标题： 核子电荷和格点QCD中的$σ$项 显示英文标题

标题： Nucleon charges and $σ$-terms in lattice QCD

摘要： 我们使用扭曲质量费米子确定核子的轴矢电荷、标量电荷和张量电荷以及核子$\sigma$-项。 我们采用三个物理体积约为5.5~fm的集合，三种格点间距，大约为0.06~fm、0.07~fm和0.08~fm，并且简并的上夸克和下夸克、奇异夸克和魅夸克的质量调整到大约其物理值。 我们计算了矢量同位旋和标量同位旋电荷以及$\sigma$-项及其味分解，包括不连接贡献。 我们使用Akaike信息准则来评估由于激发态和连续极限外推带来的系统误差。 对于核子矢量同位旋轴矢电荷，我们得到$g_A^{u-d}=1.250(24)$，与实验值一致。 此外，我们提取了核子$\sigma$-项，并发现轻夸克含量为$\sigma_{\pi N}=41.9(8.1)$~MeV，奇异夸克为$\sigma_{s}=30(17)$~MeV。 显示英文摘要

摘要： We determine the nucleon axial, scalar and tensor charges and the nucleon $\sigma$-terms using twisted mass fermions. We employ three ensembles with approximately equal physical volume of about 5.5~fm, three values of the lattice spacing, approximately 0.06~fm, 0.07~fm and 0.08~fm, and with the mass of the degenerate up and down, strange and charm quarks tuned to approximately their physical values. We compute both isovector and isoscalar charges and $\sigma$-terms and their flavor decomposition including the disconnected contributions. We use the Akaike Information Criterion to evaluate systematic errors due to excited states and the continuum extrapolation. For the nucleon isovector axial charge we find $g_A^{u-d}=1.250(24)$, in agreement with the experimental value. Moreover, we extract the nucleon $\sigma$-terms and find for the light quark content $\sigma_{\pi N}=41.9(8.1)$~MeV and for the strange $\sigma_{s}=30(17)$~MeV.