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Charged Z’s at

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

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Charged Z’s at

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  1. Charged Z’s at D1*+ D0 c u  d c Quarkonium Working Group Workshop (Nara, NWU, December 2-5/2008) Ruslan Chistov (ITEP, Moscow) Representing the Belle Collaboration ● Introduction ● Observation of Z(4430)+ +’ at Belle ● Observation of Z+1,2+c1 at Belle • Update of Z(4430)+ at Belle (NEW) ● Summary

  2. 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

  3. 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

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

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

  6. Z(4430)+ at Belle PRL 100, 142001 (2008) Study of BK+’: ’l+l- and J/+- (M()>0.44 GeV); B-candidates inv. mass is kinematically constrained to mB (experim. resolution for M(‘+)~2.5 MeV); Horizontal band K*(1430) K*(892) Study it

  7. Z(4430)+ at Belle PRL 100, 142001 (2008) Veto Veto • Total significance: 6.5 σ • M = (4433±41) MeV • = (44+17-13+30-11) MeV Br(BKZ)xBr(Z(2S)+)= (4.1±1.0±1.3)·10-5 Fit: S-wave Breit-Wigner + Background with kinematic thresholds Cross-checks: Z(4430)+ is present in both ’ subsamples

  8. Z(4430)+ at Belle PRL 100, 142001 (2008) B+Z+Ks or B0Z-K+ Z±y(2S)p± Charged, I=1 Cannot be a conventional charmonium or hybrid state Should contain light quarks in addition to cc. A variety of interpretations: - threshold effect (J.L.Rosner 0708.3496, D.V.Bugg, 0709.1254); - D*D1 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); …

  9. New charged Z’s decaying into +c1 Belle continued the study of other B(cc) +K-decays PRD 78, 072004 (2008)

  10. Study of BK-+c1 Similar selection, then look at DP: B-signal Horizontal band Study it K*(892) K*(1430)

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

  12. The fit results in DP slices without any Z’s: A B A B C D C D Confidence level of this fit: 3x10-10

  13. The fit results in DP slices with one Z: A B A B C D C D Confidence level of this fit: 0.5% Try an additional Z

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

  15. Parameters of the new EXOTIC Z+1,2 +c1 states and Mass(+c1)distribution No discrimination between J=0 or 1 are the same order as obtained for other, possibly exotic X,Y,Z states.

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

  17. New results on Z(4430)+ Full Dalitz Plot analysis of BK-+’ Data sample from original analysis is used The same fitting technique as in BKc1 is used

  18. Dalitz Plot slices: Fit without a Z resonance: CL=0.1% A B C D E No K*3(1780) in the fit model: A B C D E Introduce Z

  19. NEW results on Z(4430)+ from Dalitz plot fit A B C D E 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% Significance of Z is 6.4σ

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

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

  22. 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 +c1 • 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.

  23. Back-up slides

  24. K-+c1 Dalitz Plot Formalism The decay BKc1 is described by 6 variables, M(c1), M(K), helicity angles c1, J/ and angles btw the production and decay planes  c1, J/ Integrate over all angles; reconstruction efficiency is uniform over full angle ranges and interference terms between different c1helicity states are negligibly small. Fitting function: Amplitude for BKc1 via 2-body intermediate res.R and c1 in hel. Angle dependent term: Signal event density

  25. M(K) description in BK+c1 M(K) description in BK+’

  26. Cross-Check: angular distributions of the c1 and J/ in BK+c1 M(K) description in BK+’ Data and predictions from the default fit model agree very well and little discrimination between spin 0 and 1

  27. M(K) description in BK+’

  28. Results of Dalitz Plot fit with two Z’s in BK+’ Significance oftwo Z’s over one Z is 3.9σ Preliminary

  29. Dalitz Plot efficiency in BK-+c1

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