标题： 通过使用维度正则化中的$γ_5$由局部CPT破坏耦合诱导的有效 Chern-Simons 项 显示英文标题

标题： On effective Chern-Simons Term induced by a Local CPT-Violating Coupling using $γ_5$ in Dimensional Regularization

摘要： 我们重新开始了关于由拉格朗日量中的局部项$b_\mu\bar\psi\gamma^\mu \gamma_5\psi$是否可以产生Chern-Simons双折射的长期争论（其中$b_\mu$是常数）。在本文中，我们采用了一种新的方法来处理维度正则化中的$\gamma_5$。通过这种定义发散幅度的方式，强制执行了底层理论（QED）中的规范不变性。我们研究了矢量介子两点函数在$m^2=0$和$p^2=0$点附近的奇异行为。我们发现有效Chern-Simons的系数可以是有限的或零。这取决于如何取极限：由于对称性的相关变化，这些极限不能互换。对于$m^2=0$，我们还计算了光子在二阶$b_\mu$下的自质量。我们发现结果为零。 显示英文摘要

摘要： We resume a long-standing, yet not forgotten, debate on whether a Chern-Simons birefringence can be generated by a local term $b_\mu\bar\psi\gamma^\mu \gamma_5\psi$ in the Lagrangian (where $b_\mu$ are constants). In the present paper we implement a new way of managing $\gamma_5$ in dimensional regularization. Gauge invariance in the underlying theory (QED) is enforced by this choice of defining divergent amplitudes. We investigate the singular behavior of the vector meson two-point-function around the $m^2=0$ and $p^2=0$ point. We find that the coefficient of the effective Chern-Simons can be finite or zero. It depends on how one takes the limits: they cannot be interchanged due to the associate change of symmetry. For $m^2=0$ we evaluate also the self-mass of the photon at the second orderin $b_\mu$. We find zero.