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arXiv 1006.4231hep-phhep-ex
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相对论夸克模型中B和B_c介子的稀有半轻子衰变

Rare semileptonic decays of B and B_c mesons in the relativistic quark model

D. Ebert, R. N. Faustov, V. O. Galkin

摘要:

在QCD激发的相对论夸克模型框架下,基于准势方法研究了B和B_c介子的稀有半轻子衰变。在考虑相对论效应的情况下,计算了相应介子态之间弱跃迁矩阵元的形状因子,包括中间负能态的贡献和介子波函数的相对论变换.形状因子的动量传递依赖性在整个可访问的运动学范围内被可靠地确定。在此基础上,计算了B_PDMATHABMM K^{(*)} 1 ^+1 ^-(ν \bar ν)和B_c \to D_s^{(*)} 1 ^+1 ^-(ν \bar ν)衰变的总分支率和微分分支率,以及末态矢量介子和μ子前后不对称性A_{FB}的纵向极化率F_L.结果与最近从Belle和CDF得到的B \to K^{(*)}μ^+μ^-衰变的详细实验数据符合得很好,并对B_c介子的罕见半轻子衰变作了预言.

英文摘要:

Rare semileptonic decays of B and B_c mesons are investigated in the framework of the QCD-motivated relativistic quark model based on the quasipotential approach. Form factors parametrizing the matrix elements of the weak transitions between corresponding meson states are calculated with the complete account of the relativistic effects including contributions of intermediate negative energy states and relativistic transformations of the meson wave functions. The momentum transfer dependence of the form factors is reliably determined in the whole accessible kinematical range. On this basis the total and differential branching fractions of the B\to K^{(*)}l^+l^-(ν\barν) and B_c\to D_s^{(*)}l^+l^-(ν\barν), B_c\to D^{(*)}l^+l^-(ν\barν) decays as well as the longitudinal polarization fractions F_L of the final vector meson and the muon forward-backward asymmetries A_{FB} are calculated. Good agreement of the obtained results with the recent detailed experimental data on the B\to K^{(*)}μ^+μ^- decays from Belle and CDF is found. Predictions for the rare semileptonic decays of the B_c mesons are given.

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