Bled Workshops in Physics Vol. 10, No. 1 p. 88
Proceedings of the Mini-Workshop Problems in Multi-Quark States Bled, Slovenia, June 29 - July 6, 2009

Hadronic spectroscopy at Belle*
M. Brackoa,b and T. Zivkob, representing the Belle Collaboration
a University of Maribor, Smetanova ulica 17, SI-2000 Maribor, Slovenia b JoZef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
Abstract. The Belle experiment continues with study of Dsj particles, as well as charmo-nium and charmonium-like states. Recent results on these topics are briefly mentioned.
Belle is an experiment at the e+ e- collider KEKB [1]. The main goal of the experiment is a precision measurement of CP violation in the system of B mesons. The asymmetric KEKB collider operates around the center-of-mass energy of the Y(4S) resonance; the total collected integrated luminosity is about 945 fb-1 in July 2009. The large amount of data and excellent detector performances enable successful study of other topics besides properties of B mesons. In what follows, news from Belle about charmed strange mesons, charmonium and charmonium-like states will be briefly mentioned. Details of the reported analyses can be found in quoted references.
New charmed strange meson, Dsj (2700) +, was observed in the decay channel D°K+ [2]. Angular analysis favours spin-parity assignment 1-. It is possible that this particle is X(2690), which was previously observed by BABAR [3].
Partial wave analysis of another charmed strange meson, Ds1 (2536) +, in decay channel D*+K° revealed domination of the S wave [4], at variance with HQET prediction.
Properties of charmonium-like state, X(3872), were further studied. Positive charge parity is established [5], while favoured JP is 1 + or 2-. Belle updated the analysis of the X(3872) in the D0Ddecay channel [6]. The measured mass value is compatible with the new BABAR measurement [7]. According to all measurements, the favoured interpretation is that the X(3872) is a mixture of the D°D molecule and a cc state.
A new state, named Z+(4430) and decaying to ^(2S)n+, is observed in the B meson decays to Kn±^(2S) final state [8]. An updated measurement, based on a full Dalitz plot analysis of the Kn±^(2S) final state, was performed recently [9]. Results of this analysis confirm the original discovery of the Z+ (4430).
Two new states, Z+ (4050) and Z+ (4250), decaying to Xci were observed in K~Xci decays of B° [10]. All three observed charged charmonium-like states - Z+ (4430), Z+ (4050) and Z+ (4250) - are serious tetraquark candidates.
* Talk delivered by T. Zivko
New particles, X(3940) and X(4160), decaying to D* ID and D* ID * were observed in events with double cc production [11], The established experimental technique was used to measure the cross section for e+ e- —> J/^cc in a model independent way [12].
Several new Y states and peaks in mass plots were observed in initial state radiation events [13]. These states are regarded as serious charmonium - gluon hybrid candidates [14].
As new experimental data are still accumulated and many studies are ongoing, more interesting results on these and similar topics are to be expected from Belle in the near future.
References
1.	A. Abashian et al. (Belle Coll.), Nucl. Instr. and Meth. A 479,117 (2002).
2.	J. Brodzicka et al. (Belle Coll.), Phys. Rev. Lett. 100, 092001 (2008).
3.	B. Aubert et al. (BaBar Coll.), Phys. Rev. Lett. 97, 222001 (2006).
4.	V. Balagura, et al. (Belle Coll.), Phys. Rev. D 77, 032001 (2008).
5.	B. Aubert et al. (BaBar Coll.), Phys. Rev. Lett. 102,132001 (2009).
6.	I. Adachi et al. (Belle Coll.), arXiv:0810.0358v2 [hep-ex], to be submitted to Phys. Rev. Lett.
7.	B. Aubert et al. (BaBar Coll.), Phys. Rev. D 77, 011102 (2008).
8.	S.-K. Choi, et al. (Belle Coll.), Phys. Rev. Lett. 100,142001 (2008).
9.	R. Mizuk, et al. (Belle Coll.), Phys. Rev. D 80, 031104 (2009).
10.	R. Mizuk, et al. (Belle Coll.), Phys. Rev. D 78, 072004 (2008).
11.	P. Pakhlov et al. (Belle Coll.), Phys. Rev. Lett. 100, 202001 (2008).
12.	P. Pakhlov, et al. (Belle Coll.), Phys. Rev. D 79, 071101 (2009).
13.	G. Pakhlova, et al. (Belle Coll.), Phys. Rev. Lett. 101,172001 (2009).
14.	E. Swanson, proceedings of the Rencontres de Moriond 2009 Conference (QCD and High Energy Interactions).