B -> J/psi K decays in QCD factorization - art. no. 074011

The hadronic decays B --> J/psiK (K*) are interesting because experimentall y they are the only color-suppressed modes which have been measured, and th eoretically they are calculable by QCD factorization even when the emitted meson J/psi is heavy. We analyze the decay B --> J/psiK within the framewor k of QCD factorization. We show explicitly the scale and gamma (5)-scheme i ndependence of decay amplitudes and infrared safety of nonfactorizable corr ections at twist-2 order. Leading-twist contributions from the light-cone d istribution amplitudes (LCDAs) of the mesons are too small to accommodate t he data; the nonfactorizable corrections to naive factorization are small. We study the twist-3 effects due to the kaon and find that the coefficient a(2)(J/psiK) is largely enhanced by the nonfactorizable spectator interacti ons arising from the twist-3 kaon LCDA phi (K)(sigma), which an formally po wer suppressed but chirally, logarithmically, and kinematically enhanced. T herefore, factorization breaks down at twist-3 order. The higher-twist effe cts of J/psi are briefly discussed. Our result also resolves the long-stand ing sign ambiguity of a(2)(J/psiK), which turns out to be positive for its real part.