Nonspectator Effects and B Meson Lifetimes
  We review the B meson lifetime problems and nonspectator effects. The predictions of B meson lifetime ratios depend on four unknown hadronic parameters $B_1$, $B_2$, $\epsilon_1$ and $\epsilon_2$, where $B_1$ and $B_2$ parametrize the matrix elements of color singlet-singlet four-quark operators and $\epsilon_1$ and $\epsilon_2$ the matrix elements of color octet-octet operators. To understand contributions of the nonspectator effects to the B meson lifetime ratios, we derive the renormalization-group improved QCD sum rules for these parameters within the framework of heavy quark effective theory. 
Kwei-Chou Yang