Toward a bottom-up formulation of spin kinetic theory
Phys. Rev. D 114, 034014 – Published 11 August, 2026
DOI: https://doi.org/10.1103/jy99-lhg8
Abstract
We develop a bottom-up formulation of spin-kinetic theory for hot and/or dense plasmas relevant for matter created in a heavy-ion collision. We introduce scalar and axial-vector phase-space functions as dynamical variables that parametrize both spin-averaged and spin-dependent distribution functions. Using spin-dependent Poisson brackets, we derive the corresponding kinetic equations and construct the associated Schwinger-Keldysh action. We further demonstrate how physical observables can be expressed in terms of these dynamical variables through constitutive relations. In the linear response regime, we establish a precise matching between the kinetic-theory and field-theory descriptions of vector and axial Wigner functions under electromagnetic and gravitational perturbations. Our framework provides a complementary approach to describing the dynamics of spin effects in a medium.
