Spectator and Non-Spectator Models in the B Meson Systems

If the charged and neutral B mesons have the same lifetimes, as predicted by the spectator model, the semileptonic branching ratio of B → evX will not satisfy the experimental results. After the contribution from the non-spectator (W-exchange) model is included, the semileptonic branching ratio of B mesons will be within the experimental region, and the sizable lifetime difference between B d 0 and B ± mesons is predicted.