The structure of the QED vacuum is a subject of great interest, especially as experiments begin to more directly probe the non-linear regime of the theory. One of the most striking features of the vacuum is its polarization in the presence of an electric field—a non-perturbative phenomenon that leads to pair-production. Detailed information about this non-perturbative structure is contained in the divergence of perturbation theory, which is more generally described by the theory of resurgence. We study the one-loop QED effective action for an exactly solvable, inhomogeneous background field configuration and use Borel summation to illustrate the connection between perturbative and non-perturbative regimes. Using only 10 terms in the weak magnetic field perturbative expansion, we extrapolate to both strong magnetic field and electric field configurations and obtain a pair-production rate which agrees with the exact effective action to remarkable precision.
Nobuyuki Matsumoto