标题： 从格点QCD到连续极限的π介子纯标量半径 显示英文标题

标题： The scalar radius of the pion from Lattice QCD in the continuum limit

摘要： 我们扩展了关于双味格点QCD中派生标量半径的研究，纳入了两个额外的格点间距以及更轻的派生质量，这使我们能够进行联合的反常和连续极限外推。 我们发现半径的离散化效应很小，并确认了在重现正确的反常行为时，弥散图的重要性。 派生标量半径在物理点上的最终结果为$\left\langle r^2\right\rangle^\pi_{\rm S}=0.600\pm0.052$ fm$^2$，对应于NLO反常微扰理论中低能常数$\overline{\ell}_4$的值为$\overline{\ell}_4=4.54\pm0.30$。 显示英文摘要

摘要： We extend our study of the pion scalar radius in two-flavour lattice QCD to include two additional lattice spacings as well as lighter pion masses, enabling us to perform a combined chiral and continuum extrapolation. We find discretisation artefacts to be small for the radius, and confirm the importance of the disconnected diagrams in reproducing the correct chiral behaviour. Our final result for the scalar radius of the pion at the physical point is $\left\langle r^2\right\rangle^\pi_{\rm S}=0.600\pm0.052$ fm$^2$, corresponding to a value of $\overline{\ell}_4=4.54\pm0.30$ for the low-energy constant $\overline{\ell}_4$ of NLO chiral perturbation theory.