论文标题
两杆贡献对辐射真空极化的贡献
Isospin-breaking effects in the two-pion contribution to hadronic vacuum polarization
论文作者
论文摘要
如果与$ρ（770）$和$ω（782）$ resonances的干扰有关，则可以共同增强对辐射真空极化（HVP）的两杆贡献（HVP）的贡献。该特定的Ib对茶矢量形式的贡献，因此可以由$ e^+e^ - \至π^+π^ - $的线形状由$ω$ pole的残基描述 - $ρ$ - $ρ$ - $ω$混合参数$ε_Ω$。在这里，我们认为，尽管总体分析性要求此参数是真实的，但辐射通道$π^0γ$，$ππγ$，$ηγ$可以诱导一个小阶段，我们的大小估计为$Δ_im= 3.5（1.0）^\ Circ $，通过使用狭窄的近似近似近似近似近距离，用于中间位于中间位于中间位于中间的Vector vector-vector vector vector vector Mess。然后，我们对$ e^+e^ - \ toπ^+π^ - $数据库进行拟合，并研究对哑光异常磁矩贡献的后果，其IB部分是由于$ρ$ - $ω$混合以及$ω$ chosonance的质量。我们发现，全局拟合确实更喜欢$δ_ε= 4.5（1.2）^\ Circ $的非呈差值值，接近狭窄的共振期望，但是数据集之间的差异很大，表明$ρ$ -CH $ - $ω$区域的系统差异。
Isospin-breaking (IB) effects in the two-pion contribution to hadronic vacuum polarization (HVP) can be resonantly enhanced, if related to the interference of the $ρ(770)$ and $ω(782)$ resonances. This particular IB contribution to the pion vector form factor and thus the line shape in $e^+e^-\to π^+π^-$ can be described by the residue at the $ω$ pole - the $ρ$-$ω$ mixing parameter $ε_ω$. Here, we argue that while in general analyticity requires this parameter to be real, the radiative channels $π^0γ$, $ππγ$, $ηγ$ can induce a small phase, whose size we estimate as $δ_ε=3.5(1.0)^\circ$ by using a narrow-width approximation for the intermediate-state vector mesons. We then perform fits to the $e^+e^-\to π^+π^-$ data base and study the consequences for the two-pion HVP contribution to the anomalous magnetic moment of the muon, its IB part due to $ρ$-$ω$ mixing, and the mass of the $ω$ resonance. We find that the global fit does prefer a non-vanishing value of $δ_ε=4.5(1.2)^\circ$, close to the narrow-resonance expectation, but with a large spread among the data sets, indicating systematic differences in the $ρ$-$ω$ region.
