标题： 一种改进的Wigner函数和自旋极化公式在局部热平衡的解耦相对论流体中 显示英文标题

标题： An improved formula for Wigner function and spin polarization in a decoupling relativistic fluid at local thermodynamic equilibrium

摘要： 我们提出了一种改进的Wigner函数和费米子在退耦时由相对论流体在局部热平衡下发射的自旋极化公式，该公式优于参考文献[1, 2]中得到的公式，并用于相对论核碰撞的数值模拟。通过使用一种新的展开方法，适用于任意几何结构的退耦超曲面，我们重现了与热涡度成比例的已知项，并得到了一个改进的自旋-剪切项，该术语捕捉了几何依赖性。新方法还包括一些额外贡献，其物理性质有待评估。新表达式自然排除了超曲面法向方向上的时空梯度贡献，为之前先验施加的等温条件提供了理论依据。此框架可以扩展到任意自旋的粒子。 显示英文摘要

摘要： We present an upgraded formula for Wigner function and spin polarization of fermions emitted by a relativistic fluid at local thermodynamic equilibrium at the decoupling which improves the one obtained in refs. [1, 2] and used in numerical simulations of relativistic nuclear collisions. By using a new expansion method, applicable to decoupling hypersurfaces with arbitrary geometry, we reproduce the known term proportional to thermal vorticity and obtain an upgraded form of the spin-shear term which captures the dependence on the geometry. The new method also includes additional contributions whose physical nature is to be assessed. The new expression also naturally excludes contributions from space-time gradients in the normal direction of the hypersurface, providing a theoretical justification for the isothermal condition previously imposed a priori. This framework can be extended to particles with arbitrary spin.