1 Charged Z’s at Charged Z’s at Ruslan Chistov (ITEP, Moscow) Representing the Belle Collaboration Quarkonium Working Group Workshop (Nara, NWU, December 2-5/2008) ● Introduction ● Observation of Z(4430) + + ’ at Belle ● Observation of Z + 1,2 + c1 at Belle • Update of Z(4430) + at Belle (NEW) ● Summary D 0 D 1 * + c d c u
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1 Charged Z’s at Ruslan Chistov (ITEP, Moscow) Representing the Belle Collaboration Quarkonium Working Group Workshop (Nara, NWU, December 2-5/2008) ●
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Charged Z’s at Charged Z’s at
Ruslan Chistov (ITEP, Moscow)Representing
the Belle Collaboration
Quarkonium Working Group Workshop (Nara, NWU, December 2-5/2008)
● Introduction ● Observation of Z(4430)+ +’ at Belle ● Observation of Z+
1,2+c1 at Belle
• Update of Z(4430)+ at Belle (NEW)● Summary
D0D1*+c
d c
u
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L> 870 fb-1
High Luminosity has permitted usto obtain unexpected non-trivial results on charm spectroscopy, particularly with charmonium in the final state.
This has modified our understanding ofknown and predicted charmonia levels
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Observed and predicted Observed and predicted charmoniacharmonia
Described well the observed spectrum of cc states
A number of unexpected exotic states above DD(*) thresholds that do not fit into available cc slots
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The mechanisms of new The mechanisms of new particle production at B-particle production at B-
factoriesfactories
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 +-
Can charged Zbe in principle produced here?
Yes
yet unknown(e+e-
X+Y- ??)
No
No
Since onlyneutrals can be produced
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Observation of the Observation of the first manifestly first manifestly
exotic state exotic state Z(4430)Z(4430)++ at Belle at Belle
(2007)(2007)
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Z(4430)Z(4430)++ at at BelleBelle
PRL 100, 142001 (2008)
Study of BK+’:
’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
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Z(4430)Z(4430)++ at at BelleBelle
Total significance: 6.5 σM = (4433±41) MeV= (44+17
-13+30
-11) MeV Br(BKZ)xBr(Z(2S)+)=(4.1±1.0±1.3)·10-5
PRL 100, 142001 (2008)
Veto Veto
Fit: S-wave Breit-Wigner + Background with kinematic thresholds
Cross-checks:Z(4430)+ is present in both ’ subsamples
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Z(4430)Z(4430)++ at at BelleBelle
B+Z+Ks or B0Z-K+
Z±(2S)±
PRL 100, 142001 (2008)
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); …
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New charged Z’s decaying New charged Z’s decaying into into ++c1c1
Belle continued the study of other B(cc) +K- decays
PRD 78, 072004 (2008)
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Study of BK-+c1
Similar selection, then look at DP:
K*(892) K*(1430)
Horizontal band
Study it
B-signal
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Isobar Fit to entire Dalitz Isobar Fit to entire Dalitz Plot:Plot:
are the same order as are the same order as obtained for obtained for other, possiblyother, possiblyexotic X,Y,Z states.exotic X,Y,Z states.
No discrimination between J=0 or 1
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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
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New results on Z(4430)New results on Z(4430)++
Full Dalitz Plot analysis of BFull Dalitz Plot analysis of BKK--++’ ’
Data sample from original analysis is used
The same fitting technique as in BKc1 is used
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Dalitz Plot slices: Fit without a Z resonance:CL=0.1%
Introduce Z
A B C D E
No K*3(1780) in the fit model: A B
C D
E
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results on Z(4430)results on Z(4430)++ from Dalitz plot from Dalitz plot fitfit
The results of the DP fit in its slices with Z:
Confidence Level of the fit WITH Z(4430)+ is 36%
Signifi
cance
of Z
is 6
.4σ
NEWNEW
A B
C D
E
A B C D E
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Different fit models and the significance of Z(4430)+
Significance of Z(4430)+ in different fit models
is always larger than 5σ
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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
Updated parameters of Updated parameters of Z(4430)Z(4430)++
from Dalitz plot fitfrom Dalitz plot fit
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Summary of Belle results on Summary of Belle results on manifestly exotic states manifestly exotic states
• 2007: Belle observed first charged charmoniumlikestate, Z(4430)+ decaying into ’+
• 2008: Belle continued the study of BK(cc) decays and observed two new charged charmoniumlike statesZ(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.
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Back-up Back-up slidesslides
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K-+c1 Dalitz Plot Formalism
The decay BKc1 is described by 6 variables, M(c1), M(K), helicity angles c1, J/ and angles btw the production and decay planes c1, J/
Fitting function:
Amplitude for BKc1 via 2-bodyintermediate res.R and c1 in hel.
Angle dependent term:
Signal event density
Integrate over all angles; reconstruction efficiency is uniform over full angle ranges andinterference terms between different c1 helicity states are negligibly small.
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M(KM(K) description in B) description in BKK++’ ’ M(KM(K) description in B) description in BKK++c1c1
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M(KM(K) description in B) description in BKK++’ ’ Cross-Check: angular distributions Cross-Check: angular distributions
of the of the c1c1 and J/ and J/ in B in BKK++c1c1
Data and predictions from the default fit model agree very well and little discrimination between spin 0 and 1
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M(KM(K) description in B) description in BKK++’ ’
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Results of Dalitz Plot fit with two Results of Dalitz Plot fit with two Z’s in BZ’s in BKK++’ ’
Significance of two Z’s over one Z is 3.9σ
Preliminary
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Dalitz Plot efficiency in BDalitz Plot efficiency in BKK--