Spin evolution of massive fermion in QED plasma
Ziyue Wang
Abstract
The dynamical evolution of spin of a massive probe fermion in a hot QED plasma at local equilibrium is investigated through the quantum kinetic theory. We consider the massive probe fermion undergoing 2-by-2 Coulomb scattering with the massless fermions in the medium. The axial kinetic equation is derived including the collision terms to the first order of gradients and leading logarithmic order of the coupling. The collision terms are vanishing at global equilibrium, around which the relaxation time can be extracted as an operator. We further decompose the axial kinetic equation into kinetic equations of axial-charge density as well as the transverse magnetic dipole moment. The polarization rate and diffusion rate are estimated in massless limit and nonrelativistic limit, between both limit, polarization and diffusion effects are illustrated through preliminary numerical analysis.