论文标题
迈向精确的撞机预测：Parton分支方法
Towards precise collider predictions: the Parton Branching method
论文作者
论文摘要
共线分解定理与扰动QCD中的有限级计算相结合，提供了一个强大的框架，以获取许多对撞机可观察物的预测。但是，对于涉及多个能量尺度的可观察物，不能忽略横向自由度，并且必须将有限级的扰动计算与QCD耦合中所有顺序的所有顺序计算相结合，以获得可靠的理论预测，能够描述实验测量。传统上，这是通过分析调整方法或Parton Shower（PS）Monte Carlo（MC）方法来完成的。在本次演讲中，我们介绍了基于横向动量依赖性（TMD）分解的Parton分支（PB）MC方法，以获得QCD碰撞器预测。 PB提供了TMD Parton分布函数（PDF）的演化方程，将TMD PDF拟合到实验数据后，可以在TMD MC事件生成器中使用。我们介绍了该方法的基本概念，并说明了其在不同运动学范围（从固定目标到LHC能量）中的Drell-Yan（DY）Lepton Pair生产的对撞机测量的应用。我们讨论了该方法的最新发展，尤其是在NLO矩阵元素的MC-AT-NLO计算中，尤其是在将近代阶（NLO）TMD演变匹配的匹配上。
The collinear factorization theorem, combined with finite-order calculations in perturbative QCD, provides a powerful framework to obtain predictions for many collider observables. However, for observables which involve multiple energy scales, transverse degrees of freedom cannot be neglected, and finite-order perturbative calculations have to be combined with resummed calculations to all orders in the QCD running coupling in order to obtain reliable theoretical predictions, capable of describing experimental measurements. This is traditionally done either by analytic resummation methods or by parton shower (PS) Monte Carlo (MC) methods. In this talk we present the Parton Branching (PB) MC method to obtain QCD collider predictions based on Transverse Momentum Dependent (TMD) factorization. The PB provides evolution equations for TMD Parton Distribution Functions (PDFs) which, upon fitting TMD PDFs to experimental data, can be used in TMD MC event generators. We present the basic concepts of the method and illustrate its applications to collider measurements focusing on Drell-Yan (DY) lepton-pair production in different kinematic ranges, from fixed-target to LHC energies. We discuss the latest developments of the method concentrating especially on the matching of next-to-leading-order (NLO) TMD evolution with MC-at-NLO calculations of NLO matrix elements.
