Charmonium experimental overview

Transcript

1 Charmonium experimental overview Stephen Lars Olsen Seoul National University Topical Seminar on Frontier of Particle Physics Hu Yu Village, Beijing CHINA August 27-28, 2010

2 outline Lecture1: History & the discovery of the bound charmonium states Yesterday Lecture 2: The non-charmonium, charmonium-like states & the future Today

3 Summary (lecture 1) The charmonium spectrum is strong evidence that hadrons are composed of spin=1/2 constituent particles All of the charmonium states below the M=2m D open charm threshold have been found Most of the above-threshold 1 -- states & the χ c2 have been identified The masses of the assigned states match theory predictions -variations are less than ~50 MeV Transitions between charmonium states are in reasonably good agreement with theoretical expectations

4 ψ(4415) ψ(4040) χ c2 ψ(4150) ψ 2m D 0

5 γ Transitions M1 transitions (Γ(keV)) Th. Expt J/ψ γ η c ± 0.4 ψ γ η c ± 0.2 ππ,η,π 0 γ e - E1 transitions Th. Expt ± ± ± ± ±

6 Hadronic transitions ππ,η,π 0 γ ψ J/ψ +hadrons Γ exp (kev) ψ π + π J/ψ 88 ± 7 ψ η J/ψ 9 ± 1 ψ π 0 J/ψ 0.4±0.1 ππ, η, π 0 ψ J/ψ Ispin violation: ψ π 0 J/ψ ψ ππj/ψ ~1/200

7 Predictions for the ψ γ γ Γ exp (kev) th. Expt ψ π + π J/ψ ~80 55 ± 15 ψ γχ c ± 17 ψ γχ c ±30 ππ,η,π 0 γ e -

8 Can we find other abovethreshold states? ψ(4415) ψ(4040) χ c2 η c2 ψ(4150) ψ ψ c2 These 2 may be simpler 2m D 0

9 _ 2 -+ & 2 -- DD not allowed η c2 ψ c2 J = 2 P=-1 c q Spin=0 D 0 or D + D ψ c2 (or η c2 ) c c q J = L P = (-1) L For J = 2 P = (-1) 2 = +1 q c D Spin=0 D 0 or D - ψ c2 (η c2 ) DD violates parity

10 Lowest possibility is DD* (or D*D) J = 2 P=-1 c q Spin=0 D 0 or D + D ψ c2 (or η c2 ) c c q J = L + S P = (-1) L For J = 2, L=1 is OK P = (-1) 1 = -1 q c D* Spin=1 D* 0 or D* - ψ c2 (η c2 ) DD* doesn t violate parity

11 ψ c2 & η c2 are expected to be below m D +m D* threshold ψ(4415) ψ(4040) χ c2 ψ(4150) η c2 ψ c2 ψ m D + m D* 2m D

12 Belle: search for ψ c2 in B Kψ c2 K(π + π - J/ψ) Eichten et al: PRL 98, (2002) c_ c ψ c2 π + π - J/ψ?? B meson ψ π + π - J/ψ s_ q K ψ c2??? M(π + π - J/ψ)-M(J/ψ) Belle PRL 91, (2003)

13 X(3872) M X =3872.0±0.6 MeV Γ<2.3 MeV Belle PRL 91, (2003)

14 X 3872 is well established seen in 4 experiments 9.4σ 11.6σ CDF X(3872) D0 BaBar X(3872)

15 Is the X(3872) the ψ c2? Eichten et al: PRL 98, (2002) Bf(ψ c2 γχ c1 ) Bf(ψ c2 π + π - J/ψ) >5 Look for X γ χ c1, you should be flooded by events Eichten

16 Belle search for X(3872) γχ c Belle PRL 91, (2003) Bf(ψ c2 γχ c1 ) Bf(ψ c2 π + π - J/ψ) <0.9 The X(3872) is not the ψ c2!!

17 If not ψ c2, what??? Look for other decay modes: X(3872) γ J/ψ? BaBar 2009: PRL 102, Belle 2010: Yes Agreement Yes X(3872) γ ψ? BaBar 2009: Belle 2010: Contradiction Yes No V. Bhardwaj QWG 2010

18 C(X 3872 )= + X 3872 γ J/ψ C = - C = - C(X 3872 ) must be (-) (-) = + if C(X 3872 ) is + : π + π - system in X 3872 π + π - J/ψ must come from ρ π + π - X 3872 C = - ρ π + π Belle agrees ρ π + π - lineshape CDF agrees C = - J/ψ M(π + π - ) M(π + π - )

19 0 -+?? p* ε r ρ ρ π + π L int J PC of X 3872 spin polarization vectors r r ( ε ) ρ ε p * J / ψ r J/ψ r X ε 3872 J /ψ p r * ε r ρ r ε J / ψ mutually perpendicular d dγ cosϑ μ sin 2 ϑ μ ϑr μ μ + d dγ cosϑ π 2 cos ϑ π ϑ π π + μ - ε J /ψ π - ε r ρ

20 Does the X(3872) J PC = 0 -+?? dγ 2 2 sin ψ sin ϑ d cosψd cosϑ 0 -+ r ε J /ψ p r * ε r ρ!!! No, the X(3872) cannot be 0 -+

21 Does the X(3872) J PC = 1 ++?? L int r r ( ) ε ε ε ρ J ψ X / r r ε X ε r ρ r ε J / ψ mutually perpendicular x K S=0 B X(3872) S x =0 ε r X ε J / ψ ε r r ρ

22 1 ++ fits well r ε J /ψ dγ sin dcosχd cosϑ μ 2 χsin 2 ϑ μ Belle Data ε r X ε r ρ

23 CDF angular correlation analysis Only 1 ++ or 2 -+ fit data PRL no adj. params adj. 2arams 1 -- O fits well with no adjustable parameters 2 -+ looks like 1 ++ o i for, at least with current statistics α 0.6e 20

24 _ a 1 ++ cc state for the X 3872? set by: Mχ c2 =3930 MeV Mass is too low? 3872 vs 3905 MeV χ c1 Γ(χ c1 γψ ) ~180 kev Γ(χ c1 γ J/ψ) ~14 kev T.Barnes et al PRD 72, Γ(γ ψ )/Γ( γ J/ψ)>>1 Γ π+π J/ψ =(3.4±1.2) Γ γj/ψ ~45 kev huge for Isospin-violating deca c.f.: Γ(ψ π 0 J/ψ) 0.4 kev

25 _ a 2 -+ cc state for the X 3872? set by: Mψ =3770 MeV Mass is too high? 3872 vs 3837 MeV T.J. Burns et al arxiv: η c2 Γ(η c2 γψ ) ~0.4 kev Γ(η c2 γ J/ψ) ~9 kev Y. Jia et al arxiv: Γ(η c2 γψ )/Γ(η c2 γ J/ψ)<<1 Γ π+π J/ψ =(3.4±1.2) Γ γj/ψ ~30 kev huge for Ispin-violating decay c.f.: Γ(ψ π 0 J/ψ) 0.4 kev B Kη c2 violates factorization B Kh c not seen B Kχ c2 barely seen η c2 DD* expected to be tiny Y. Kalasnakova et al arxiv: Belle & BaBar: Γ(X DD )/Γ(X ππj/ψ)=9.5±3.1

26 If not charmonium, what is it?

27 CDF X(3872) π + π J/ψ Mass recent results ~6000 events! arxiv: M X = ± 0.16 ± 0.19 MeV

28 M X(3872) M D 0 +M D* 0 <M X >= ± 0.19 MeV new Belle meas. new CDF meas. M D0 + M D* ±0.4 MeV δm = ± 0.41 MeV

29 X(3872) looks like a D 0 D* 0 molecule N. Tornqvist Z. Phys C 61, 525 (1994) predicted by Tornqvist in 1994, requires: J PC = 1 ++ or 0 -+

30 States near 3940 MeV

31 Search for other states in B K π + π - π 0 J/ψ decays B meson c_ c π + π 0 π J/ψ s_ q K ω π + π π 0

32 M(ω J/ψ) unexpected peak at 3940 MeV Y(3940) Y 3940 π + π π 0 J/ψ?? ω M=3940 ± 11 MeV Γ= 92 ± 24 MeV S.-K. Choi et al (Belle) PRL94, (2005)

33 Y(3940) confirmed by BaBar B ± K ± ωj/ψ B 0 K S ωj/ψ Μ(ωJ/ψ) ratio PRL 101, Some discrepancy in M & Γ; general features agree

34 Belle-BaBar direct comparison 492fb -1 Same binning (Belle published result : 253 fb -1 ) Belle will update with the complete ϒ(4S) date set later this Fall

35 Does Y(3940) DD*? _ B KDD* _ 3940 MeV 3940 MeV No signal:

36 Study e + e - J/ψ + anything detected J/ψ J/ψ recoil system is undetected e + e - Recoil Mass: M 2 recoil = ( E cm E J / ψ ) ( p J / ψ ) r 2

37 _ σ(e + e - J/ψ+cc) unexpectedly big Unexpected peak at 3940 MeV e + e - J/ψ+η c

38 Use partial reconstruction to study X 3940 DD or DD* J/ψ reconstruct these e + e - _ D (or D*) _ D (or D*) _ Recoil D ( * ) undetected _ (inferred from kinematics) M D (*) 2 2 = ( Ecm EJ / ψ E (*) ) ( pj / + p (*) ) D ψ D r r

39 _ X(3940) DD* is large 3940 MeV _ e + e - J/ψ + DD* M = ± 6 MeV Γ tot = ±12 MeV _ Nsig = ± -16 arxiv: PRL 98, (2007) Bg subtracted

40 Use partial reconstruction to search for X(3940) ωj/ψ J/ψ reconstruct these e + e - π π π ω 3π 3940 MeV J/ψ no signal: Recoil J/ψ undetected (inferred from kinematics)

41 X 3940 & Y 3940 are not the same from: _ e + e - J/ψ DD* & J/ψ ωj/ψ from: B K ωj/ψ & _ KDD*

42 _ M(D*D*) has a peak too _ e + e - J/ψ D* D* _ M = ± 15 MeV -20 Γ tot = ± -61 Nsig = arxiv: ± 11evts It has to have C=+; most likely 0 -+

43 _ cc assignments for X(3940), Y(3915) & X(4160)? η c 3940MeV η c χ c0 4160MeV 3915MeV Y(3915) = χ co? Γ(ωJ/ψ) too large? X(3940) = η c? mass too low? X(4160) = η c? mass too high? X(4160) = η c? mass much too low?

44 1 -- states seen via radiative return initial-state-radiation photon: γ ISR k γ E cm E 1 -- if k γ = 3.8~4.5 GeV, E = 3~5GeV

45 Radiative return γ B-factory energies ss cc bb GeV 3~5 GeV E cm (GeV)

46 e + e - γ isr Y(4260) at BaBar π + π - J/ψ BaBar PRL95, (2005) 233 fb -1 fitted values: M=4259 ± 8 +2 MeV Γ = 88 ± MeV Y(4260) ~50pb

47 (4260) confirmed by Belle M=4247 ± MeV -32 Γ = 108 ± 19 ±10 MeV BaBar values: M=4259 ± 8 +2 MeV Γ = 88 ± MeV M=4008 ± MeV -28 Γ = 226 ± 44 ±87 MeV??? C.Z Yuan et al (Belle) PRL 99,

48 Not seen in e + e - hadrons J.Z.Bai et al (BES), PRL 88, (2006) σ(e+e- hadrons) σ(e+e- μ+μ-) 4260 No sign of Y(4260) D ( * ) D ( * ) σ peak (Y(4260) π + π J/ψ) 50 pb ~3nb BES data Huge by charmonium standards Γ(Y 4260 π + π J/ψ) > 90% CL X.H. Mo et al, PL B640, 182 (2006)

49 cc assignment for the Y(4260)?? only unfilled state left 3 3 D MeV Y(4260) = 3 3 D 1? mass too low & Γ(π + π J/ψ) too large

50 another peak in e + e - γ ISR π + π - ψ e + e - γ ISR π + π - ψ 2 Events / 50MeV/c 10 BaBar Data Y(4260) + BKG New resonance + BKG BKG (non-ψ(2s)) M=4324 ± 24 MeV Γ = 172 ± 33 MeV m(2(π + π )J/ψ) (GeV/c ) Peak is 4324 MeV, distinct from 4260 MeV

51 4325 MeV π + π ψ peak in Belle Two peaks! (both relatively narrow) (& neither consistent with 4260) M=4361 ± 9 ±9 MeV Γ = 74 ± 15 ±10 MeV 4260 M=4664 ± 11 ±5 MeV Γ = 48 ± 15 ±3 MeV BaBar values M=4324 ± 24 MeV Γ = 172 ± 33 MeV X.L. Wang et al (Belle) PRL 99, (2007) 548 fb -1

52 At least three peaks for only one empty level 4664MeV 4260MeV 3 3 D MeV

53 exclusive e + e - γ ISR D ( * ) D ( * ) channels

54 DD DD * D * D * DD π Sum of all exclusive contributions DD * π Λ + c Λ c Phi to Psi 2009 Only small room for unaccounted contributions Charm strange final states Limited inclusive data above 4.5 GeV Galina Pakhlova Charm baryons final states

55 Experiment for BES III?: Search for other Y(4260) modes Scan the 4260 ± 100 MeV region & measure dominant channels to ± 1% DD * D * D * σ 2nb 4 Nevts 10 1 dtlum = = 50 pb / 3 s effic 2 10 pb points ~1 year of BES III data taking pt

56 The Z(4430) + π + ψ smoking gun for a four quark meson? ψ B 0 Z +? Ḵ B 0

57 B K ± π m ψ (in Belle)?? M 2 (π + ψ ) K*(1430) K + π -? K*(890) K + π - M 2 (K + π - )

58 The Z(4430) ± π ± ψ peak B K π + ψ M(Κπ ) GeV Z(4430) M(π ± ψ ) GeV M 2 (π ± ψ ) GeV 2 M 2 (Κπ ) GeV 2 K* Veto

59 Shows up in all data subsamples

60 Could the Z + (4430) be due to a reflection from the Kπ channel?

61 Cos θ π vs M 2 (πψ ) θ π π ψ K 22 GeV (4.43) 2 GeV cosθ π M 2 (πψ ) 16 GeV M (πψ ) & cosθ π are tightly correlated; a peak in cosθ π peak in M(πψ )

62 S- P- & D-waves cannot make a peak (+ nothing else) at cosθ π 0.25 not without introducing other, even more dramatic features at other cosθ π (i.e., other M πψ ) values.

63 HW θ π π ψ K Compute the relation between cosθ π and M 2 (πψ )

64 But

65 BaBar doesn t see a significant Z(4430) + For the fit equivalent to the Belle analysis we obtain mass & width values that are consistent with theirs, but only ~1.9σ from zero; fixing mass and width increases this to only ~3.1σ. Belle PRL: (4.1±1.0±1.4)x10-5

66 Reanalysis of Belle s B Kπψ data using Dalitz Plot techniques

67 2-body isobar model for Kπψ Our default model K*ψ κψ Β K 2 *ψ Kπψ K*(890)ψ K*(1410)ψ K 0 *(1430)ψ KZ + K 2 *(1430)ψ K*(1680)ψ KZ +

68 Results with no KZ + term C B 3 4 A A B 5 fit CL=0.1% C 51

69 Results with a KZ + term C A B B C 5 A fit CL=36%

70 Compare with PRL results K* veto applied With Z(4430) Signif: 6.4σ Published results Without Z(4430) Mass & significance similar, width & errors are larger BaBar: Belle: = ( )x No big contradiction

71 Variations of the model Z(4430) + significance Others: Blatt f-f term 0 r=1.6fm 4fm; Z + spin J=0 J=1; incl K* in the bkg fcn

72 HW Devise strategies to determine J P of the Z(4430) + π J P =0 - J P =?? Z + B Spin=0 J P =0 - Κ ψ J P =1 - Are any J P values immediately ruled out? Can we use parity conservation? For which decays?

73 The Z 1 (4050) + & Z 2 (4250) + π + χ c1 peaks R. Mizuk et al (Belle), PRD 78, (2008)

74 Dalitz analysis of B 0 K - π + χ c1 ΔE GeV Γ K*(890) K*(1400) s K*(1680) K3 *(1780) M(J/ψγ) GeV???

75 B Kπχ c1 Dalitz-plot analyses Default Model Β K*χ c1 K 2 *χ c1 Kπχ c1 κχ c1 K*(890)χ c1 K*(1410)χ c1 KZ + K 0 *(1430)χ c1 K 2 *(1430)χ c1 K*(1680)χ c1 K 3 *(1780)χ c1 KZ +

76 Fit model: all low-lying K* s (no Z + state) a b c d g f e a b e f c d g C.L.=

77 Fit model: all K* s + one Z + state a b c d g f e a b e f c d g C.L.=0.1%

78 Are there two????? a b c d

79 Fit model: all K* s + two Z + states a b c d g f e a b e f c d g C.L.=42%

80 Two Z-states give best fit Projection with K* veto

81 Systematics of B 0 K - π + χ c1 fit M=1.04 GeV; G=0.26 GeV Significance of Z 1 (4050) + and Z 2 (4250) + is high. Fit assumes J Z1 =0, J Z2 =0; no signif. improvement for J Z1 =1 &/or J Z2 =1.

82 Z states cannot be charmonium u c c ud Need confirmation from other experiments (CDF? D0?)

83 Are there XYZ counterparts in the b- and s-quark sectors? What about here? 233 fb -1 Y(4260)

84 b-quark threshold region

85 Belle: Γ(ϒ(4S) π + π - ϒ(1S)) 477 fb -1 ϒ(4S) ϒ(1S) π + π 2S 3S 52±10 4S N(ϒ 4S ) N(π + π - ϒ 1S ) B(Y 4S ππϒ 1S ) Γ(Y 4S ππϒ 1S ) Γ theory 535x ±10 9 ± 2 x ± 0.35 kev 1.47±0.03 kev

86 Belle: Γ(ϒ 5S π + π ϒ 1S ) 2 Entries / GeV/c fb (a) μμππ candidates in Υ(1S) μ μ region 325±20 evts! ΔM = M(μμππ)-M(μμ) (GeV/c ) 1/20 th the data & 1/10 th the cross-section >6 times as many events!! K.F. Chen et al (Belle) PRL 100, (2008)

87 Partial Widths Assuming the source is the ϒ(5S) PDG value taken for ϒ(nS) properties N.B. Resonance cross section ± nb at GeV PRD 98, (2007) [Belle] >300 times bigger than that for the ϒ 4S!! c.f. ϒ(2S) ϒ(1S)π + π ϒ(3S) ϒ(4S) ~ 6 kev 0.9 kev 1.8 kev

88 Are these events from the ϒ 5S? σ(e+e- π + π ϒ ns ) from a cm energy scan ϒ 5S peak position K.F. Chen et al (Belle) arxiv: PDG(ϒ 5S ): Fitted parameters

89 Peak & width in π + π - ϒ(nS) different from ϒ(5S) &ϒ(6S) Simplest interpretation: b-quark-sector equivalent to the c-quark-sector s Y(4260) e + e - π + π Y(nS) e + e - hadrons

90 Y(4260) equivalent with s-quarks? e+e- γ f 0 (980)φ σ(e + e - π + π φ(1020)) Y(2175) f 0 (980)φ BaBar f 0 (980) π + π - M(f 0 (980)φ) BaBar, PRD 74,

91 Confirmed by BES & Belle confirmed by BESII in J/ψ η φ f 0 (980) σ(e + e - f 0 (980)φ(1020)) BES Belle M(f 0 (980)φ GeV C.P.Shen et al (Belle) arxiv: M.Ablikim et al (BES) PRL 100, (2008)

92 The XYZ mesons

93 Concluding remarks Charmonium mesons are strong evidence for quarks All the lowest-lying charmonium states have been found Good agreement between their measured properties & theory Charmonium is the best understood hadronic system Higher-mass charmonium meson searches have produced surprizes A number of non-charmonium meson candidates have been found. They have strong transitions to ordinary charmonium states Corresponding states sem to exist in the b-qyark & s-quark sectors Most of the new states are in the BEPC-II E cm range We have to figure out how to access them (& find new ones) So far only final states with a J/ψ or ψ have been studied e.g., final states with an η c or a h c may be interesting Lots of opportunities for BES III Need creativity and new ideas

94 Thank You 감사합니다