$\gamma_5$ in Dimensional Regularization

by Prof. Chen Long (Shandong University)

Monday 8 May 2023, 14:00 → 16:00 Asia/Shanghai

B105 (CHEP)

Calculating correctly the high-order perturbative corrections to quantities involving an axial-current operator in dimension regularization (DR) is non-trivial due to the well-known $\gamma_5$ issue in D dimensions. In this talk I will review a few practical mainstream prescriptions that have been successfully applied in many high-order perturbative calculations, and discuss their advantages and disadvantages both from the technical side and the conceptual side. 
In particular, the talk will be focusing on the renormalization of the flavor-singlet axial-current operator defined with a non-anticommuting $\gamma_5$ in dimensional regularization up to $\mathcal{O}(\alpha_s^5)$ in QCD.
I highlight also a recent observation of a subtle issue encountered in applying a Kreimer-scheme variant (with an anticommuting $\gamma_5$) to the calculations of Feynman diagrams with axial anomalous subgraphs, as well as its amendment.
To make contact with practical physical applications, I will discuss, as an example, the resummation of the so-called non-decoupling mass logarithms in the axial quark form factors, closely related to the non-anomalous dimension of a singlet axial-current operator resulting from its non-trivial renormalization.

个人简介：
陈龙，2017年在德国亚琛工业大学获得理学博士学位，随后到马克斯普朗克理论物理所等机构进行博士后研究。自2022年入职山东大学物理学院。主要研究领域为粒子物理理论，着重于将微扰量子场论方法应用于精确研究高能对撞机上粒子间的散射行为。主要研究方向包括正负电子对撞机上的重夸克对产生，重夸克和希格斯玻色子的微分衰变截面，维数正规化下散射振幅投影算符的构造以及手征矩阵的处理、轴矢流算符的重整化，LHC上若干中性玻色子产生过程的高阶微扰修正等。

Tencent Meeting: 232-639-307