QCD evolution at one percent precision

质子的分子含量是用普适分子分布函数来参数化的，普适分子分布函数的尺度依赖性由量子色动力学中的演化方程通过分裂函数来控制。在微扰QCD中，分裂函数是可计算的，该项目旨在以四环精度计算它们。这一信息将把QCD演化的理论不确定性降低到百分之一的水平，并且为了与大型强子对撞机的现有实验数据和世界深度非弹性散射（DIS）数据的精度相匹配，这是必要的。该项目旨在朝着完成强子对撞机硬散射反应的次-次-次-次-领先顺序（N3LO） QCD描述迈出决定性的一步。该结果将用于从N3LO精度的世界DIS数据中确定强耦合常数，理论不确定性小于1%。

The proton’s parton content is parameterized in terms of universal parton distribution functions whose scale dependence is governed by the evolution equations in Quantum Chromodynamics (QCD) through the splitting functions. Splitting functions are calculable within perturbative QCD and the project aims at computing them at four-loop accuracy. This information will reduce the theoretical uncertainty in the QCD evolution to the one percent level and it is necessary in order to match the precision of the available experimental data from the Large Hadron Collider and the world data on deep-inelastic scattering (DIS). The project aims at making a decisive step towards completing the next-to-next-to-next-to-leading order (N3LO) QCD description of hard scattering reactions at hadron colliders. The results will be used to determine the strong coupling constant from the world DIS data at N3LO accuracy with a theoretical uncertainty of less than one percent.