Exclusive decays of heavy and light mesons

Abstract

In the exclusive decay of the B meson into a ${\mathit{K}}^{\mathrm{*}}$ and a photon, the large recoil momentum creates a difficulty in making a connection between the quark level calculations and the meson states. In the quark model, depending on how the recoil momentum is handled, this can lead to differences of a factor of about 5 in the branching ratio. In order to explore this problem, we look at some other meson processes where there exist some experimental data. For the π form factor we show that, by imposing current conservation together with relativistic meson and spinor normalizations within the quark model, it is possible to remove a parameter κ which had previously been introduced to obtain agreement with the form-factor data. The data on the decay ω→${\mathrm{\pi }}^0$ ${\mathrm{\mu }}^{+}$ ${\mathrm{\mu }}^{\mathrm{-}}$ and ω→${\mathrm{\pi }}^0$γ also show the importance of retaining relativistic meson and spinor normalizations; however, we do not resolve the recoil problem. For the exclusive decays B→${\mathit{K}}^{\mathrm{*}}$γ and B→${\mathit{K}}^{\mathrm{*}}$ ${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$ we show the extent to which the heavy-quark symmetries determine these decays, even in regions of large recoil.