e + e - physics in the tau charm energy region Part I Frederick A. Harris University of Hawaii Jan. 5, 2005

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1 e + e - physics in the tau charm energy region Part I Frederick A. Harris University of Hawaii Jan. 5, 2005

2 OUTLINE Introduction Oldies but goodies τ mass measurement and R scan ψ(2s) scan and radiative and hadronic transitions: ψ(2s) γγj/ψ, XJ/ψ 12% Rule and ρπ puzzle ψ(2s) VT and VP η C parameters Summary

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

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: ΔE/ E= 22 % σ z = 5.5 cm σ de/dx = 8.5 % σ φ = 7.9 mr B field: 0.4 T Δp/p=1.7 (1+p 2 ) σ z = 2.3 cm

5 CLEO-c New comer to tau charm energy region. Ran at ψ" in 2003 with 6 wigglers (~60 pb -1 ). Running now with all 12. Luminosity ~0.6 x pb -1 s -1 Luminosity expected ~2 x pb -1 s pb -1 at ψ" this year? Have well understood, state of the art detector.

6 Charmonium spectrum below open charm ψ(3770) Charm threshold n 2S+1 L J

7 World J/ψ and ψ(2s) Samples ( 10 6 ) J/ψ ψ(2s) 58 M 14 M MarkIII DM2 BESI BESII 0 MKI MKII MKIII CBAL BESI BESII CLEO

8 Oldies but goodies

9 Tau mass measurement Use e + + e - τ + τ - e e, e μ, e h, μ μ, μ h, and h h events (+ 4 ν s). h = π or K Use PID plus cuts on kinematic variables. Fit threshold excitation over 12 scan points 5 pb -1 of data.

10 BES measurement: Tau mass measurement m τ = MeV/c 10X better precision J. Z. Bai et al, PRD53, 20 (1996).

11 Tau mass measurement Leptonic decay rate in SM: 2 5 GL ml Γ( L lν Lν l ) = F 3 cor 192π ( m L, m l ) (Fcor ~ 1) For muon decay, m μ, t μ, and F cor are used to determine G F 1 Γ( μ eν μ ν e ) = t For tau: Γ ( τ eν τ ν ) e = B τ eνν Γτ = τ eνν Lifetime, leptonic branching ratio, and mass related. Was poorly satisfied before BES measurement. μ B t τ

12 Tau mass measurement Lifetime, leptonic branching ratio, and mass: 1992 Status 2000 Status 1992 (2.4 σ) A. Pich, hep-ph and 1994 (1.3 σ)

13 Tau mass measurement Test lepton universality: Value should be ~1 if universality holds. G ( G τ eνν μ eνν ) 2 = ± With new m τ G ( G τ eνν μ eνν ) 2 = ± Tests universality at ½% level. using PDG2004 Novosibirsk planning a new tau mass measurement.

14 R Measurement R provides strong evidence for the quark model and 3 colors. For u, d, s R 2 For u, d, s, c R 3 1/3 For u, d, s, c, b R 3 2/3 PDG2000 Selected measurements

15 R Measurement Improved R values are very important: Needed for interpretation of a μ = (g 2)/2. Much of the theoretical uncertainty from R - but mostly from E CM < 2 GeV region. 1.9 σ 0.7 σ M. Davier et al., Eur. Phys. J. C31, 503 (2003).

16 R measurement Needed to improve precision of α(m 2 Z): Uncertainties in α introduced when it is extrapolated to the Z-pole: Dominant uncertainty due to hadronic vacuum polarization. This is determined from R values using a dispersion relation.

17 R measurement The Higgs mass determined from radiative corrections in the SM is very sensitive to α(m 2 Z). B. Pietrzyk and H. Burkhardt (1997).

18 BES R Measurement Determination of R: Runs ~1000 events per energy point

19 BES R-scan Results published: J.Z. Bai et.al., Phys. Rev. Lett. 84, 594 (2000). J.Z. Bai et.al., Phys. Rev. Lett. 88, (2002) citations so far; tau mass paper - 67

20 BES R Measurement BES R Measurement BES Results (continued).

21 R Below 10 GeV BES reduces R errors from % to an average of 6% in the 2 5 GeV region. Important region! Before BES R Scan After BES R Scan

22 Current Status Burkhardt and Pietryzk have updated analysis [Phys. Lett. B513, 46 (2001).] Data driven approach: data for E < 12 GeV Error about half previous error. Shifts Standard Model Higgs mass upward.

23 The SM Fit to m H Without BES data With BES data m m H H = GeV < 170 GeV m GeV (95% C.L.) m < 212 GeV H H = (95% C.L.)

24 The Latest SM Fit to m H Thanks to B. Pietrzyk Without BES data With BES data m m H H = GeV < 170 GeV m + = GeV (95% C.L.) m < 260 GeV H H 45 (95% C.L.) In 2004 with new top mass

25 ψ(2s) scan and radiative and hadronic transitions

26 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. 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

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28 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 (Δ), 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)), Δ, and R. Results: R = 2.15 ± 0.17 consistent with BES R measurement (R = 2.25 ± 0.06 at 3.55 GeV). Δ = ± MeV. Agrees with expected beam spread.

29 Fitting Result Parameter BES MARK I PDG2002 Γ t Γ h Γ ππ J Γ μ B h B ππ J (kev) (kev) B μ ψ (kev) (kev) (%) (%) ψ (%) Phys. Lett.. B550, 24 (2002) 264 ± 27(10.1 %) 228 ± 56 (24.6 %) 300 ± 25 (8.3 %) 258 ± 26(10.1 %) 224 ± 56 (25.0 %) 85.4 ± 8.7 (10.1 %) 2.44 ± 0.21 (8.8 %) 2.1 ± 0.3 (14.29 %) 2.19 ±0.15 (6.8 %) 97.8 ± 0.15 (0.16 %) 98.1±0.3 (0.31 %) ±0.30 (0.31 %) 32.3 ± 1.4 (4.4 %) 32 ± 4 (12.5 %) 30.5 ± 1.6 ( 5.2 %) 0.93 ± 0.08 (8.5 %) 0.93 ±0.16(17.2 %) 0.7 ±0.09(12.9 %)

30 ψ' γ γ J/ψ Measure: ψ' π o J/ψ, ηj/ψ ψ' γχ cj γγj/ψ (J=1,2) Old measurements disagree. B(ψ π o J/ψ) very crude: (23 evts at CBAL, 7 evts at MRK2). Theoretical predictions for charmonium hadronic transition amplitudes can be tested by high statistics measurements.

31 ψ' γ γ J/ψ ηj/ψ γχ cj γγj/ψ BKG from π o π o J/ψ π o J/ψ J/ψ ee or μμ, 5C (J/ψ mass) kinematic fit is applied!

32 ψ' γ γ J/ψ ψ(2s) π o J/ψ ψ (2S) γχ cj γγj/ψ γγee γγee γγμμ ψ(2s) ηj/ψ ψ (2S) γχ cj γγj/ψ γγee γγμμ γγμμ

33 ψ' γ γ J/ψ PDG ± ± 0.08

34 ψ' γ γ J/ψ γχ c1 BES most accurate ηj/ψ γχ c2 π o J/ψ BES BES measures the BRs with high precision! Phys.Rev.D70:012006,2004

35 ψ' γ γ J/ψ BES (+PDG for ϒ): R= ± 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" =

36 ψ' X J/ψ B(ψ(2S) hadrons)/b(j/ψ hadrons) = B(ψ(2S) ggg + ggγ)/b(j/ψ ggg + ggγ) = 0.23 ± 0.07 Disagrees with 12 % Rule Important to measure ψ X J/ψ and components. M. Suzuki, PRD63, , (2001). Y. F. Gu and X. H. Li, PRD63, (2001). Method identify J/ψ μ + μ - Select muons. 1 C fit to m J/ψ determine m X p X p μ+ pj/ψ p μ-

37 ψ' X J/ψ Inclusive measurement use events that satisfy 1 C fit. J/ψ peak Fit distribution: background (m μμ < 3.4) 1307 events signal events Background e + e - γμ + μ - and e + e - ψ γμ+ μ-

38 ψ' X J/ψ Exclusive measurements To separate ψ π 0 π 0 J/ψ and π 0 π 0 J/ψ, plot m X for no extra charged tracks and for extra charged tracks. Fit two simultaneously with component shapes. χ 2 < 7 no extra ππ extra ππ η backgrd χ c2 χ c1 η

39 ψ' X J/ψ Determine ratio of branching ratios to B(ψ π + π - J/ψ ) to cancel systematic errors. Constrain χ C2 /χ c1 since shapes similar. Results measured Phys.Rev.D70:012003,2004 BESI 4 million ψ(2s) events.

40 CLEOc results on ψ(2s) transitions and radiative decays From talk by Brian Heltsley at the Third Quarkonium Working Group Meeting, Beijing, Oct , ( Measure inclusive and exclusive. 3.1 M (± 3 %) ψ(2s) decays Fully reconstruct events J/ψ μμ, ee η γγ, π + π - π 0 Preliminary

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42 CLEOc ψ(2s) inclusive gamma spectrum ψ (2S) γ χ cj ( Good calorimeter allows measurement of inclusive spectrum. ψ (2S) γ χ cj Can determine B( ). Higher than PDG? Yes.

43 12% Rule and ρπ Puzzle

44 12% Rule and ρπ puzzle strong electromagnetic non-resonant pqcd 12% rule : ψ(2s) signal continuum T. Appelquist & H.D. Politzer, PRL 34 (1975) 43 A. De Rujula & S.L. Glashow, PRL 34 (1975) 46 J/Ψ and Ψ hadronic decays proceed via 3 gluons or a virtual photon. cc annihilation decay rate ~ ψ(0) 2 B B ψ' X ψ' e + e Q h = = = 12% B J/ ψ X B J/ ψ e + e Complications: α S corrections Relativistic corrections Interference with continuum (See talk by C.Z. Yuan at 2 nd QWG meeting) Etc. ( Take as Rule of thumb

45 12% Rule and ρπ puzzle ρπ puzzle: Suppression in VP mode (ρπ & K*K ) revealed by MARK-II { M.E.B. Franklin et al, PRL 51 (1983) 963 } Q(ρπ) < 0.6% Q(K*K) < 2 % Suppression confirmed by BESI with higher sensitivity Suppression in VT mode found by BESI { J. Z. Bai et al, PRL 81 (1998) 5080 } Q(ωf 2 ) < 4.0%, Q(ρa 2 )< 2.1%, Q(K * K * 2) < 1.8%, Q(φf 2 ) < 3.7%

46 12% Rule and ρπ puzzle Theoretical explanations: Brodsky, Lepage, Tuan: {PRL 59 (1987) 621 } Intermediate vector glueball Chaichian & Torngvist : {NP B323 (1989) 75 } Hadronic form factor Pinsky : {PL B236 (1990) 479 } Generalized hindered M1 transition Li-Bugg-Zou {PR D55 (1997) 1421 } Final-state interaction Brodsky-Karliner {PRL 78 (1997) 4 Intrinsic charm qqcc> Fock components of the light vector mesons Chen-Braaten {PRL 80 (1998) 5060 } Fock state with cc pair in a color-octet Gerard-Weyers {PL B462 (1999) 324 } cc annihilation into 5g via 2 steps Feldmann-Kroll {PR D62 (2000) } Decays thru light-quark Fock component by a soft mechanism Suzuki {PR D63 (2001) } ψ(2s) - vector glueball mixing Rosner {PR D64 (2001) } ψ(2s) - ψ(1d) mixing J. P. Ma {PR D65 (2002) } Relativistic Correction Many ruled out. Still interesting: ψ(2s) - ψ(1d) mixing.

47 Ψ(2S) V T Ψ(2S) 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 K + K f 2 ' KK K + K K + K

48 Ψ(2S) V T 14 million ψ(2s) events BESII B.G.( σ ) f 2 (1270) a 2 (1320) B.G.(M.C.) First observation (1270) ω f 2 ρa 2 (1320)

49 Ψ(2S) V T BESII K * (892) K * 2 (1430) f 0 (980) f 2' (1525) B.G. Κ 0 ( 892) Κ (1430) 2 + c. c. First observations φ f (1525) 2

50 Ψ(2S) V T VT mode B ψ ( 2 S ) X B ψ(2s) X (10 4 ) (BES-II) 2.05± 0.41 ± ω f ρ a ± 0.73± 0.60 K * K * 1.64± 0.33 ± φ f ' 0.48 ± 0.14 ± This value from DM2 only 12 % rule ( pqcd rule ) = N n ψ ( 2 S ) obs ψ ( 2 S ) X Y B X Y B J/ψ X (10 3 ) (PDG2002) ε MC Q h (%) 4.3± ± ± ± ±0.06±0.20 Phys.Rev.D69:072001,2004 BESII 2.3± ± ±1.6 Suppressed!!

51 ρπ VP Mode Dalitz plot for J/Ψ and Ψ(2S) 3π are very different J/ Ψ 3π Ψ(2S) 3π PRD70 (2004) BESII Preliminary

52 ρπ VP Mode BESII Preliminary ( PWA ) Mππ in Ψ(2S) 3π ρ(770), ρ(2150) -- dominant

53 ρπ Results on BRs BR BESII (10 5 ) PDG04 (10 5 ) Ψ(2S) π + π - π ± 1.8 ± ± 5 Ψ(2S) ρπ 5.1 ± 0.7 ± 0.8 < 8.3 Ψ(2S) VP Mode ρ(2150) π π + π - π ± BESII Preliminary ( PWA ) Should help the understanding of the ρπ puzzle. hep-ex/ submitted to PRL

54 VP Mode ψ (2S) K*(892)K + c.c. K S Kπ K S π + π - K* ± K *0

55 VP Mode K*(892)K Ψ(2S) K *± (892) K + Ψ(2S) K *0 (892) K 0 K *0 K* ± 9.6±4.2 Evts. 65.6±9.0 Evts. M ( K 0 m π ) M ( K ± m π ) Br ± (2.9±1.3±0.4) 10 5 Br 0 (15.0±2.1±1.9) 10 5 = 5.2±2.7 Large isospin-violation hep-ex/ , submitted to PRL

56 Results of VP mode ψ Nevt B(ψ ) ( 10-5 ) B(J/ψ) ( 10-4 ) Q (%) PDG04 ρ (770) π 5.1 ± 0.7 ± ± ±0.08 ρ (2150) π 19.4 ± 2.5 Upper C.L * Preliminary ρη 13.2 ± ± 0.65 ± ± ± 3.7 ρη 2.5 ± ± 1.27 ± ± ± 12.9 ωπ 14.0 ± ± 0.64 ± ± ± 1.8 ωη <3.3 < ± 1.6 < 0.7 ωη 4.1 ± ± 2.9 ± ± ± 19 ϕπ < 3.0 < 0.3 < ϕη 17.8 ± ± 1.0 ± ± ± 1.9 ϕη 9.1 ± ± 1.3 ± ± ± 4.5 K + K* - +c.c. 9.6 ± ± 1.3 ± ± ± 0.27 K 0 K* 0 +c.c ± ± 2.1 ± ± ± 0.8

57 Test of pqcd 12% Rule Results BESII Preliminary 12% Rule to naive

58 Test of pqcd 12% Rule Even more BES BESII preliminary

59 Talk by Brain Heltsley at Third Quarkonium Workshop, Oct ( ) ~3 million ψ(2s) events continuum data: pb -1 (BES 6.42 pb -1 ) CLEOc subtracts continuum without considering interference. For ρπ, no PWA. Just use ρ(770) peak. Neglect interference. CLEOc Results

60 CLEOc Results

61 BESII vs. CLEO (ψ BRsResults) Most channels BRs are consistent. BESII Preliminary Upper C.L. BES BR(ρπ) > CLEO by ~ 3σ, because PWA takes into acount the interference. BR(K* 0 K 0 ) are deviated CLEO BRs calculated from hep-ex/

62 12% Rule and ρπ puzzle There are many new measurements from BES and CLEOC. Agreement is good, especially if differences in continuum subtraction taken into consideration. These should help to explain the ρπ puzzle.

63 η c parameters

64 η c Parameters Precise (m J ψ -m ηc ) needed for potential models. But η c mass not well determined: PDG02 CL = 0.001

65 Width Measurements Values spread all over with large errors.

66 η C measurements with BESII 58 M J/ψ sample J/ψ γ η C, η C pp M(pp)

67 J/ψ γη C, η C K + K - π + π - J/ψ γη C, η C π + π - π + π - M(K + K - π + π - ) M(π + π - π + π - ) J/ψ γη C, η C K K S π J/ψ γη C, η C φφ M(φφ) M(K +/- K 0 S π-/+ )

68 Results: Mass and Width Combined fit of five channels: M(η C ) = ± 1.0 ± 1.2 MeV/c 2 Γ(η C ) = 17.0 ± 3.7 ± 7.4 MeV/c 2 PDG M(η C ) = ± 1.5 MeV Γ(η C ) = MeV Phys. Lett.. B555, 174 (2003)

69 BES2003 Results: Mass and Width Results: Mass and Width BaBar BaBar PDG2004 BaBar Γ = 34.3 ± 2.3 ± 0.9 MeV/c 2 γγ production 88 fb -1 of data hep-ex/ , Phys. Rev. Lett. 92: (2004).

70 Results: Branching Fractions Product Branching Fractions Systematic Errors

71 Results: Branching Fractions Dividing by B(J/ψ γη c ) = 1.3 ± 0.4 % (PDG2002) * * H.C. Huang et al., hep-ex/ * Calculated from results in F. Fang, et al., PRL 90:071801,2003. B(η c φφ) is smaller than PDG and agrees with Belle measurement (hep-ex/ ). Physics Letter B578, 16 (2003).

72 Summary BES has Made fundamental measurements of the τ mass and R in the 2-5 GeV energy region. Important for testing lepton universality and the SM. Improved ψ(2s) parameters from a ψ(2s) scan and measurements of radiative and hadronic transitions. ψ(2s) π 0 J/ψ, η J/ψ, π 0 π 0 J/ψ, γχ cj, and anything J/ψ. Measurements for BRs of ψ(2s) VP channels: ψ(2s) (ρ,ω,ϕ)(π,η,η ), K*K o In ψ(2s) 3π, ρ(770) & ρ(2150) dominant. o Large isospin-violation in ψ(2s) KK* channel. o Results agree well with CLEOc. Measured η C mass, width, and branching ratios.

73 Thanks