We studied the $m=0$ limit of different components of Wigner functions for massive fermions. Comparing with the chiral kinetic theory, we separated the vanishing part and non-vanishing part for vector and axial vector components, up to the first order of $\hbar$. Then we discussed the possible physical meaning of the vanishing and non-vanishing parts, and their different behavior at thermal equilibrium.

中文翻译：

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大质量费米子传输理论的无质量极限

我们研究了大规模费米子的 Wigner 函数不同分量的 $m=0$ 极限。与手性动力学理论相比，我们将矢量和轴矢量分量的消失部分和非消失部分分开，直到 $\hbar$ 的一阶。然后我们讨论了消失和非消失部分可能的物理意义，以及它们在热平衡时的不同行为。