The Bethe Ansatz and the Tzitz\'eica-Bullough-Dodd equation
  The theory of classically integrable nonlinear wave equations, and the Bethe Ansatz systems describing massive quantum field theories defined on an infinite cylinder, are related by an important mathematical correspondence that still lacks a satisfactory physical interpretation. In this paper we shall describe this link for the case of the classical and quantum versions of the (Tzitz\'eica-)Bullough-Dodd model. 
Patrick Dorey, Simone Faldella, Stefano Negro and Roberto Tateo
math-ph hep-th math.MP quant-ph