Nonfactorizable B→χc0K decay and QCD factorization

We study the unexpectedly large rate for the factorization-forbidden decay B -> chi K-c0 within the QCD factorization approach. We use a non-zero gluon mass to regularize the infrared divergences in vertex corrections. The end-point singularities arising from spectator corrections are regularized and carefully estimated by the off-shellness of quarks. We find that the contributions arising from the vertex and leading-twist spectator corrections are numerically small, and the twist-3 spectator contribution with chiral enhancement and linear end-point singularity becomes dominant. With reasonable choices for the parameters, the branching ratio for B -> chi K-c0 decay is estimated to be in the range (2 similar to 4) x 10(-4), which is compatible with the Belle and BaBar data.