Lattice QCD calculations of nucleon form factors are restricted to discrete values of the Euclidean four-momentum transfer. Therefore, the extraction of radii typically relies on parametrizing and fitting the lattice QCD data to obtain its slope close to zero momentum transfer. We investigate a new method, which allows to compute the nucleon radius directly from existing lattice QCD data, without assuming a functional form for the momentum dependence of the underlying form factor. The method is illustrated for the case of the isovector mean-square charge radius of the nucleon ? r isov 2 ? and the quark-connected contributions to ? r p 2 ? and ? r n 2 ? for the proton and neutron, respectively. Computations are performed using a single gauge ensemble with N f = 2 + 1 + 1 maximally twisted mass clover-improved fermions at physical quark mass and a lattice spacing of a = 0.08 ? ? fm .
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机译：核心QCD核心形式因子的QCD计算被限制为欧几里德四势转移的离散值。 因此，RADII的提取通常依赖于参数化和装配晶格QCD数据，以获得其倾斜接近于零动量转移。 我们研究了一种新方法，该方法允许直接从现有的晶格QCD数据计算核子半径，而不假设潜在形状因子的动量依赖性的功能形式。 该方法示出了核心的等管平均电荷半径的情况下的情况？ r isov 2？ 和夸克相关的贡献？ r p 2？ 和 ？ r n 2？ 对于质子和中子。 在物理夸克质量和A = 0.08的晶格间距，使用单个仪表集合使用N F = 2 + 1 + 1 + 1的最大扭曲的质量三叶草改进的费用米来执行计算。 还 FM。
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