Semiclassical expansion; beyond WKB
Pierre Cartier, Cécile DeWitt-Morette
When “WKB breaks down... ” then rainbows and glory scattering may appear. In other words, and with the notation of chapter 4, when the hessian S ′ ′ (q) of the functional S is degenerate S ′ ′ (q) · ξξ = 0 (5.1)
Cambridge University Press eBooks•Nov 30, 2006•0 citations