Alain Joye, Charles-Edouard Pfister
Complex WKB Method for 3-Level Scattering Systems
(88K, Latex)
ABSTRACT. In this note, recent developements of the Complex WKB method
allowing to compute the $S$-matrix naturally associated with a
singularly perturbed three-dimensional system of linear differential
equations without turning point on the real axis are reviewed. It is
shown that for a fairly large class of examples, the complex WKB
method gives results far better than what is proven under generic
circumstances. In particular, we show how to compute asymptotically
all exponentially small off-diagonal elements of the corresponding
$S$-matrix.