The concept of the Wigner function is used to construct a semi-classical kinetic theory describing the evolution of the axial-current phase-space density of spin-1/2 particles in the relaxation time approximation. The resulting approach can be used to study spin-polarization effects in relativistic matter, in particular, in heavy-ion collisions. An expression for the axial current based on the classical treatment of spin is also introduced and we show that it is consistent with earlier calculations using Wigner functions. Finally, we derive non-equilibrium corrections to the spin tensor, which are used to define, for the first time, the structure of spin transport coefficients in relativistic matter.

中文翻译：

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弛豫时间近似中的相对论耗散自旋动力学

Wigner 函数的概念用于构建描述自旋 1/2 粒子在弛豫时间近似中的轴向电流相空间密度演化的半经典动力学理论。由此产生的方法可用于研究相对论物质中的自旋极化效应，特别是在重离子碰撞中。还引入了基于自旋经典处理的轴向电流表达式，我们表明它与使用 Wigner 函数的早期计算一致。最后，我们推导出自旋张量的非平衡校正，首次用于定义相对论物质中自旋输运系数的结构。