In this paper, we consider /4 and Sin–Gordon theory and also we construct the general form of the stability equation. In order to discuss the stability, we use factorization method. Using the associated Jacobi differential equation, we obtain the exactly bound states of the /4 and Sine–Gordon theory. According to the supersymmetry approach, these bound states are represented by two pairs of first order differential operators. 2006 Elsevier Ltd. All rights reserved
