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arXiv 1609.00199hep-phhep-ex
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相对论夸克模型中$Λ_b$重子的半轻子衰变

Semileptonic decays of $Λ_b$ baryons in the relativistic quark model

R. N. Faustov, V. O. Galkin

摘要:

在相对论夸克模型的框架下,利用重子的夸克-双夸克图像,采用准势方法研究了半轻子$Λ_b$衰变。衰变形状因子由初、末态重子波函数的重叠积分表示。所有的计算都没有使用非相对论性和重夸克展开。衰变形状因子的动量传递依赖性在整个可达运动学范围内明确确定,而无需任何外推或模型假设。计算了重-重$Λ_b\toΛ_c\ellν_\ell$和重-轻$Λ_b\to p\ellν_\ell$衰变分支分数。结果与$Λ_b\toΛ_c^+l^-\barν_l$衰变的分支分数的实验值在误差条内一致。根据最近LHCb实验得到的重-轻和重-重半轻子$Λ_b$衰变的分支比数据,得到了Cabbibo-Kobayashi-Maskawa矩阵元$|V_{ub}|/|V_{cb}|$的比值.这与由包含的$B$介子衰变所确定的相应比率是一致的。

英文摘要:

Semileptonic $Λ_b$ decays are investigated in the framework of the relativistic quark model based on the quasipotential approach and the quark-diquark picture of baryons. The decay form factors are expressed through the overlap integrals of the initial and final baryon wave functions. All calculations are done without employing nonrelativistic and heavy quark expansions. The momentum transfer dependence of the decay form factors is explicitly determined in the whole accessible kinematical range without any extrapolations or model assumptions. Both the heavy-to-heavy $Λ_b\toΛ_c\ellν_\ell$ and heavy-to-light $Λ_b\to p\ellν_\ell$ decay branching fractions are calculated. The results agree within error bars with the experimental value of the branching fraction of the $Λ_b\toΛ_c^+l^-\barν_l$ decay. From the recent LHCb data on the ratio of the branching fractions of the heavy-to-light and heavy-to-heavy semileptonic $Λ_b$ decays the ratio of the Cabbibo-Kobayashi-Maskawa matrix elements $|V_{ub}|/|V_{cb}|$ is obtained. It is consistent with the corresponding ratio determined from the inclusive $B$ meson decays.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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