Exact Thermodynamics of the Double sinh-Gordon Theory in 1+1-Dimensions

Abstract

We study the classical thermodynamics of a 1+1-dimensional double-well sinh-Gordon theory. Remarkably, the Schrodinger-like equation resulting from the transfer integral method is quasi-exactly solvable at several temperatures. This allows exact calculation of the partition function and some correlation functions above and below the short-range order (``kink'') transition, in striking agreement with high resolution Langevin simulations. Interesting connections with the Landau-Ginzburg and double sine-Gordon models are also established.

4 pages, 3 figures (embedded using epsf), uses RevTeX plus macro (included). Minor revision to match journal version, Phys. Rev. Lett. (in press)