论文标题
MUON $ g $ -2和$Δα$连接
The muon $g$-2 and $Δα$ connection
论文作者
论文摘要
标准模型理论与MUON磁矩异常的实验测量之间的差异，$A_μ= \ left（G_μ-2\右）/2 $，通过其对HADRONIC真空偏置效应的共同依赖性连接到Precision Electroweak（EW）预测。总计$ e^+e^ - \ rightarrow \ text {hadrons} $横截面，$σ_ {\ rm ave}（s）$的$σ_{\ rm，用作输入分散关系，以估算Hadronic真空化的贡献，$a_μ^{\ rm，\ rm，\ rm fortir fortir fortir fortir fortir fortrif for。在$ z $ -pole，$Δα_ {\ rm ave}^{（5）}（m_ {z}^2）$中耦合，它进入自然关系和全局ew。 $δα_ {\ rm的EW拟合预测具有}^{（5）}（m_ {z}^2）= 0.02722（41）$与$Δα_{\ rm head}^（5）}（5）}（m_ {z}^2）= 0.02761 $ gentiration（5）^rm hase} $Δ中心值暗示了较大的差异$ΔA_μ=a_μ^{\ rm exp}-A_μ^{\ rm sm} $。假设$ΔA_μ$差异可能是由于缺少$σ_ {\ rm有}（s）$贡献，对$ m_w $，$ \ sin^2 \！研究了θ^{\ rm lep} _ {\ rm eff} $和从全局EW拟合中获得的$ m_h $。在95 \％cl上，发现bridge $ΔA_μ$ $σ_ {\ rm ave}（s）$被排除在$ \ sqrt {s} \ gtrsim 0.7 $ gtrsim 0.7 $ gtrsim 0.7 $ gtrsim。此外，鉴于横截面所需的增加，$ΔA_μ$的前景被认为是不可能的。还发现了对HADRONIC数据的这种假设变化会影响其他相关的可观察物，例如电子异常，$ a_e^{\ rm sm} $，比率$ r_ {e/μ} =（m_μ/m_e）^2（a_} \ \，lo \，vp}）$和低能弱混合角的运行，尽管这些后果目前的约束较少。
The discrepancy between the Standard Model theory and experimental measurement of the muon magnetic moment anomaly, $a_μ=\left(g_μ-2\right)/2$, is connected to precision electroweak (EW) predictions via their common dependence on hadronic vacuum polarization effects. The same data for the total $e^+e^- \rightarrow \text{hadrons}$ cross section, $σ_{\rm had}(s)$, are used as input into dispersion relations to estimate the hadronic vacuum polarization contributions, $a_μ^{\rm had,\,VP}$, as well as the five-flavor hadronic contribution to the running QED coupling at the $Z$-pole, $Δα_{\rm had}^{(5)}(M_{Z}^2)$, which enters natural relations and global EW fits. The EW fit prediction of $Δα_{\rm had}^{(5)}(M_{Z}^2) = 0.02722(41)$ agrees well with $Δα_{\rm had}^{(5)}(M_{Z}^2) = 0.02761(11)$ obtained from the dispersion relation approach, but exhibits a smaller central value suggestive of a larger discrepancy $Δa_μ=a_μ^{\rm exp} - a_μ^{\rm SM}$ than currently expected. Postulating that the $Δa_μ$ difference may be due to missing $σ_{\rm had}(s)$ contributions, implications for $M_W$, $\sin^2 \! θ^{\rm lep}_{\rm eff}$ and $M_H$ obtained from global EW fits are investigated. Shifts in $σ_{\rm had}(s)$ needed to bridge $Δa_μ$ are found to be excluded above $\sqrt{s} \gtrsim 0.7$ GeV at the 95\%CL. Moreover, prospects for $Δa_μ$ originating below that energy are deemed improbable given the required increases in the cross section. Such hypothetical changes to the hadronic data are also found to affect other related observables, such as the electron anomaly, $a_e^{\rm SM}$, the ratio $R_{e/μ} = (m_μ/m_e)^2 (a_{e}^{\rm had,\,LO\,VP}/a_μ^{\rm had,\,LO\,VP})$ and the running of the weak mixing angle at low energies, although the consequences of these are currently less constraining.
