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arXiv 2102.01101hep-phhep-lathep-thnucl-th
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PDF的格点量子色动力学计算中阈值对数的起源与恢复

Origin and Resummation of Threshold Logarithms in the Lattice QCD Calculations of PDFs

Xiang Gao, Kyle Lee, Swagato Mukherjee, Charles Shugert, Yong Zhao

摘要:

现有的许多计算部分子分布函数的格点量子色动力学方法都依赖于某些Euclidean矩阵元在提升强子态中的因式分解公式或有效理论展开。在准PDF和伪PDF方法中,因子分解或展开公式中的匹配系数包括阈值附近的大范围,这是由基础3D动量分布的共线和软发散的微妙相互作用引起的。我们使用标准的处方,恢复这样的mellin矩空间中的对数精度,这也占了DGSTABMM的演变,我们表明,它可以抑制PDF在大$x$。与深度非弹性散射和Drell-Yan截面不同,重算公式远离朗道极点。然后,我们应用我们的配方重新分析最近的晶格结果的π价PDF,并发现,在目前的数据敏感性,阈值重调的影响是边际的可访问的时刻和PDF在大$x$。

英文摘要:

Many present lattice QCD approaches to calculate the parton distribution functions (PDFs) rely on a factorization formula or effective theory expansion of certain Euclidean matrix elements in boosted hadron states. In the quasi- and pseudo-PDF methods, the matching coefficient in the factorization or expansion formula includes large logarithms near the threshold, which arise from the subtle interplay of collinear and soft divergences of an underlying 3D momentum distribution. We use the standard prescription to resum such logarithms in the Mellin-moment space at next-to-leading logarithmic accuracy, which also accounts for the DGLAP evolution, and we show that it can suppress the PDF at large $x$. Unlike the deep inelastic scattering and Drell-Yan cross sections, the resummation formula is away from the Landau pole. We then apply our formulation to reanalyze the recent lattice results for the pion valence PDF, and find that within the current data sensitivity, the effect of threshold resummation is marginal for the accessible moments and the PDF at large $x$.

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