Vacuum refractive indices and helicity flip in strong-field QED
arXiv:1312.6419 · doi:10.1103/PhysRevD.89.125003
Abstract
Vacuum birefringence is governed by the amplitude for a photon to flip helicity or polarisation state in an external field. Here we calculate the flip and non-flip amplitudes in arbitrary plane wave backgrounds, along with the induced spacetime-dependent refractive indices of the vacuum. We compare the behaviour of the amplitudes in the low energy and high energy regimes, and analyse the impact of pulse shape and energy. We also provide the first lightfront-QED derivation of the coefficients in the Heisenberg-Euler effective action.
Version 2: additional results added, including discussion of vacuum refractive indices, analysis of flip and non-flip ampltidues at high-energy, additional plots, new title. Now 17 pages, 10 figures