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arXiv 2012.10440hep-phhep-ex
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一种改进的$τ$矢谱函数的强耦合

The strong coupling from an improved $τ$ vector isovector spectral function

Diogo Boito, Maarten Golterman, Kim Maltman, Santiago Peris, Marcus V. Rodrigues, Wilder Schaaf

备注：
38 pages, 8 figures, published version
发表信息：
Phys. Rev. D 103, 034028 (2021)
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摘要：

我们结合ALEPH和OPAL测量的$τ\toπ^-π^0ν_τ$，$τ\to 2π^-π^+π^0ν_τ$和$τ\toπ^-3π^0ν_τ$衰变的光谱分布的结果与（一）最近的BaBar结果类似的$τ\to K^- K^0ν_τ$分布和（ii）估计的贡献从其他强子$τ$ -衰变模式获得使用CVC和电产生数据，以获得一个新的和更精确的非奇怪的，包容性的矢量，等矢量谱函数。BaBar $K^- K^0$和CVC/电生产结果为我们提供了替代的、完全基于数据的输入，用于ALEPH和OPAL采用基于蒙特卡罗的估计的所有排他性模式的贡献。我们使用由此产生的光谱函数，以确定$α_s(m_τ)$，在$τ$质量尺度的强耦合，采用有限的能量和规则。使用固定阶微扰理论（FOPT）处方，我们发现$α_s(m_τ)=0.3077\pm 0.0075$，这对应于五味结果$α_s(M_Z)=0.1171\pm 0.0010$在$Z$质量。虽然我们也提供了一个估计使用轮廓改进的扰动理论（CIPT），我们指出，FOPT处方是首选的比较与其他$α_s$测定采用的$\overline{\rm MS}$计划，特别是考虑到CIPT和标准的运营商产品的扩展最近在文献中指出的不一致。对主要$2π$和$4π$模式的额外实验输入将允许对当前分析的进一步改进。

英文摘要：

We combine ALEPH and OPAL results for the spectral distributions measured in $τ\toπ^-π^0ν_τ$, $τ\to 2π^-π^+π^0ν_τ$ and $τ\toπ^-3π^0ν_τ$ decays with (i) recent BaBar results for the analogous $τ\to K^- K^0ν_τ$ distribution and (ii) estimates of the contributions from other hadronic $τ$-decay modes obtained using CVC and electroproduction data, to obtain a new and more precise non-strange, inclusive vector, isovector spectral function. The BaBar $K^- K^0$ and CVC/electroproduction results provide us with alternate, entirely data-based input for the contributions of all exclusive modes for which ALEPH and OPAL employed Monte-Carlo-based estimates. We use the resulting spectral function to determine $α_s(m_τ)$, the strong coupling at the $τ$ mass scale, employing finite energy sum rules. Using the fixed-order perturbation theory (FOPT) prescription, we find $α_s(m_τ)=0.3077\pm 0.0075$, which corresponds to the five-flavor result $α_s(M_Z)=0.1171\pm 0.0010$ at the $Z$ mass. While we also provide an estimate using contour-improved perturbation theory (CIPT), we point out that the FOPT prescription is to be preferred for comparison with other $α_s$ determinations employing the $\overline{\rm MS}$ scheme, especially given the inconsistency between CIPT and the standard operator product expansion recently pointed out in the literature. Additional experimental input on the dominant $2π$ and $4π$ modes would allow for further improvements to the current analysis.

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