Measurement of branching fractions for B→χc1(2)K(K∗)B→χc1(2)K(K∗) at Belle

We have measured the branching fractions for the exclusive decay modes B→χc1(2)K(K∗)B→χc1(2)K(K∗) using a 140 fb−1140 fb−1 data sample collected by the Belle detector at the KEKB asymmetric-energy e+e−e+e− collider. The measured branching fractions for B+→χc1K+B+→χc1K+, B0→χc1K0B0→χc1K0, B0→χc1K∗0B0→χc1K∗0 and B+→χc1K∗+B+→χc1K∗+ decay modes are (4.5±0.2±0.5)×10−4(4.5±0.2±0.5)×10−4, (3.5±0.3±0.5)×10−4(3.5±0.3±0.5)×10−4, (3.1±0.3±0.7)×10−4(3.1±0.3±0.7)×10−4 and (4.1±0.6±0.9)×10−4(4.1±0.6±0.9)×10−4, respectively, where the first error is statistical and the second error is systematic. We do not observe statistically significant signals for the B→χc2K(K∗)B→χc2K(K∗) decay modes and set upper limits at the 90% confidence level. We also study the helicity distribution for B→χc1K∗B→χc1K∗ decay mode and show that the longitudinal polarization component is dominant.