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arXiv 1107.0338hep-phhep-th
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在QCD中设置重整化标度:最大共形性原理

Setting the Renormalization Scale in QCD: The Principle of Maximum Conformality

Stanley J. Brodsky, Leonardo Di Giustino

摘要:

精确微扰QCD预言的一个关键问题是确定运行耦合$α_s(μ^2).$的重正化标度$μ$的不确定性。运行耦合在任何规范理论中的目的是求和所有涉及$β$函数的项;事实上,当重正化标度设置正确时,所有由重正化引起的微扰展开中的非共形$β\ne 0$项都被求和到运行耦合中。微扰级数中的其余项则与共形理论中的项相同;即,与$β=0$的对应理论。使用“最大共形性原理”(PMC)得到的尺度固定预测与重整化方案的选择无关--这是重整化群不变性的关键要求。结果避免了重正马龙的重正化,并与阿贝尔极限下的QED标度设置相一致。PMC也是BLM过程、可观测量之间的公度标度关系和格点规范理论中使用的标度设定方法的理论基础。QCD $β$函数中的活性风味$n_f$的数量也被正确地确定。本文讨论了几种确定QCD过程PMC标度的方法。我们表明,一个单一的全球PMC规模,有效的领导阶,可以从微扰QCD截面的基本性质。使用PMC消除重整化标度模糊性和方案依赖性不仅将提高QCD测试的精度,而且还将提高对撞机实验对标准模型之外的新物理的敏感性。

英文摘要:

A key problem in making precise perturbative QCD predictions is the uncertainty in determining the renormalization scale $μ$ of the running coupling $α_s(μ^2).$ The purpose of the running coupling in any gauge theory is to sum all terms involving the $β$ function; in fact, when the renormalization scale is set properly, all non-conformal $β\ne 0$ terms in a perturbative expansion arising from renormalization are summed into the running coupling. The remaining terms in the perturbative series are then identical to that of a conformal theory; i.e., the corresponding theory with $β=0$. The resulting scale-fixed predictions using the "principle of maximum conformality" (PMC) are independent of the choice of renormalization scheme -- a key requirement of renormalization group invariance. The results avoid renormalon resummation and agree with QED scale-setting in the Abelian limit. The PMC is also the theoretical principle underlying the BLM procedure, commensurate scale relations between observables, and the scale-setting method used in lattice gauge theory. The number of active flavors $n_f$ in the QCD $β$ function is also correctly determined. We discuss several methods for determining the PMC scale for QCD processes. We show that a single global PMC scale, valid at leading order, can be derived from basic properties of the perturbative QCD cross section. The elimination of the renormalization scale ambiguity and the scheme dependence using the PMC will not only increase the precision of QCD tests, but it will also increase the sensitivity of collider experiments to new physics beyond the Standard Model.

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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