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arXiv 1004.4613hep-phhep-lat
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RI/SMOM方案中轻夸克质量的双圈匹配因子和三圈质量反常维数

Two-loop matching factors for light quark masses and three-loop mass anomalous dimensions in the RI/SMOM schemes

Leandro G. Almeida, Christian Sturm

摘要:

轻夸克的质量可以通过正则化不变动量减法(RI/Momentum-subtraction,RI/Momentum-subtraction)的格点模拟来确定。随后,匹配因子,计算在连续扰动理论,被用来转换这些夸克质量从RI/RI计划MS-酒吧计划。我们计算了这些匹配因子在量子色动力学(QCD)中的双圈修正,以及RI/Scrubber和RI/Scrubber_gamma_mu方案的三圈质量反常维数。这两个方案的特点是一个对称的减法点。在两种不同的方案中提供转换因子可以更好地理解系统的不确定性。两种方案的匹配因子的双环展开系数都比传统的RI/TRI方案小。对于nf=3夸克味,它们分别约为2GeV标度下首阶结果的0.6-0.7%和2%。因此,它们将大大降低通过这种方法获得的轻夸克质量测定的系统不确定性。这些匹配因子的确定需要计算截断的格林函数与夸克双线性算子的插入。作为我们计算的副产品,我们也提供了相应的张量算子的结果。

英文摘要:

Light quark masses can be determined through lattice simulations in regularization invariant momentum-subtraction(RI/MOM) schemes. Subsequently, matching factors, computed in continuum perturbation theory, are used in order to convert these quark masses from a RI/MOM scheme to the MS-bar scheme. We calculate the two-loop corrections in quantum chromodynamics(QCD) to these matching factors as well as the three-loop mass anomalous dimensions for the RI/SMOM and RI/SMOM_gamma_mu schemes. These two schemes are characterized by a symmetric subtraction point. Providing the conversion factors in the two different schemes allows for a better understanding of the systematic uncertainties. The two-loop expansion coefficients of the matching factors for both schemes turn out to be small compared to the traditional RI/MOM schemes. For nf=3 quark flavors they are about 0.6-0.7% and 2%, respectively, of the leading order result at scales of about 2 GeV. Therefore, they will allow for a significant reduction of the systematic uncertainty of light quark mass determinations obtained through this approach. The determination of these matching factors requires the computation of amputated Green's functions with the insertions of quark bilinear operators. As a by-product of our calculation we also provide the corresponding results for the tensor operator.

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