Quantum Electromagnetic Nonlinearity Affecting Charges and Dipole Moments

Abstract

Due to the nonlinearity of QED, a static charge becomes a magnetic dipole if placed in a magnetic field, and a magnetic monopole on the background is a combination of constant electric and magnetic fields. Already without external field, the cubic Maxwell equation for the field of a point charge has a soliton solution with a finite field energy and finite potential, the energy-momentum vector of a moving soliton being the same as that of a point massive particle. Equations are given for self-coupling dipole moments. Any theoretically found value for a multipole moment of a baryon or a meson should be subjected to nonlinear renormalization.