arXiv 1004.46242010-04hep-ph

部分子分布CTEQ整体分析中QCD耦合引起的不确定性

Uncertainty induced by QCD coupling in the CTEQ global analysis of parton distributions

Hung-Liang Lai, Joey Huston, Zhao Li, Pavel Nadolsky, Jon Pumplin, Daniel Stump, C. -P. Yuan

备注：: minor changes for publication
发表信息：: Phys.Rev.D82:054021,2010
DOI：: 10.1103/PhysRevD.82.054021

摘要：

研究了部分子分布函数对QCD耦合强度$α_{s}(M_{Z})$的依赖性。我们解释了一个简单的方法，是严格有效的二次近似通常应用在PDF拟合，并充分再现相关的依赖关系的理论截面上$α_s$和PDF参数。该方法基于一种统计关系，该统计关系允许将由$α_s$产生的不确定性与固定$α_s$值（例如CTEQ6.6 PDF集）获得的PDF不确定性正交相加，该不确定性是使用某些特殊PDF集计算的。一系列的四个CTEQ6.6AS PDF实现这种方法，为$α_s$值的间隔$0.116 \leq α_{s}(M_{Z}) \leq 0.120$，提出。使用这些PDF，结合$α_{s}$和PDF的不确定性进行评估，在费米实验室Tevatron和大型强子对撞机的理论预测。

英文摘要：

We examine the dependence of parton distribution functions (PDFs) on the value of the QCD coupling strength $α_{s}(M_{Z})$. We explain a simple method that is rigorously valid in the quadratic approximation normally applied in PDF fitting, and fully reproduces the correlated dependence of theoretical cross sections on $α_s$ and PDF parameters. This method is based on a statistical relation that allows one to add the uncertainty produced by $α_s$, computed with some special PDF sets, in quadrature with the PDF uncertainty obtained for the fixed $α_s$ value (such as the CTEQ6.6 PDF set). A series of four CTEQ6.6AS PDFs realizing this approach, for $α_s$ values in the interval $0.116 \leq α_{s}(M_{Z}) \leq 0.120$, is presented. Using these PDFs, the combined $α_{s}$ and PDF uncertainty is assessed for theoretical predictions at the Fermilab Tevatron and Large Hadron Collider.

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