EFFECTIVE LAGRANGIAN FOR HEAVY AND LIGHT MESONS - RADIATIVE B-DECAYS

We make use of the information obtained from semileptonic decays of B and D mesons, within an effective lagrangian description based on heav y quark theory and on chiral expansion, to study the radiative decays B --> Kgamma and B(s) --> phigamma, and the pair conversion processes B --> Ke+e- and B --> Ke+e-. We discuss with care the required extra polations from zero recoils. We obtain a BR (B --> Kgamma) between 1. 3 x 10(-5) and 4.1 x 10(-5) and BR (B(s) --> phigamma) between 1.4 x 1 0(-5) and 4.5 x 10(-5), with errors mainly arising from the present un certainty in the Kobayashi-Maskawa element \V(ts)\. For the pair conve rsion processes we study in particular the lepton effective mass distr ibutions whose measurements would allow for an understanding of both l ong distance and short distance contributions to such processes.