We study the branching ratios of D^＋ → D^0e^＋ν, Ds^＋ → D^0e^＋ν, Bs^0→B^＋e^-^-ν, Ds^＋→D^＋e^-e^＋ and Bs^0→B^0e^-e^＋ rare semileptonic decay processes, which are induced by decays of light quarks, the heavy quarks remain unchanged. The branching ratios of these decay processes are estimated in the heavy quark limit and with SU（3） flavor symmetry. We find that the decay rates are very tiny in the framework of the Standard Model. We also estimate the sensitivities of the measurements of these rare decays at the future experiments, such as BES-Ⅲ, super-B and LHC-b. Observations of these decays may shed some light on new physics beyond the standard model.
The possibility of studying D 0-D 0 mixing at a giga-Z linear collider "Z factory" where 10 9 hadronic Z 0 decays can be accumulated is examined.We discuss the sensitivity for the measurements of neutral D mixing parameters.These results are compared to those attainable at B factories.We find that the typical decay length of the neutral D mesons at Z factory is about 10 times larger than that at B factory.In addition,the resolution of the vertex detector of a giga-Z factory is 2-3 times better than that of B factory.The proper time resolution at Z factory is about 20-30 times better than that at B factory.Therefore the determination of the mixing parameters at a giga-Z factory is more precise.
LI HaiBo 1 & YANG MaoZhi 2 1 Institute of High Energy Physics,P.O.Box 918,Beijing 100049,China
We study the heavy-light mesons in a relativistic model, which is derived from the Bethe-Salpeter equation by applying the Foldy-Wouthuysen transformation to the heavy quark. The kernel we choose is based on scalar confinement and vector Coulomb potentials. The transverse interaction of the gluon exchange is also taken into account in this model. The spectra and wave functions of D, Ds, B, Bs meson states are obtained. The spectra are calculated up to the order of 1/mQ, and wave functions are treated to leading order.
