Nonperturbative magnetotransport from band geometry in Weyl semimetals

We develop a nonperturbative semiclassical theory of magnetotransport in Weyl semimetals, retaining the full magnetic-field dependence of the Fermi-surface conductivity in the presence of Berry curvature and orbital magnetic moment effects. We obtain closed-form expressions valid to all orders in the magnetic field within the semiclassical regime. We show that the exact continuum formulation exhibits an intrinsic infrared sensitivity associated with the singular behavior of the orbital magnetic moment, requiring a physically motivated regularization. While the full conductivity tensor reduces to the standard quadratic magnetoconductivity, we demonstrate that magnetic-field expansion and momentum integration do not commute, leading to nonanalytic contributions at the level of scalar transport coefficients. Our results identify a regime, relevant for low carrier densities or moderate magnetic fields, where magnetotransport becomes intrinsically nonperturbative and cannot be captured by conventional weak-field expansions.