We report an observation of the B±→J/ψηK± and B0→J/ψηKS0 decays using 772×106BBˉ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We obtain the branching fractions B(B±→J/ψηK±)=(1.27±0.11(stat.)±0.11(syst.))×10−4 and B(B0→J/ψηKS0)=(5.22±0.78(stat.)±0.49(syst.))×10−5. We search for a new narrow charmonium(-like) state X in the J/ψη mass spectrum and find no significant excess. We set upper limits on the product of branching fractions, B(B±→XK±)B(X→J/ψη), at 3872 MeV/c2 where a C-odd partner of X(3872) may exist, at ψ(4040) and ψ(4160) assuming their known mass and width, and over a range from 3.8 to 4.8 GeV/c2. % at a 5 MeV/c2 step. The obtained upper limits at 90% confidence level for XC−odd(3872), ψ(4040) and ψ(4160) are 3.8×10−6, 15.5×10−6 and 8.1×10−6, respectively
We report inclusive and exclusive measurements for χc1 and χc2 production in B decays. We measure B(B→χc1X)= (3.03 \pm 0.05(\mbox{stat}) \pm 0.24(\mbox{syst})) \times 10^{-3} and B(B→χc2X)= (0.70 \pm 0.06(\mbox{stat}) \pm 0.10(\mbox{syst})) \times 10^{-3}. For the first time, χc2 production in exclusive B decays in the modes B0→χc2π−K+ and B+→χc2π+π−K+ has been observed, along with first evidence for the B+→χc2π+KS0 decay mode. For χc1 production, we report the first observation in the B+→χc1π+π−K+, B0→χc1π+π−KS0 and B0→χc1π0π−K+ decay modes. Using these decay modes, we observe a difference in the production mechanism of χc2 in comparison to χc1 in B decays. In addition, we report searches for X(3872) and χc1(2P) in the B+→(χc1π+π−)K+ decay mode. The reported results use 772×106BB events collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider