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

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

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=2mD “open charm” threshold have been found Most of the above-threshold 1- - states & the cc2’ 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

y(4415) y(4150) y(4040) c’ c2 y” 2mD0

g Transitions M1 transitions (G(keV)) g e- E1 transitions J/y g hc 2.4 1.6 ± 0.4 y’ g hc 4.6 1.1 ± 0.2 Th. Expt pp,h,p0 g e- E1 transitions Th. Expt 24 27 ± 4 29 27 ± 3 26 27 ± 3 313 426 ± 51 239 291 ± 48 114 110 + 19

Hadronic transitions y’p0J/y y’ppJ/y Ispin violation: ~1/200 y’  J/y +hadrons Gexp(keV) y‘p+p- J/y 88 ± 7 y’ h J/y 9 ± 1 y’ p0J/y 0.4±0.1 pp, h, p0 pp,h,p0 g y’ J/y Ispin violation: y’p0J/y y’ppJ/y ~1/200

Predictions for the y” Gexp(keV) g g g e- y”p+p- J/y ~80 55 ± 15 th. Expt y”p+p- J/y ~80 55 ± 15 y” g cc1 77 70 ± 17 y” gcc0 213 172 ±30 g g pp,h,p0 g e-

Can we find other above-threshold states? y(4415) These 2 may be simpler y(4150) y(4040) c’ c2 hc2 yc2 y” 2mD0

yc2 (hc2)DD violates parity _ 2-+ & 2- -  DD not allowed hc2 yc2 Spin=0 c D J = 2 P=-1 D0 or D+ q yc2 c (or hc2) J = L P = (-1)L For J = 2 P = (-1)2 = +1 q c q D c D0 or D- Spin=0 yc2 (hc2)DD violates parity

Lowest possibility is DD* (or D*D) _ _ Lowest possibility is DD* (or D*D) Spin=0 c D J = 2 P=-1 D0 or D+ q c yc2 J = L + S P = (-1)L For J = 2, L=1 is OK P = (-1)1 = -1 q (or hc2) c q D* c D*0 or D*- Spin=1 yc2 (hc2)DD* doesn’t violate parity

yc2 & hc2 are expected to be below mD+mD* threshold

Belle: search for yc2 in BKyc2K(p+p-J/y) Eichten et al: PRL 98, 162002 (2002) c _ yc2 p+p- J/y?? B meson y’p+p-J/y s q _ K yc2??? M(p+p- J/y)-M(J/y) Belle PRL 91, 262001 (2003)

X(3872) MX=3872.0±0.6 MeV G<2.3 MeV Belle PRL 91, 262001 (2003)

X3872 is well established seen in 4 experiments CDF 9.4s 11.6s X(3872) D0 BaBar X(3872)

“Look for Xg cc1, you should Is the X(3872) the yc2? Bf(yc2g cc1) Bf(yc2p+p-J/y) Eichten et al: PRL 98, 162002 (2002) >5 “Look for Xg cc1, you should be flooded by events” Eichten

Belle search for X(3872)gcc1 Belle PRL 91, 262001 (2003) 3872 Bf(yc2g cc1) Bf(yc2p+p-J/y) <0.9 The X(3872) is not the yc2!!

If not yc2, what??? Agreement  Contradiction  Look for other decay modes: X(3872) g J/y ? X(3872) g y’? BaBar 2009: BaBar 2009: Yes Yes Agreement  Contradiction  PRL 102, 132001 Belle 2010: Belle 2010: Yes No V. Bhardwaj QWG 2010

C(X3872) = + C(X3872) must be (-)(-) = + X3872 g J/y if C(X3872) is + : p+p- system in X3872p+p- J/y must come from rp+p- p+ C = - r Belle agrees CDF agrees p- X3872 rp+p- lineshape J/y C = - M(p+p- ) M(p+p- )

JPC of X3872 0-+ ?? p+ r p- p* X3872 J/y mutually perpendicular m+ p+ 0-+ ?? spin polarization vectors p+ r p- p* X3872 J/y mutually perpendicular m+ p+ m- p-

Does the X(3872) JPC = 0-+ ?? 0-+ !!! No, the X(3872) cannot be 0-+

Does the X(3872) JPC = 1++ ?? B mutually perpendicular X(3872) K S=0 Sx=0

1++ fits well Belle Data

CDF angular correlation analysis Only 1++ or 2-+ fit data PRL 98 132002 1++ no adj. params 2- + 2 adj. 2arams 1- - O++ 1++ fits well with no adjustable parameters 2-+ looks like 1++ for , at least with current statistics

a 1++ cc state for the X3872? _ c’ c.f.: G(y’p0J/y)≈0.4 keV ‘ set by: Mcc2=3930 MeV ‘ Mass is too low? 3872 vs 3905 MeV G(cc1  g y’) ~180 keV G(cc1  g J/y) ~14 keV G(g y’)/G( g J/y)>>1 ‘ c’ ‘ c1 T.Barnes et al PRD 72, 054026 Gp+p- J/y =(3.4±1.2) GgJ/y~45 keV huge for Isospin-violating decay c.f.: G(y’p0J/y)≈0.4 keV

a 2-+ cc state for the X3872? _ hc2 BKhc2 violates factorization set by: My”=3770 MeV Mass is too high? 3872 vs 3837 MeV T.J. Burns et al arXiv:1008.0018 G(hc2  g y’) ~0.4 keV G(hc2  g J/y) ~9 keV G(hc2 g y’)/G(hc2 g J/y)<<1 Y. Jia et al arXiv:1007.4541 hc2 Gp+p- J/y =(3.4±1.2) GgJ/y ~30 keV huge for Ispin-violating decay c.f.: G(y’p0J/y)≈0.4 keV BKhc2 violates factorization BKhc not seen BKcc2 barely seen hc2  DD* expected to be tiny Belle & BaBar: G(XDD*)/G(XppJ/y)=9.5±3.1 Y. Kalasnakova et al arXiv:1008.2895

If not charmonium, what is it?

CDF X(3872)p+p- J/y Mass MX = 3871.61 ± 0.16 ± 0.19 MeV recent results ~6000 events! arXiv:0906.5218 MX = 3871.61 ± 0.16 ± 0.19 MeV

M X(3872) ≈ MD0 +MD*0 <MX>= 3871.46 ± 0.19 MeV new Belle meas. new CDF meas. MD0 + MD*0 3871.8±0.4 MeV dm = -0.35 ± 0.41 MeV

X(3872) looks like a D0D*0 “molecule” N. Tornqvist Z. Phys C 61, 525 (1994) predicted by Tornqvist in 1994, requires: JPC = 1++ or 0-+

States near 3940 MeV

Search for other states in BK p+p-p0 J/y decays _ J/y B meson wp+p-p0 s q _ K

M(w J/y) Y(3940) Y3940 p+p-p0J/y?? w M=3940 ± 11 MeV G= 92 ± 24 MeV unexpected peak at 3940 MeV Y3940 p+p-p0J/y?? Y(3940) w M=3940 ± 11 MeV G= 92 ± 24 MeV S.-K. Choi et al (Belle) PRL94, 182002 (2005)

Y(3940) confirmed by BaBar B±K±wJ/y B0KSwJ/y ratio M(wJ/y) PRL 101, 082001 Some discrepancy in M & G; general features agree

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

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

Study e+e-  J/y + anything detected J/y e+ e- J/y recoil system is undetected Recoil Mass:

s(e+e- J/y+cc) unexpectedly big _ Unexpected peak at 3940 MeV e+e- J/y+hc

Use “partial reconstruction” to study X3940 DD or DD* _ _ J/y e+ e- reconstruct these _ “Recoil” D(*) undetected (inferred from kinematics) _ _ _ D (or D*) D (or D*)

X(3940) DD* is large _ _ _ M = 3942 +7 ± 6 MeV -6 Gtot = 37 +26 ±12 MeV Nsig =52 +24 ± 11evts -6 -15 _ _ -16 e+e-  J/y + DD* arXiv:0708.3812 PRL 98, 802001 (2007) Bg subtracted

Use “partial reconstruction” to search for X(3940)wJ/y “Recoil” J/y undetected (inferred from kinematics) reconstruct these p J/y p p w3p 3940 MeV no signal:

X3940 & Y3940 are not the same from: from: e+e- J/y DD* & J/y wJ/y _ from: B K wJ/y & KDD* _

M(D*D*) has a peak too _ _ _ It has to have C=+; most likely 0-+ e+e-  J/y D* D* M = 4156 +25 ± 15 MeV Gtot = 139 +111 ± 21MeV Nsig =24 +12 ± 11evts -20 -61 -8 arXiv:0708.3812 _ It has to have C=+; most likely 0-+

cc assignments for X(3940), Y(3915) & X(4160)? _ hc’’’ 4160MeV hc” cc0’ 3940MeV 3915MeV Y(3915) = cco’? G(wJ/y) too large? X(3940) = hc”?  mass too low? X(4160) = hc”?  mass too high? X(4160) = hc”’?  mass much too low?

1- - states seen via “radiative return” “initial-state-radiation” photon: gISR kg 1- - E’ Ecm if kg = 3.8~4.5 GeV, E’ = 3~5GeV

Radiative return Ecm(GeV) B-factory energies g ss cc bb 3~5 GeV

e+e-  gisr Y(4260) at BaBar p+p- J/y BaBar PRL95, 142001 (2005) fitted values: 233 fb-1 M=4259  8 +2 MeV G = 88  23 +6 MeV -6 -9 Y(4260) ~50pb

“(4260) confirmed by Belle BaBar values: M=4247  12 +17 MeV -32 G = 108  19 ±10 MeV -32 M=4259  8 +2 MeV G = 88  23 +6 MeV -6 -9 M=4008  40 +114 MeV G = 226  44 ±87 MeV -28 ??? C.Z Yuan et al (Belle) PRL 99, 182004

Not seen in e+e-  hadrons J.Z.Bai et al (BES), PRL 88, 101802 (2006) s(e+e- hadrons) s(e+e-  m+m-) No sign of Y(4260)D(*)D(*) 4260 speak(Y(4260)+p-J/)~50 pb ~3nb Huge by charmonium standards BES data G(Y4260p+p- J/y) > 1.6MeV @ 90% CL X.H. Mo et al, PL B640, 182 (2006)

cc assignment for the Y(4260)?? only unfilled 1- - state left 33D1 4260MeV Y(4260) = 33D1?  mass too low & G(p+p-J/y) too large

another peak in e+e-  gISRp+p- y’ BaBar M=4324  24 MeV G = 172  33 MeV Peak is 4324 MeV, distinct from 4260 MeV

4325 MeV p+p-y’ peak in Belle Two peaks! (both relatively narrow) (& neither consistent with 4260) M=4361  9 ±9 MeV G = 74  15 ±10 MeV M=4664  11 ±5 MeV G = 48  15 ±3 MeV 4260 BaBar values M=4324  24 MeV G = 172  33 MeV X.L. Wang et al (Belle) PRL 99, 142002 (2007) 548 fb-1

At least three peaks for only one empty level 4664MeV 33D1 4361MeV 4260MeV

exclusive e+e- gISRD(*)D(*) channels

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

Experiment for BES III?: Search for other Y(4260) modes Scan the 4260 ± 100 MeV region & measure dominant channels to ± 1% DD* D*D* s  2nb 20 points  ~1 year of BES III data taking

The Z(4430)+  p+y’ “smoking gun” for a four quark meson? B0 K- B0

BK±p y’ (in Belle) ?? M2(p+y’) K*(1430)K+p-? K*(890)K+p- M2(K+p-)

The Z(4430)± p±y’ peak “K* Veto” Z(4430) BK p+y’ M2(p±y’) GeV2 M (Kp’) GeV Z(4430) M2(p±y’) GeV2 M(p±y’) GeV M2(Kp’) GeV2 “K* Veto”

Shows up in all data subsamples

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

Cos qp vs M2(py’) p qp +1.0 M2(py’) cosqp -1.0 K +1.0 22 GeV2 (4.43)2GeV2 0.25 M2(py’) cosqp 16 GeV2 -1.0 M (py’) & cosqp are tightly correlated; a peak in cosqp  peak in M(py’)

S- P- & D-waves cannot make a peak (+ nothing else) at cosqp≈0.25 not without introducing other, even more dramatic features at other cosqp (i.e., other Mpy’) values.

HW p qp y’ K Compute the relation between cosqp and M2(py’)

But…

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 ~1.9s from zero; fixing mass and width increases this to only ~3.1s.” Belle PRL: (4.1±1.0±1.4)x10-5

Reanalysis of Belle’s BKpy’ data using Dalitz Plot techniques

2-body isobar model for Kpy’ Our default model ky’ K*(890)y’ K*(1410)y’ K0*(1430)y’ K2*(1430)y’ K*(1680)y’ KZ+ K*y’ B K2*y’ Kpy’ KZ+

Results with no KZ+ term 2 1 1 2 3 4 5 C B A 3 4 A B 5 C fit CL=0.1% 51

Results with a KZ+ term 2 1 B 1 2 3 4 5 A 3 4 C B C A 5 fit CL=36%

Compare with PRL results K* veto applied With Z(4430) Signif: 6.4s Published results Without Z(4430) Mass & significance similar, width & errors are larger BaBar: Belle: = (3.2+1.8+9.6 )x10-5 0.9-1.6 No big contradiction

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

HW Devise strategies to determine JP of the Z(4430)+ p JP=0- JP=0- B K Spin=0 y’ JP=1- Are any JP values immediately ruled out? Can we use parity conservation? For which decays?

The Z1(4050)+ & Z2(4250)+ p+cc1 peaks R. Mizuk et al (Belle), PRD 78,072004 (2008)

Dalitz analysis of B0K-p+cc1 DE GeV ??? G K3*(1780) K*(890) K*(1680) K*(1400)’s M (J/yg) GeV

BKpcc1 Dalitz-plot analyses Default Model kcc1 K*(890)cc1 K*(1410)cc1 K0*(1430)cc1 K2*(1430)cc1 K*(1680)cc1 K3*(1780)cc1 KZ+ K*cc1 B K2*cc1 Kpcc1 KZ+

Fit model: all low-lying K*’s (no Z+ state) b c d g f e a b e f c d g C.L.=310-10

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

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

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

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

Systematics of B0 → K- π+ c1 fit M=1.04 GeV; G=0.26 GeV Significance of Z1(4050)+ and Z2(4250)+ is high. Fit assumes JZ1=0, JZ2=0; no signif. improvement for JZ1=1 &/or JZ2=1.

Z states cannot be charmonium d Need confirmation from other experiments (CDF? … D0?)

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

b-quark threshold region

Belle: G((4S)p+p-(1S)) 477 fb-1 2S 3S 4S (4S)  (1S) p+p- 52±10 evts N(4S) N(p+p-1S) B(Y4Spp1S) G(Y4Spp1S) Gtheory 535x106 52±10 9 ± 2 x10-5 1.75 ± 0.35 keV 1.47±0.03 keV

Belle: G(5Sp+p-1S) 1/20th the data & 1/10th the cross-section 23.6 fb-1 325±20 evts! 1/20th the data & 1/10th the cross-section >6 times as many events!! K.F. Chen et al (Belle) PRL 100, 112001 (2008)

Assuming the source is the (5S) Partial Widths Assuming the source is the (5S) PDG value taken for (nS) properties N.B. Resonance cross section 0.302 ± 0.015 nb at 10.87 GeV PRD 98, 052001 (2007) [Belle] >300 times bigger than that for the 4S!! c.f. (2S)  (1S) p+p- ~ 6 keV (3S) 0.9 keV (4S) 1.8 keV

Are these events from the 5S? s(e+e-  p+p-nS ) from a cm energy scan Fitted parameters 5S peak position PDG(5S): K.F. Chen et al (Belle) arXiv: 0810.3829

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

Y(4260) equivalent with s-quarks? e+e-  g f0(980)f Y(2175)f0(980)f s(e+e-  p+p- f(1020)) BaBar f0(980)p+p- M(f0(980)f) BaBar, PRD 74, 091103

Confirmed by BES & Belle confirmed by BESII in J/y  h f f0(980) s(e+e-  f0(980)f(1020)) BES Belle M(f0(980)f GeV C.P.Shen et al (Belle) arXiv: 0808.0006 M.Ablikim et al (BES) PRL 100, 102003 (2008)

The “XYZ” mesons

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 Ecm range We have to figure out how to access them (& find new ones) So far only final states with a J/y or y’ have been studied e.g., final states with an hc or a hc may be interesting Lots of opportunities for BES III Need creativity and new ideas

Thank You 謝謝 감사합니다