High Energy Physics Seminars

The imaginary part of the QED effective action can be approximated by the contribution of a worldline instanton, a solution to the classical Euclidean worldline equations of motion. In this talk, I will briefly review this formalism and compute also the prefactor arising from quantum fluctuations about this classical path. I will show the excellent agreement between our semiclassical approximation, conventional WKB, and numerical results using numerical worldline loops. I will also show the extension of the worldline instanton technique to multidimensional spatially inhomogeneous electric background fields, for which, WKB failed to apply.