This book presents a functional approach to the construction, use and approximation of Green.s functions and their associated ordered exponentials. After a brie... » 

This book presents a functional approach to the construction, use and approximation of Green.s functions and their associated ordered exponentials. After a brief historical introduction, the author discusses new solutions to problems involving particle production in crossed laser fields and non-constant electric fields. Applications to problems in potential theory and quantum field theory are covered, along with approximations for the treatment of color fluctuations in high-energy QCD scattering, and a model for summing classes of eikonal graphs in high-energy scattering problems. «