实光子的新部分子分布函数
New parton distribution functions of the real photon
AI总结：
本文通过全局QCD分析正负电子对撞中实光子靶的深度非弹性散射数据，确定了实光子新的领头阶和次领头阶部分子分布函数VALO1.0，提供了蒙特卡洛不确定度并开发了开源框架。
AI中文摘要：
鉴于在大型强子对撞机（LHC）的超外围碰撞（UPCs）和未来的电子-离子对撞机（EIC）中正在进行的高能光子诱导过程的研究，精确确定实光子的部分子结构重新引起了人们的兴趣。尽管光子中的夸克和胶子分布本身是基础性的，并且对于由解析光子引发的硬过程的QCD唯象学至关重要，但人们对它们的了解甚少，值得采用现代统计数据分析工具进行新的分析。我们通过对世界范围内在正负电子对撞中实光子靶上的深度非弹性散射（DIS）过程中测得的光子结构函数$F_2^{\gamma}$的数据进行全局QCD分析，确定了实光子的新一组领头阶（LO）和次领头阶（NLO）部分子分布（PDFs），命名为VALO1.0。我们的分析通过提供蒙特卡洛副本形式的不确定性和LHAPDF6格式的光子PDFs，改进了文献中已有的结果。我们观察到，虽然正负电子数据使我们能够在LO和NLO下都非常好地确定单态夸克分布，但胶子分布受到的限制程度要小得多，尤其是在LO下。为了这次分析，我们开发了一个开源框架，该框架扩展了为质子开发的pineline框架到光子情形，并包含了求解光子PDFs非均匀标度演化的程序$\gamma$EKO。
英文摘要：
Precise determination of the partonic structure of real photons has attracted renewed interest in view of ongoing studies of high-energy photon-induced processes in ultraperipheral collisions (UPCs) at the Large Hadron Collider (LHC) and the future Electron-Ion Collider (EIC). Despite being fundamental in their own right and essential for QCD phenomenology of hard processes initiated by resolved photons, the quark and gluon distributions of the photon are poorly known and merit a new analysis employing modern tools of statistical data analysis. We determine new sets of leading-order (LO) and next-to-leading-order (NLO) parton distributions (PDFs) for the real photon, dubbed VALO1.0, by performing a global QCD analysis of the world data on the photon structure function $F_2^γ$ measured in deep-inelastic scattering (DIS) processes on a real photon target in electron-positron collisions. Our analysis improves on the results available in the literature by providing uncertainties in the form of Monte Carlo replicas and the photon PDFs in the LHAPDF6 format. We observe that while the electron-positron data allow us to determine the singlet quark distribution very well at both LO and NLO, the gluon distribution is constrained to a much lesser degree, especially at LO. For this analysis, we have developed an open-source framework, which extends the pineline framework, developed for the proton, to the photon case and includes the program solving the inhomogeneous scale evolution of photon PDFs, $γ$EKO.
