Quarkonium Working Group Workshop Nara NWU December 2

Quarkonium Working Group Workshop (Nara, NWU, December 2 -5/2008) Charged Z’s at Ruslan Chistov (ITEP, Moscow) Representing the Belle Collaboration ● Introduction ● Observation of Z(4430)+ + ’ at Belle ● Observation of Z+1, 2 + c 1 at Belle • Update of Z(4430)+ at Belle (NEW) ● Summary c D 1* + d u D 0 c 1

L> 870 fb-1 High Luminosity has permitted us to obtain unexpected non-trivial results on charm spectroscopy, particularly with charmonium in the final state. This has modified our understanding of known and predicted charmonia levels 2

Observed and predicted charmonia A number of unexpected exotic states above DD(*) thresholds that do not fit into available cc slots Described well the observed spectrum of cc states 3

The mechanisms of new particle production at B-factories From B-decays, e. g. B+ X(3872)K+ In double charmonium production, e. g. e+e J/ψ X(3940) In fusion, e. g. c(2 S) or Z(3930) In radiative return, e. g. e+e- ISRY(4260) J/ψ + - Can charged Z be in principle produced here? Yes yet unknown (e+e- X+Y- ? ? ) No No Since only neutrals can be produced 4

Observation of the first manifestly exotic state + Z(4430) at Belle (2007) 5

Z(4430) + at Belle PRL 100, 142001 (2008) Study of B K + ’: ’ l+l- and J/ + (M( )>0. 44 Ge. V); B-candidates inv. mass is kinematically constrained to m. B (experim. resolution for M( ‘ +)~2. 5 Me. V); Horizontal band K*(1430) K*(892) Study it 6

+ Z(4430) Veto at Belle PRL 100, 142001 (2008) Veto Fit: S-wave Breit-Wigner + Background with kinematic thresholds Cross-checks: Z(4430) + is present in both ’ subsamples Total significance: 6. 5 σ M = (4433± 4 1) Me. V G= (44+17 -13+30 -11) Me. V Br(B KZ)x. Br(Z (2 S) +)= (4. 1± 1. 0± 1. 3)· 10 -5 7

Z(4430) + at Belle B+ Z+Ks or B 0 Z-K+ PRL 100, 142001 (2008) Z± (2 S)p± Charged, I=1 A variety of interpretations: - threshold effect (J. L. Rosner 0708. 3496, D. V. Bugg, 0709. 1254); - D*D 1 molecular state (X. Liu and Y. R. Liu, 0711. 0494); - radially excited tetraquark (L. Maiani, A. D. Polosa, V. Riquer, 0708. 3997); - baryonium state (C. F. Qiao, 0709. 4066 ); - hadro-charmonium (S. Dubinskiy, M. B. Voloshin, 0803. 2224); … Cannot be a conventional charmonium or hybrid state Should contain light quarks in addition to cc. 8

Belle continued the study of other B (cc) +K- decays New charged Z’s decaying + into PRD 78, 072004 (2008) c 1 9

Study of B K- + c 1 Similar selection, then look at DP: B-signal Horizontal band Study it K*(892) K*(1430) 10

Isobar Fit to entire Dalitz Plot: All known K*’s below 1900 Me. V + K*(892) + K*(1410) + K*0(1430) + K*2(1430) + K*(1680) + K*3(1780) + (Z’s) + Interference Efficiency over Dalitz Plot is included 11

The fit results in DP slices without any Z’s: A B C D D Confidence level of this fit: 3 x 10 -10 12

The fit results in DP slices A with one Z: A B C B D Confidence level of this fit: 0. 5% Try an additional Z 13

The fit results in DP slices with two Z’s: A A B C B D Confidence level of this fit: 42% 14

Parameters of the new EXOTIC Z+1, 2 + c 1 states and Mass( + c 1) distribution No discrimination between J=0 or 1 are the same order as obtained for other, possibly exotic X, Y, Z states. 15

Systematics and significances (incl. d. o. f. ) from various fit models: The worst case, but theparam’s of this new K* are far from those for all known K*’s 16

Full Dalitz Plot analysis of B K- + ’ Data sample from original analysis is used The same fitting technique as in B K c 1 is used New results on Z(4430) + 17

Dalitz Plot slices: Fit without a Z resonance: CL=0. 1% No K*3(1780) in the fit model: A B C D E E Introduce Z 18

NEW results on Z(4430) + from Dalitz plot fit A B C D E The results of the DP fit in its slices with Z: Confidence Level of the fit WITH Z(4430)+ is 36% a c i f i gn. 4σ i S 6 is e c n Z f o 19

Different fit models and the significance of Z(4430)+ Significance of Z(4430)+ in different fit models is always larger than 5σ 20

Updated parameters of Z(4430) + from Dalitz plot fit Sum of 3 slices (K*’s veto) Pr eli mi na ry Belle confirms the original result on Z(4430)+ Width is larger than original but uncertainties are large 21

Summary of Belle results on manifestly exotic states • 2007: Belle observed first charged charmoniumlike state, Z(4430)+ decaying into ’ + • 2008: Belle continued the study of B K (cc) decays and observed two new charged charmoniumlike states Z(4050)+ and Z(4250)+, decaying into + c 1 • Update on Z(4430)+: Dalitz Plot analysis confirms original observation. The Z(4430)+ has a significance of 6. 4σ. These states have similar character: have non-zero electric charge and decay into ordinary charmonia and +. The current options for their nature include tetraquark, molecular type states and hadro-charmonium. 22

Back-up slides 23

K- + c 1 Dalitz Plot Formalism The decay B K c 1 is described by 6 variables, M( c 1), M(K ), helicity angles c 1, J/ and angles btw the production and decay planes c 1, J/ Integrate over all angles; reconstruction Fitting function: efficiency is uniform over full angle ranges and interference terms between different c 1 helicity states are negligibly small. Amplitude for B K c 1 via 2 -body intermediate res. R and c 1 in hel. Angle dependent term: Signal event density 24

M(K ) description in B K + c 1 M(K ) description in B K + ’ 25

Cross-Check: angular distributions of the c 1 and J/ M(K ) description in Bin K B+ ’K + c 1 Data and predictions from the default fit model agree very well and little discrimination between spin 0 and 1 26

M(K ) description in B K + ’ 27

Results of. Dalitz. Plot fit with two Z’s in B K + ’ Significance of two Z’s over one Z is 3. 9σ Preliminary 28

Dalitz. Plot efficiency in BK- + c 1 29