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arXiv 2412.02480hep-phhep-ex
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由遍举半轻子$B$介子衰变测定强耦合常数$α_s$

Determination of the Strong Coupling Constant $α_s$ from Inclusive Semi-leptonic $B$ Meson Decays

Yuzhi Che, Long Chen, Jinfei Wu, Xinchou Lou, Xiang Chen, Xin Guan, Yan-Qing Ma, Manqi Ruan

AI总结:

本文将遍举半轻子$B$衰变宽度表示为$α_s$、$|V_{cb}|$和夸克质量的函数并拟合世界平均数据,测得$α_s(m_Z)=0.1266\pm0.0023$,未来精度有望达约0.0018。

摘要:

我们论证了由$B$介子的遍举半轻子衰变宽度测定强耦合常数$α_s$的可行性。我们将半轻子$B$衰变宽度表示为$α_s(5\\,\mathrm{GeV})$、Cabibbo-Kobayashi-Maskawa矩阵元$|V_{cb}|$以及$\overline{\mathrm{MS}}$方案下$b$夸克和$c$夸克质量的函数。我们用$B^{\pm}$和$B^{0}$半轻子衰变宽度的当前世界平均值拟合$α_s(5\\,\mathrm{GeV})$。由此得到$α_s(5\\,\mathrm{GeV})=0.245\pm0.009$,对应于外推到5味的$α_s(m_Z)=0.1266\pm0.0023$。主要的不确定性贡献来自微扰展开的不确定性和$|V_{cb}|$的取值。未来的进展,包括更高阶微扰计算,以及即将建成的$B$工厂和$Z$工厂对$|V_{cb}|$和$B$衰变宽度的精确测量,可使该方法以$Δα_s(m_Z)\sim0.0018$这一具有竞争力的精度测定$α_s(m_Z)$。这一精度可与目前由$τ$轻子衰变测量$α_s(m_Z)$的准确度相比,后者被认为是最精确的实验方法。

英文摘要:

We demonstrate the feasibility of determining the strong coupling constant, $α_s$, from the inclusive semileptonic decay width of $B$ mesons. We express the semileptonic $B$ decay width as a function of $α_s(5\mathrm{\,GeV})$, the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$, $b$- and $c$-quark masses in the $\overline{\mathrm{MS}}$ scheme. We fit $α_s(5\mathrm{\,GeV})$ to current world averages of the $B^{\pm}$ and $B^{0}$ semileptonic decay widths. This yields $α_s(5\mathrm{\,GeV}) = 0.245 \pm 0.009$, corresponding to a 5-flavor extrapolation of $α_s(m_{Z}) = 0.1266 \pm 0.0023$. The primary uncertainty contributions arise from the uncertainty on the perturbative expansion and the value of $|V_{cb}|$. Future advancements including higher-order perturbative calculations, and precise measurements of $|V_{cb}|$ and $B$ decay widths from upcoming $B$ and $Z$ factories, could enable this method to determine $α_s(m_{Z})$ with a competitive precision of $Δα_s(m_{Z}) \sim 0.0018$. This precision is comparable to the current accuracy of $α_s(m_{Z})$ measurements from $τ$-lepton decays, which is regarded as the most precise experimental approach.

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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