关于B^0→π^-^+■_衰变过程分支比的计算

Research on branching ratio of B^0→π^-^+■_ decay

通过构造适当的关联函数,计算B→π跃迁形状因子fB+π(q2),fBπ(q2)和标量形状因子f0(q2),从而就能研究轻子质量对B0→π-+ν(l=e,μ,τ)衰变过程的影响.首次分别计算B0→π-e+νe,B0→π-μ+νμ,B0→π-τ+ντ衰变过程的分支比,并发现轻子质量me,mμ可以忽略,但重轻子质量mτ不能忽略,它对分支比计算有一定的贡献.把计算结果与最近的实验数据进行比较,发现理论结果与实验数据基本符合.

We choose a correlation function of chiral current to calculate the form factors f B＋π（q2）,f～Bπ（q2） and the scalar form factor of f 0（q2）,thereby we can study the effect of leptonic mass on B0 →π-＋ν（l = e,μ,τ） decay.In this paper,we calculate the branching ratio of B0 →π-＋ ν（l = e,μ,τ） decay for the first time,and find the leptonic mssses me and mμ may be ignored,but the heavy leptonic mass mτ may not be ignored and it can affect the branching ratio.The calculation results are consistent with the experimental data.