Parton distributions with theory uncertainties: general formalism and first phenomenological studies NNPDF Collaboration
Parton distributions with theory uncertainties: general formalism and first phenomenological studies NNPDF Collaboration
复制标题
具有理论不确定性的帕顿分布：一般形式主义和第一个现象学研究 NNPDF 协作
DOI：
10.1140/epjc/s10052-019-7401-4
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Abdul Khalek R
中科院分区：
文献类型：
--
作者：
Abdul Khalek R
我们制定了一个一般的方法，包括理论的不确定性，特别是那些失踪的高阶不确定性（MHOU），在部分子分布函数（PDF）的确定。我们演示了如何在相当通用的假设下，理论不确定性可以作为协方差矩阵的额外贡献，从数据中确定PDF时。然后，我们审查，澄清，并系统化使用重整化和因式分解尺度变化作为一种手段，以估计MHOU始终在深非弹性和强子过程。我们定义了一组处方，用于使用尺度变化构建理论协方差矩阵，该理论协方差矩阵可用于来自各种不同过程的数据的全局拟合，基于选择一组独立的尺度变化，这些尺度变化在过程内和过程之间适当相关。我们建立了一个代数框架的选择和验证的最佳处方，通过比较估计的MHOU编码的次领先阶（NLO）理论协方差矩阵观察到的NLO和NNLO预测之间的变化。我们执行一个NLO PDF的确定，其中包括MHOU，评估包括MHOU的PDF中心值和不确定性的影响，并通过比较NLO和NNLO PDF之间的已知移位来验证结果。最后，我们研究的影响，包括MHOU在一个全球的PDF确定LHC横截面，并提供指导方针，为他们使用的精密唯象学。此外，我们还比较了基于理论协方差矩阵形式主义的结果，通过执行PDF确定基于不同的尺度选择。
We formulate a general approach to the inclusion of theoretical uncertainties, specifically those related to the missing higher order uncertainty (MHOU), in the determination of parton distribution functions (PDFs). We demonstrate how, under quite generic assumptions, theory uncertainties can be included as an extra contribution to the covariance matrix when determining PDFs from data. We then review, clarify, and systematize the use of renormalization and factorization scale variations as a means to estimate MHOUs consistently in deep inelastic and hadronic processes. We define a set of prescriptions for constructing a theory covariance matrix using scale variations, which can be used in global fits of data from a wide range of different processes, based on choosing a set of independent scale variations suitably correlated within and across processes. We set up an algebraic framework for the choice and validation of an optimal prescription by comparing the estimate of MHOU encoded in the next-to-leading order (NLO) theory covariance matrix to the observed shifts between NLO and NNLO predictions. We perform a NLO PDF determination which includes the MHOU, assess the impact of the inclusion of MHOUs on the PDF central values and uncertainties, and validate the results by comparison to the known shift between NLO and NNLO PDFs. We finally study the impact of the inclusion of MHOUs in a global PDF determination on LHC cross-sections, and provide guidelines for their use in precision phenomenology. In addition, we also compare the results based on the theory covariance matrix formalism to those obtained by performing PDF determinations based on different scale choices.