Relativistic distribution function for particles with spin at local thermodynamical equilibrium

14th Conference on Theoretical Nuclear Physics in Italy

Grossi, E.^1

Università di Firenze, INFN Sezione di Firenze, Florence, Italy^1

关键词: Gradient of temperature;    Interacting particles;    Inverse temperatures;    Local thermodynamical equilibrium;    Particles with spin;    Relativistic heavy ion collision;    Single-particle distribution function;    Spin degrees of freedom;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/527/1/012015/pdf
DOI  :  10.1088/1742-6596/527/1/012015

来源: IOP

【 摘 要 】

We present an extension of relativistic single-particle distribution function for weakly interacting particles at local thermodynamical equilibrium including spin degrees of freedom, for massive spin 1/2 particles. We infer, on the basis of the global equilibrium case, that at local thermodynamical equilibrium particles acquire a net polarization proportional to the vorticity of the inverse temperature four-vector field. The obtained formula for polarization also implies that a steady gradient of temperature entails a polarization orthogonal to particle momentum. The single-particle distribution function in momentum space extends the so-called Cooper-Frye formula to particles with spin 1/2 and allows to predict their polarization, and particularly of Lambda hyperons, in relativistic heavy ion collisions at the freeze-out.