Quantifying the interplay of experimental constraints in analyses of parton distributions
Quantifying the interplay of experimental constraints in analyses of parton distributions
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DOI：
10.1103/physrevd.108.034029
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发表时间：
2023-06
影响因子：
5
通讯作者：
X. Jing;A. Cooper-Sarkar;A. Courtoy;T. Cridge;F. Giuli;L. Harland–Lang;T. Hobbs;J. Huston;P. Nadolsky;R. Thorne;K. Xie;C. Yuan
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文献类型：
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作者：
X. Jing;A. Cooper-Sarkar;A. Courtoy;T. Cridge;F. Giuli;L. Harland–Lang;T. Hobbs;J. Huston;P. Nadolsky;R. Thorne;K. Xie;C. Yuan
在大型强子对撞机（LHC）的计算中，部分子分布函数（pdf）起着核心作用。为了更深入地了解全球QCD分析中PDF的出现和相互作用，重要的是检查PDF拟合中包含的实验数据集的相对重要性和相互兼容性。为了实现这一目标，我们讨论了L2灵敏度，这是一个方便的统计指标，用于探索最佳拟合pdf上单个数据集的统计拉力，并识别竞争数据集之间的紧张关系。与拉格朗日乘数法不同，L2灵敏度可以使用已发布的Hessian误差集快速计算pdf和动量分数的范围。我们采用L2灵敏度作为通用度量来研究最近ATLAS、CTEQ-TEA、MSHT和NNLO和近似N3LO的减少PDF4LHC21 PDF分析中数据集的相对重要性。我们说明了这种方法如何帮助PDF的用户在给定的运动学点上识别对PDF重要的数据集，研究PDF的夸克风味组成和其他详细特征，并比较PDF上各种微扰阶和函数形式的数据拉。我们还讨论了利用蒙特卡罗误差pdf计算灵敏度的可行性。与这篇文章一起，我们提供了一个配套的互动网站，其中包含了8个最近发布的PDF版本的大量L2灵敏度图。
Parton distribution functions (PDFs) play a central role in calculations for the Large Hadron Collider (LHC). To gain a deeper understanding of the emergence and interplay of constraints on the PDFs in the global QCD analyses, it is important to examine the relative significance and mutual compatibility of the experimental data sets included in the PDF fits. Toward this goal, we discuss the L2 sensitivity, a convenient statistical indicator for exploring the statistical pulls of individual data sets on the best-fit PDFs and identifying tensions between competing data sets. Unlike the Lagrange Multiplier method, the L2 sensitivity can be quickly computed for a range of PDFs and momentum fractions using the published Hessian error sets. We employ the L2 sensitivity as a common metric to study the relative importance of data sets in the recent ATLAS, CTEQ-TEA, MSHT, and reduced PDF4LHC21 PDF analyses at NNLO and approximate N3LO. We illustrate how this method can aid the users of PDFs to identify data sets that are important for a PDF at a given kinematic point, to study quark flavor composition and other detailed features of the PDFs, and to compare the data pulls on the PDFs for various perturbative orders and functional forms. We also address the feasibility of computing the sensitivities using Monte Carlo error PDFs. Together with the article, we present a companion interactive website with a large collection of plotted L2 sensitivities for eight recent PDF releases.