Dr. Karthik Rajeev

Very strong classical electromagnetic fields are believed to be generated by astrophysical objects like Pulsars. Presence of such strong background fields leads to significant deviations from vacuum amplitudes of, say, between photons and electrons. Several available analytical results suggests that such deviations have non-perturbative character, which in turn implies that treating the external background as small correction to the vacuum is not an ideal approach. To gain insights about such non-perturbative amplitudes, it is advantageous to consider external backgrounds which are sufficiently general but also enable exact computations. In light of this, after a brief general introduction to QED in external backgrounds, we will discuss recent advances in exact computation of multiphoton amplitudes in a general plane wave background using worldline path integral methods.