WEAK TRANSITIONS OF HEAVY MESONS AND THE QUARK MODEL

We underline the general features of the constituent quark model and its success in the description of the spectrum and transitions of hadrons made up of light or heavy quarks, briefly compared to first principles of QCD. To show the present usefulness of the techniques and intuitive insight of the model we present a semirelativistic quark model of meson form factors that exhibits Isgur-Wise scaling and corrections to it. As examples of applications, we consider semileptonic form factors and non-leptonic decays of heavy flavor mesons. We address the issue of the violation of factorization, and show how the quark model can give hints on the problem.