Cabibbo–Kobayashi–Maskawa-favored B decays to a scalar meson and a D meson

摘要

In this work, we attempt to study the Cabibbo–Kobayashi–Maskawa-favored B→D¯S (“S” denoting the scalar meson) decays within the perturbative QCD approach at the leading order and the leading power. Although the light scalar mesons are widely perceived as primarily the four-quark bound states, in practice it is hard for us to make quantitative predictions based on the four-quark picture for light scalars. Hence, we calculate the decays with light scalars in the two-quark model. For the decays with scalar mesons above 1 GeV, we have explored two possible scenarios, depending on whether the light scalars are treated as the lowest lying qq¯ states or four-quark particles. In total, we calculated the branching fractions of 72 decay modes, and most of them are in the range 10^-4–10^-7, which are measurable in the on-going LHCb experiment and the forthcoming Belle-II experiment. Moreover, since in the standard model these decays occur only through tree operators and have no CP asymmetries, any deviation will be a signal of new physics beyond the standard model. Despite large uncertainties induced by nonperturbative parameters and corrections of high order and high power, our results and discussions will be useful for the on-going LHCb and the forthcoming Belle-II experiments.