  Boundary conditions may change the phase diagram of non-equilibrium
statistical systems like the one-dimensional asymmetric simple exclusion
process with and without particle number conservation. Using the quantum
Hamiltonian approach, the model is mapped onto an XXZ quantum chain and solved
using the Bethe ansatz. This system is related to a two-dimensional vertex
model in thermal equilibrium. The phase transition caused by a point-like
boundary defect in the dynamics of the one-dimensional exclusion model is in
the same universality class as a continous (bulk) phase transition of the
two-dimensional vertex model caused by a line defect at its boundary.
(hep-th/yymmnnn)
