论文标题
中性锥度磁极化的手性外推
Chiral extrapolation of the magnetic polarizability of the neutral pion
论文作者
论文摘要
中性触发的磁极化性已经在晶格QCD的背景磁场形式上计算。在这项研究中，在形式主义中考虑了这些晶格结果的手性外推，该形式主义保留了手性扰动理论的确切领先的未分析术语。 $ n_f = 2 + 1 $数值模拟是电淬火的，因此QCD真空的虚拟海夸克不会与背景字段相互作用。为了了解这一点的影响，我们利用部分淬火的手性扰动理论，并确定夸克 - 流相关图和断开图的主要贡献。虽然电淬火不会影响对磁化性磁性的领先贡献，但在晶格QCD模拟中尚未考虑产生领先术语的回路。晶格QCD结果用于限制手性膨胀中的分析术语，并通过手性扰动理论补充两层循环的人，可以评估物理夸克质量的极化性。中性触发的结果磁极化率为$β_{π^0} = 3.44（19）^{\ rm Stat}（\ rm Stat}（37）^{\ rm syst} \ times 10^{ - 4} $ fm $^3 $，该$ fm $^3 $，仅在$ 1σ$误差限制的实验性测量中。
The magnetic polarizability of the neutral pion has been calculated in the background magnetic-field formalism of Lattice QCD. In this investigation, the chiral extrapolation of these lattice results is considered in a formalism preserving the exact leading nonanalytic terms of chiral perturbation theory. The $n_f = 2 + 1$ numerical simulations are electro-quenched, such that the virtual sea-quarks of the QCD vacuum do not interact with the background field. To understand the impact of this, we draw on partially quenched chiral perturbation theory and identify the leading contributions of quark-flow connected and disconnected diagrams. While electro-quenching does not impact the leading-loop contribution to the magnetic polarizability, the loops which generate the leading term have yet to be considered in lattice QCD simulations. Lattice QCD results are used to constrain the analytic terms in the chiral expansion and supplementing those with the two-loop result from chiral perturbation theory enables an evaluation of the polarizability at the physical quark mass. The resulting magnetic polarizability of the neutral pion is $β_{π^0}=3.44(19)^{\rm stat}(37)^{\rm syst}\times 10^{-4}$ fm$^3$, which lies just above the $1 σ$ error bound of the experimental measurement.
