Leptonic Decays of Pseudoscalar Mesons: A New Approach

Because quarks in hadronic states are subjected to strong QCD forces, It is not straight-forward to apply calculation obtained at the quark level to physical processes involving hadrons because quarks in hadronic states are subjected to strong QCD forces. In this paper we consider the leptonic decays of pseudoscalar mesons of type M to lepton + antineutrino, where M is pseudoscalar meson with quark contents of. At the quark level, the corresponding process is q1 to q2 + lepton and antineutrino. However, when we fold the quark-level process to the meson decay process, the complication from QCD effects comes in. We make the fundamental assumption that the vertex of type can be approximated by an effective constant gamma-5 coupling. With this assumption, the hadronic process can then be related to the quark-level process. The model is applied to the leptonic decays of pi-meson, K-meson, D-meson, Ds-meson and B-meson.