Decays of b hadrons and a possible new four-quark interaction
  A possibility is considered of explaining the low experimental value of the ratio of the lifetimes tau(Lambda_b)/tau(B_d) by a new `centiweak' four-quark interaction, i.e with a strength on the order of 10^{-2}G_F. It is noted that the considered interaction can also improve agreement with the data on low semileptonic branching ratio B_{sl}(B) in B meson decays with a simultaneous slight decrease in the prediction for the average charm yield in those decays. The proposed new interaction modifies within the present experimental limits the predictions for differences of lifetimes among B mesons, and can thus be probed by more precise data on these differences. A sample model is briefly discussed, where the new interaction arises through a weak SU(2) singlet scalar field with quantum numbers of a diquark. 
M.B. Voloshin