论QCD中4阶劈裂函数的状态
On the status of the 4-loop splitting functions in QCD
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中文总结 AI 辅助
本文简述QCD四阶劈裂函数最新结果：非单态完全已知，单态含新解析结构，数值效应在基准点约1%或更小，总价夸克分布除外。
中文摘要 AI 辅助
我们简要讨论了强子部分子分布尺度依赖性中四阶劈裂函数的最新结果。三个非单态情况现已完全已知。这些结果与几乎所有预期相符，但表现出低阶未遇到的小x双对数。味单态情况包括，从目前的偏结果中已明显看出，迄今在劈裂函数中未见到的解析结构。四阶贡献对尺度导数的数值效应（及其在单态情况中的不确定性）在标准基准点（α_s=0.2）下，对于动量分数x低至约10^{-4}时，约为1%或更小，但总价夸克分布除外。
英文摘要
We briefly discuss recent results on the four-loop splitting functions for the scale dependence of the parton distributions of hadrons. The three non-singlet cases are now completely known. The results agree with almost all expectations, but exhibit some small-$x$ double logarithms not encountered at lower orders. The flavour-singlet cases include, as already obvious from the present partial results, analytical structures not seen in the splitting functions up to now. The numerical effects (and their uncertainties, in the singlet cases) of the four-loop contributions to the scale derivatives amount to about $1\%$ or less down to momentum fractions $x$ as low as about $10^{-4}$ at a standard benchmark point with $α_{\rm s} = 0.2$, with the exception of the total valence quark distribution.
发表机构
- Hamburg University（汉堡大学）
- University of Liverpool（利物浦大学）
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