1. Charmonia, Bottomonia and Exotic States at Belle
Patricia Francisconi
Institute for High Energy Physics,
Nikolsdorfergasse 18, 1050 Vienna - Austria
This talk will review the latest results for Charmonia, Bottomonia and Exotic States at Belle.
The measurements described in this review include results for possibly exotic charmonium-like
states like X,Y,Z as well as e+
e → ηJ/ψ via Initial State Radiation (ISR) and B → χc1,2γK.
Furthermore the decay B0
→ J/ψKπ+
is looked at and first evidence for ηb(2S) was found.
Results for exotic bottomonia-like states include Y (nS)π+
π through Z+
b hb(mP)π+
π through
Z+
b will be described as well.
1 Introduction
Heavy quarkonia play an important role in several high energy experiments and are an ideal
tool for testing QCD.
A multitude of charmonium-like states have been discovered at B-factories and a great quantity
of impressively accurate data is being collected and analyzed.
Various conventional cc-bar states have been found and their spectra updated as well as new
discoveries of states, production mechanisms and decays made.
Heavy quarkonium has become a relevant tool in the advancement of our understanding of strong
interactions and the control of some parameters of the Standard Model.
Possible indications for exotic states have been found with the so-called XYZ-states, as well as
Bottomonium-like states. Here I will briefly review some of the recent results obtained at Belle.
2 XYZ - States
In the constituend quark model, mesons are described as ¯qq states. The self-interaction of gluons
however, suggests additional multiquark color singlet states like tetraquarks or molecular bound
states for example, as well as hybrids and various others.
Since the charmonium spectrum can be predicted accurately and conventional ¯cc states are well
described in quark potential models.
At B-Factories like Belle and BaBar some new resonances above open charm theshold have been
discovered in recent years, which do not seem to fit the ¯cc spectrum. These charmonium-like
resonances could be candidates for regular or excited charmonium states, the above mentioned
exotic states can not yet be entirely ruled out.
Quantum numbers have not yet been completely determined for all of the so-called XYZ- states
but precise measurements are underway.

2. 2.1 X(3872)
Due to the even C of X(3872) a C-odd partner would be expected in the tetraquark hypothesis,
that can decay into a J/ final state.
The limit set by BaBar is currently at B(B → X(3872)K)×B(X(3872)J/ψη) < 7.7×106with82fb1.
The Belle data allows an incredibly precise measurement of the branching fraction and enables
the search for some unknown exotic particle which may decay into J/ψη. 5
A strong signal was observed and its mass and width determined to M(X(3872) = 3871.67±0.17
MeV and Γ(X(3872) < 1.2 MeV respectively. Its charge was found to be C = +1 but a C = 1
partner or charged partner have not been observed so far.
2.2 Y Series
On 673 fb1, Y(4260), Y(4360), Y(4660) and other states were studies and their masses and
widths were determined to be M(Y (4360)) = 4361 ± 9 ± 9, Γ(Y (4360)) = 74 ± 15 ± 10,
M(Y (4660)) = 4664 ± 11 ± 5 and Γ(Y (4660)) = 48 ± 15 ± 3.
Charged Z states Z(4430)+, Z(4050)+, Z(4250)+ were observed as well as a new charmonia
state X(3915) in the two photon process, γγ → J/ψω. Candidates for J are 0 or 2, the angular
analysis is ongoing. Its mass and width were determined to be M = 391532 MeV and Γ = 17103
MeV respectively. 5
3 e+e → ηJ/ψ via Initial State Radiation (ISR)
Y family states were found in ψπ+π studied via ISR and e+e → γISRηJψ measured, with
η reconstructed from π+ππ0 and γγ final states on a full data sample taken at Belle of 771.6
+/− 10.6 million ¯BB events at (4S). Unbinned maximum likelihood fit to J/ was performed
with a Breit-Wigner function of resonance decaying into final state. The determined masses and
widths are in good agreement with ψ(4040) and ψ(4160) and the branching fraction was mea-
sured to be B(ψ(4040) → ηJψ) = (0.620.17)% → usingΓe+e(ψ(4040)) = (0.860.07) keV/c from
PDG or B(ψ(4040) → ηJψ) = (1.220.26)%. For B(ψ(4160) → ηJψ) a result of (0.410.12)% or
(1.420.28)% was obtained using PDG average Γe+e(ψ(4160)) = (0.830.07)keV/c2.
The statistical significance was found to be 7.5σ and 7.7σ of ψ(4040) and ψ(4160) respectively,
with a systematic Error of 8.7%. The branching ratios imply widths of 1 MeV for J/ψη transi-
tions which are quite large for charmonia above ¯DD∗ threshold. 3

3. 4 B → χc1,2 γ K
A study of B meson decay into χc1 γK and χc2 γK search for X(3872) partner with C-parity =
-1 and/or missing D-wave charmonia expected to be bigger than 3.8GeV .
Calculation of branching fractions were performed for B → ψ (→ χc1 γ)K and B → ψ‘(→
χc2 γ)K on the final Belle (4S) dataset (771.6 ± 10.6 million).
Signal and background were studied using Monte Carlo and the difference in scale with the Data
callibrated with ψ Evidence of 2 → χc1 γ was found but no no X(3872) signal.
A fit was performed in 2D M(χc1,2γ) for Mbc and the masses and widths calculated to be M1 =
4051±14+20
−41MeV/c2, Γ1 = 82+21+47
−17−22MeV, M2 = 4248+44+180
−29−35 MeV/c2, and Γ2 = 177+54+316
−39−36 MeV ;
Product branching fractions of B( ¯B0 → KZ+
1,2) × B(Z+
1,2 → π+χc1 ) = (3.0 + 1.5 + 3.7) × 105
and (4.0 + 2.30.5) × 105 respectively. 4
Figure 1: Fit to M(χc1 γ), signal: red dashed for B±
→ ψ (→ χc1 γ)K±
, pink: B±
→ X(3820)(→ χc1 γ)K±
,
purple dashed: BG components for B±
→ ψ‘(→ χc1 γ)K±
, cyan dashed: rest of BG
5 B0 → J/ψK−π+
Charged (exotic) Z+ states were observed by Belle in ψ π+, χc1 π+ but have not yet been con-
firmed by Babar.
A search for Z+ → J/ψπ+ via 4D amplitude analysis B0 → J/ψKπ+ and all known K∗ → Kπ
amplitudes included in signal fit as well as Z+ contribution added.
The analysis is based on 711 fb1 data sample collected by the Belle detector on the asymmetric
e+e collider KEKB.
Gaussian signal and 3rd order polynomial background dirstribution were used in the fit and
the amplitude for the three-body decay B0 → J/ψK+ is represented as sum of Breit-Wigner
contributions. 6

4. 6 first evidence for ηb(22)
The used data was collected at Y(5S) and a first evidence for ηb(2S) using hb(2P) → ηb(2S)γ
was seen, as well as a first observation of hb(1P) → ηb(1S)γ and hb(2P) → ηb(1S)γ. Mass
and width of ηb(1S) and ηb(2S) was measured to be mηb
(1S) = 9402.4 ± 1.5 ± 1.8MeV/c,
mηb
(2S) = 9999.0 ± 3.5 ± 2.8MeV/c and Γηb(1S) = 10.8 + 4.0 + 4.5MeV .
The results are in better agreement with theory and the branching fractions larger than expected:
Bhb
(2P) → ηb(2S)γ = (47.5 ± 10.5 ± 6.8) An update to hb(1P) and hb(2P) mass measurements
has been obtained as well on a 133.4 fb1 data sample, at energies near Y(5S) resonance from
Belle detector at the KEKB, which calculated the largest data set at Y(5S) and provides a clean
source for bottonium spectrum. [ 1]
Figure 2: Dalitz plots for Y (nS)π+
π events in (a) Y(1S); (b) Y(2S); (c) Y(3S) signal regions
7 Y (nS)π+π− through Z+
b and hb(mP)π+π through Z+
b
A Belle 121−1fb was used and two horizontal bands in π±
max fitted with: A = A(Z+) + A(Z+) +
A(f(980)) + A(f2(1270)) + A(NR).
JP was assumed to be 1+ and an angular analysis performed.
Possible interpretations for Z+ include a molecule, coupled channel resonance or a tetraquark
state. 2
Figure 3: Dalitz plots for Y (nS)π+
π events in (a) Y(1S); (b) Y(2S); (c) Y(3S) signal regions
References
1. R. Mizuk, et al. arxiv.org/abs/1205.6351v1
2. I. Adachi, et al. arxiv.org/abs/1105.4583v3
3. C.Z. Yuan, et al. arXiv.org/abs/0709.2565v2
4. R. Mizuk, R. Chistov, et al. arXiv.org/abs/0806.4098v3
5. R. Mizuk, R. Chistov, et al. Belle Note No.1196
6. The Belle Collaboration: BN1196, BN1227, BN1200