Four-quark operators relevant to B meson lifetimes from QCD sum rules

At the order of 1/m(b)(3), the B meson lifetimes are controlled by the hadronic matrix elements of some four-quark operators. The nonfactorizable magnitudes of these four-quark operator matrix elements are analyzed by QCD sum rules in the framework of heavy quark effective theory. The vacuum saturation for color-singlet four-quark operators is justified at the hadronic scale, and the nonfactorizable effect is at a few percent level. However, for color-octet four-quark operators, the vacuum saturation is violated sizably so that the nonfactorizable effect cannot be neglected for the B meson lifetimes. The implication to the extraction of some of the parameters from B decays is discussed. The B meson lifetime ratio is predicted as tau(B-)tau(B-o) = 1.09 +/- 0.02. However, the experimental result of the lifetime ratio tau(Lambda(b))/tau(B-o) still cannot be explained. [S0556-2821(98)03607-8].