Exact matrix product states for parallel dynamics: Open boundaries and excess mass on the ring

Abstract. In this paper it is shown that the steady-state weights of the asymmetric simple exclusion process (ASEP) with open boundaries and parallel update can be written as a product of a scalar pair-factorized and a matrix-product state. This type of state is also obtained for an ASEP on a ring in which particles can move one or two sites. The dynamics leads to the formation of an excess hole that plays the role of a defect. We expect the process to play a similar role for parallel dynamics as the well-known ASEP with a single defect-particle (that is obtained in the continuoustime limit) especially for the study of shocks. The process exhibits a first-order phase transition between two phases with different defect velocities. These are calculated exactly from the process-generating function.