H. Hinrichsen et al., ON MATRIX PRODUCT GROUND-STATES FOR REACTION-DIFFUSION MODELS, Journal of physics. A, mathematical and general, 29(11), 1996, pp. 2643-2649
We discuss a new mechanism leading to a matrix product form for the st
ationary state of one-dimensional stochastic models. The corresponding
algebra is quadratic and involves four different matrices. For the ex
ample of a coagulation-decoagulation model explicit four-dimensional r
epresentations are given and exact expressions for various physical qu
antities are recovered. We also find the general structure of n-point
correlation functions at the phase transition.