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arXiv 0910.3101hep-ph
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NNLO上重味对F_2(x,Q^2)贡献的Mellin矩

Mellin moments of heavy flavor contributions to F_2(x,Q^2) at NNLO

Sebastian Klein

摘要:

本文研究了结构函数F_2(x,Q_2)的Wilson系数在极限Q_2>> m_2下的O(a_s^3)重味贡献的固定矩的计算,忽略了幂修正。渐近区域中的质量Wilson系数被给出为质量算子矩阵元(OME)和已知的轻味Wilson系数的卷积。前者来自于光锥展开中出现的扭曲2算子,并在固定矩的3圈水平上计算。我们还计算了大量的OME,这是需要评估重味部分子分布的可变味数计划,以相同的顺序。除了OME在O(a_s^3)处的真正常数项之外,所有对威尔逊系数和OME的贡献都是用量来表示的,这些量对于梅林变量N的一般值是已知的。对于OME A_{Qg} ^(3)、A_{qg,Q} ^(3)和A_{gg,Q} ^(3),计算矩N = 2至10,对于A_{Qq} ^{(3),PS}至N = 12,以及对于A_{qq,Q} ^{(3),NS}、A_{qq,Q} ^{(3),PS}、A_{gq,Q} ^(3)}至N=14。这些术语有助于清淡风味“+”组合。对于风味非单态项,我们还计算了奇数矩N=1至13,对应于轻风味组合。在独立的计算中,我们还得到了三圈反常维数T_F项的矩,与文献中的结果一致。的数学结构发生的动量积分和谐波和的最终结果进行了讨论。我们也研究了在非线性光学和非线性光学水平上同样的技术在极化和横向情况下的应用。

英文摘要:

This thesis is concerned with the calculation of fixed moments of the O(a_s^3) heavy flavor contributions to the Wilson coefficients of the structure function F_2(x,Q^2) in the limit Q^2 >> m^2, neglecting power corrections. The massive Wilson coefficients in the asymptotic region are given as convolutions of massive operator matrix elements (OMEs) and the known light flavor Wilson coefficients. The former derive from the twist--2 operators emerging in the light--cone--expansion and are calculated at the 3--loop level for fixed moments. We also compute the massive OMEs which are needed to evaluate heavy flavor parton distributions in the variable flavor number scheme to the same order. All contributions to the Wilson coefficients and OMEs but the genuine constant terms at O(a_s^3) of the OMEs are derived in terms of quantities, which are known for general values in the Mellin variable N. For the OMEs A_{Qg}^(3), A_{qg,Q}^(3) and A_{gg,Q}^(3) the moments N = 2 to 10, for A_{Qq}^{(3), PS} to N = 12, and for A_{qq,Q}^{(3), NS}, A_{qq,Q}^{(3), PS}, A_{gq,Q}^(3)}to N=14 are computed. These terms contribute to the light flavor '+'-combinations. For the flavor non-singlet terms, we calculate as well the odd moments N=1 to 13, corresponding to the light flavor '-'-combinations. We also obtain moments of the terms ~ T_F of the 3-loop anomalous dimensions in an independent calculation, which agree with results given in the literature. The mathematical structure of the occurring momentum integrals and of the final results in terms of harmonic sums is discussed. We study applications of the same techniques to the polarized and transversity case at the NLO and NNLO level as well.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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