Strong/weak duality symmetries for Jacobi–Gordon field theory through elliptic functions

It is shown that the standard sin/sinh Gordon field theory with the strong/weak duality symmetry of its quantum S-matrix, can be formulated in terms of elliptic functions with their duality symmetries, which will correspond to the classical realization of that quantum symmetry. Specifically we show that the so called self-dual point that divides the strong and the weak coupling regimes, corresponds only to one point of a set of fixed points under the duality transformations for the elliptic functions. Furthermore, the equations of motion can be solved in exact form in terms of the inverse elliptic functions; in spontaneous symmetry breaking scenarios, these solutions show that kink-like solitons can decay to cusp-like solitons.