标题： 具有动力夸克的格林函数中$α_s$的初步计算 显示英文标题

标题： Preliminary Calculation of $α_s$ from Green Functions with Dynamical Quarks

摘要： 我们展示了在计算QCD动态Wilson夸克的运行耦合常数时，在$\widetilde{MOM}$方案和Landau规范下的初步结果。胶子动量范围高达大约7GeV ($\beta =$5.6, 5.8 和 6.0)，并且有一个恒定的动力夸克质量。 这个范围已经允许展示出一些证据，表明存在一个显著的$1/\mu^2$修正到渐近行为，就像在淬火近似中一样，尽管没有幂次修正的拟合仍然可以用合理的$\chi^2$来完成。 根据我们的淬火研究的结论，我们考虑了$1/\mu^2$对渐近行为的修正。我们发现$\Lambda_{\rm \bar{MS}}^{N_f=2} = 264(27) {\rm MeV} \times [{a^{-1}(5.6,0.1560)}/{2.19 {\rm GeV}}] $，这导致了$\alpha_s(M_Z) = 0.113(3)(4)$。 鉴于系统误差仍需控制，后者的结果应被视为初步指示而不是真正的预测。然而，由于它比实验结果低两个标准差，这非常令人鼓舞。 显示英文摘要

摘要： We present preliminary results on the computation of the QCD running coupling constant in the $\widetilde{MOM}$ scheme and Landau gauge with two flavours of dynamical Wilson quarks. Gluon momenta range up to about 7 GeV ($\beta =$ 5.6, 5.8 and 6.0) with a constant dynamical-quark mass. This range already allows to exhibit some evidence for a sizable $1/\mu^2$ correction to the asymptotic behaviour, as in the quenched approximation, although a fit without power corrections is still possible with a reasonable $\chi^2$. Following the conclusions of our quenched study, we take into account $1/\mu^2$ correction to the asymptotic behaviour. We find $\Lambda_{\rm \bar{MS}}^{N_f=2} = 264(27) {\rm MeV} \times [{a^{-1}(5.6,0.1560)}/{2.19 {\rm GeV}}] $, which leads to $\alpha_s(M_Z) = 0.113(3)(4)$. The latter result has to be taken as a preliminary indication rather than a real prediction in view of the systematic errors still to be controlled. Still, being two sigmas below the experimental result makes it very encouraging.