest 100M RMB (12MUS$) will be the contribution from CAS and International collaboration. July 26: CAS submitted the proposal to the State planning Committee Sept. 4: State planning Committee review on the BEPCII proposal Key step: approval by the State Council meeting expected in weeks.

42 Summary Measured ψ(2s) decay modes containing ω s and φ s. These provide more information on 12 % Rule. Scan results improve on ψ(2s) resonance parameters. First measurement of Γ ππ J/ψ.. PWA of J/Ψ γk K-bar confirms that f(1710) is dominantly New narrow structure in J/ψ γp p-bar at threshold. What is it? New 14 M ψ(2s) will provide many new results.

43 Summary Future program: BEPCII/BESIII