Exclusive versus Inclusive Semileptonic $\bar B$ Decays in the Quark   Model
  Some emerging difficulties in the theoretical description of exclusive semileptonic $\bar B$ decays are discussed in the context of the quark model. While there are no unambiguous problems at this time, I discuss physics beyond the valence quark model which should eventually be probed by precision measurements of $\bar B$ semileptonic decays. 
Nathan Isgur