标题： 精确的NNLO修正与PDF拟合中的K因子 显示英文标题

标题： Exact NNLO corrections vs K-factors in PDF fits

摘要： 部分子分布函数（PDFs）通常包括对应于理论预测在微扰QCD中需要近似的下一阶下一阶（NNLO）过程的数据集，这种近似可以使用K因子来完成，而K因子又依赖于用于计算它们的PDF集。在本研究中，我们研究了使用不同PDF集（即CT18、MSHT20和NNPDF4.0）产生的K因子对大型强子对撞机（LHC）上顶对产生（微分）截面的影响。此外，我们进行了一次新的拟合（否则与NNPDF4.0的MHOUs类似），其中在拟合过程中使用了精确的NNLO修正，并将从该拟合中获得的K因子与上述提到的PDF集获得的K因子进行比较。我们发现这些不同PDF集获得的K因子之间有良好的一致性。 显示英文摘要

摘要： Parton distribution functions (PDFs) often include datasets corresponding to processes whereby the theoretical predictions at next-to-next-to-leading order (NNLO) in peturbative QCD have to be approximated, and this approximation may be performed using K-factors, which in turn depend on the PDF set used to compute them. In this study, we investigate the impact of K-factors produced with various PDF sets, namely CT18, MSHT20 and NNPDF4.0 on (differential) cross sections of top pair production at the Large Hadron Collider (LHC). Furthermore, we perform a new fit (otherwise analogous to NNPDF4.0 with MHOUs) where the exact NNLO corrections are used in the fitting procedure and compare the K-factors obtained from this fit with those obtained from the above mentioned PDF sets. We find good agreement amongst K-factors obtained from these different PDF sets.