We present the results of an amplitude analysis of B¯0→J/ψK-π+ decays. A new charged charmoniumlike state Zc(4200)+ decaying to J/ψπ+ is observed with a significance of 6.2σ. The mass and width of ...the Zc(4200)+ are 4196+31-29+17-13 MeV/c2 and 370+70-70+70-132 MeV, respectively; the preferred assignment of the quantum numbers is JP=1+. In addition, we find evidence for Zc(4430)+→J/ψπ+. The analysis is based on a 711 fb-1 data sample collected by the Belle detector at the asymmetric-energy e+e- collider KEKB.
A
bstract
We report a search for
B
decays to selected final states with the
η
c
meson:
B
±
→
K
±
η
c
π
+
π
−
,
B
±
→
K
±
η
c
ω
,
B
±
→
K
±
η
c
η
and
B
±
→
K
±
η
c
π
0
. The analysis is based on 772 × ...10
6
B
B
¯
pairs collected at the Υ(4
S
) resonance with the Belle detector at the KEKB asymmetric-energy
e
+
e
−
collider. We set 90% confidence level upper limits on the branching fractions of the studied
B
decay modes, independent of intermediate resonances, in the range (0
.
6–5
.
3) × 10
−4
. We also search for molecular-state candidates in the
D
0
D
¯
∗
0
−
D
¯
0
D
∗
0
,
D
0
D
¯
0
+
D
¯
0
D
0
and
D
∗
0
D
¯
∗
0
+
D
¯
∗
0
D
∗
0
combinations, neutral partners of the
Z
(3900)
±
and
Z
(4020)
±
, and a poorly understood state
X
(3915) as possible intermediate states in the decay chain, and set 90% confidence level upper limits on the product of branching fractions to the mentioned intermediate states and decay branching fractions of these states in the range (0
.
6–6
.
9) × 10
−5
.
We detail the analysis of the three-body e+e- → B B ¯ π± , B B ¯ *π± , and B* B ¯ *π± processes, including the first observations of the Zb± ( 10610 ) → B B ¯ *+ c . c . ± and Zb± ( 10650 ) → B* B ...¯ * ± transitions that are found to dominate the corresponding final states. We measure Born cross sections for the three-body production of σ ( e+e- → B B ¯ *+ c . c . ±π∓ ) = 17.4±1.6 ( stat ) ±1.9 ( syst ) pb and σ ( e+e- → B* B ¯ * ±π∓ ) = 8.75±1.15 ( stat ) ±1.04 ( syst ) pb and set a 90% C.L. upper limit of σ ( e+e- → B B ¯ ±π∓ ) <2.9 pb . The results are based on a 121.4 fb-1 data sample collected with the Belle detector at a center-of-mass energy near the Υ ( 10860 ) peak.