▎ 摘　　要

We present a robust and exact method for calculating the polarization function and plasmon dispersion of graphene, for an arbitrary (isotropic) nonequilibrium carrier distribution, within the random phase approximation. This is demonstrated for a range of carrier distributions, including hot-carrier distributions which occur within the femtoseconds following photoexcitation. We show that qualitatively different behavior from the equilibrium case can occur. As the polarization function determines dynamic screening, its calculation will be essential to quantifying carrier-carrier scattering channels for graphene far from equilibrium.