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arXiv 2501.09090hep-ph
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$\bar{B}\to X_c \bar{\nu}_\nu$的运动学矩至$\boldsymbol{\bar{B}\to X_c \bar{\nu}_\nu}$阶

Kinematic Moments of $\bar{B}\to X_c \ell \barν_\ell$ to Order $\mathcal{O}(Λ_{\rm QCD}^5/m_b^5)$

Gael Finauri

AI总结:

本研究计算了含粲半轻$\bar{B}$衰变直至$\boldsymbol{\bar{B}\to X_c \bar{\nu}_\nu}$阶的全微分衰变率,给出多种运动学矩的解析结果,分析了理论误差,并指出CLEO数据与理论的差异推动新测量以提升$|V_{cb}|$的确定精度。

摘要:

我们在树图水平下研究含粲半轻$\bar{B}$衰变的重夸克展开(HQE),计算了直至$\boldsymbol{\bar{B}\to X_c \bar{\nu}_\nu}$阶的全微分散射率。我们给出了$\bar{B}$静止系中带轻子能量下限截断的轻子能量、强子不变质量和轻子不变质量($q^2$)的前三个矩的解析结果,以及带$q^2$下限截断的前三个$q^2$矩的解析结果。借助最低态饱和假设,我们研究了重夸克展开(HQE)的数值行为,揭示了与幂次修正相关的理论误差预算。现有的CLEO实验关于带轻子能量下限截断的二阶中心$q^2$矩的数据,与理论预期存在令人困惑的差异。这一观测结果使得对这些可观测量进行新的测量成为必要,这将有助于提高用于含粲衰变确定$|V_{cb}|$的全局拟合分析的精度。

英文摘要:

We investigate the heavy-quark expansion (HQE) for inclusive semileptonic $\bar{B}$ decays, at tree level, by computing the fully differential decay rate up to order $\mathcal{O}(Λ_{\rm QCD}^5/m_b^5)$. We provide analytic results for the first three moments in the lepton energy, hadronic invariant mass and leptonic invariant mass ($q^2$) with a lower cut on the lepton energy in the $\bar{B}$ rest frame, as well as for the first three $q^2$ moments with a lower cut on $q^2$. By means of the lowest-lying state saturation ansatz we study the numerical behaviour of the HQE providing insights into the theoretical error budget associated with power corrections. Available CLEO data on the second central $q^2$ moment with a lower cut on the lepton energy present puzzling discrepancies with the theoretical expectations. This observation makes new measurements of these observables desirable, which could improve the precision of global fit analyses for the inclusive determination of $|V_{cb}|$.

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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