Polarizability and its generalization

Abstract

Traditional and newly developed aspects of polarizability are described from the viewpoint of micro and macroscopic responses, local and non-local behavior, and their roles in electromagnetic (EM) responses. A generalization of polarizability is given as a single susceptibility covering electric, magnetic and chiral polarizations for isolated charged particles in transversal and longitudinal external EM fields. It gives the first-principles expression of chiral susceptibility, absent in the literature. The argument is based on the minimal coupling Lagrangian for charged particles in an EM field, and the response is guaranteed to be gauge invariant.