重介子弱衰变的系统研究

基于BS理论框架,利用相对论性的组分夸克势模型,系统地研究B、B.、D和D,介子的跃迁(但不包含末态是轻赝标介子的情况),并计算了这些重介子的单举半轻子及2体末态非轻子弱衰变过程的分支比.在B和B.到粲味介子的跃迁中零反冲处的形状因子和他们的斜率都与重夸克有效理论一致;所有半轻子弱衰变的分支比都与实验符合B和B,轻子弱衰变的分支比与实验值相差不足一倍;末态是轻矢量介子时,形状因子与重夸克对称的要求相差很大D和D,非轻子弱衰变的分支比与实验值不符.这些结果还表明,采用的方法和模型能够用于描述重介子和轻矢量介子,而因子化假设在D和D,的情况下远不如在B和B,情况下适用.

A Systematic Study of Heavy Meson Weak Decays

B, Bs, D and Ds transitions except those inio final stare light pseudoscalar mesons are systematically studied in a relativistic constituent quark model based on the BS formalism and the exclusive semileptonic and two-body nonleptonic weak decay widths of these heavy mesons are calculated. Both of the form factrs and their slopes at zero-recoil point for B and Bs transitions into charmed mesons are consistent with HQET Branching fractions for all the semileptonic decays are in good agreement with data, those for the nonleptonic decays of B and Bs mesons are in agreement with data where available within a factor of two. However, the calculated form factors for transitions with final states being light vector mesons deviate HQS a lot. For D and Ds mesons, the nonleptonic decay branching ratios do not respect data. The results mny imply that our approaches and model can be used to describe both heavy mesons and ligh vector mesons, and the factorization scheme is much less applicable in D and Ds decays than in B and Bs decays.