２００１年度 東大駒場原子核理論セミナー

B中間子の光円錐波動関数と heavy quark symmetry

We investigate the B meson light-cone distribution amplitudes in the heavy-quark limit, which are relevant for the QCD factorization approach for the hard exclusive processes. We derive exact relations between two- and three-particle distribution amplitudes from the equations of motion and heavy-quark symmetry constraint. As solution of these relations, we give representations for the quark-antiquark distribution amplitudes in terms of independent dynamical degrees of freedom. In particular, we find that the Wandzura-Wilczek-type contributions are determined uniquely in analytic form in terms of \bar{\Lambda}, a fundamental mass parameter of heavy-quark effective theory, and that both leading- and higher-twist distribution amplitudes receive the contributions of multi-particle states with additional gluons. Our results are relevant for a range of phenomenologically interesting processes like the exclusive B meson decays and the heavy-meson pair production in e^+ e^- collisions. (Reference : H. Kawamura, J. Kodaira, C.-F. Qiao, and K. Tanaka, hep-ph/0109181)