Yang Yi-Bo, Sufian Raza Sabbir, Alexandru Andrei, Draper Terrence, Glatzmaier Michael J, Liu Keh-Fei, Zhao Yong
Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA.
Department of Physics, The George Washington University, Washington, D.C. 20052, USA.
Phys Rev Lett. 2017 Mar 10;118(10):102001. doi: 10.1103/PhysRevLett.118.102001. Epub 2017 Mar 6.
We report the first lattice QCD calculation of the glue spin in the nucleon. The lattice calculation is carried out with valence overlap fermions on 2+1 flavor domain-wall fermion gauge configurations on four lattice spacings and four volumes including an ensemble with physical values for the quark masses. The glue spin S_{G} in the Coulomb gauge in the modified minimal subtraction (MS[over ¯]) scheme is obtained with one-loop perturbative matching. We find the results fairly insensitive to lattice spacing and quark masses. We also find that the proton momentum dependence of S_{G} in the range 0≤|p[over →]|<1.5 GeV is very mild, and we determine it in the large-momentum limit to be S_{G}=0.251(47)(16) at the physical pion mass in the MS[over ¯] scheme at μ^{2}=10 GeV^{2}. If the matching procedure in large-momentum effective theory is neglected, S_{G} is equal to the glue helicity measured in high-energy scattering experiments.
我们报告了对核子中胶子自旋的首次格点量子色动力学计算。该格点计算是在具有2 + 1味的畴壁费米子规范构型上，使用价重叠费米子进行的，涉及四个格点间距和四个体积，其中包括一个具有夸克质量物理值的系综。在修正的最小减法（MS[上划线]）方案中，通过单圈微扰匹配得到库仑规范下的胶子自旋(S_{G})。我们发现结果对格点间距和夸克质量相当不敏感。我们还发现，在(0\leq|\vec{p}|\lt1.5) GeV范围内，(S_{G})对质子动量的依赖性非常微弱，并且在大动量极限下，我们确定在(\mu^{2}=10) GeV²的MS[上划线]方案中，物理π介子质量下(S_{G}=0.251(47)(16))。如果忽略大动量有效理论中的匹配过程，(S_{G})等于在高能散射实验中测量的胶子螺旋度。
