PARTIALLY ASYMMETRIC EXCLUSION PROCESS WITH OPEN BOUNDARIES

Exclusive diffusion on a one-dimensional lattice is studied. In the mo del, particles hop stochastically in both directions but with differen t rates. At the ends of the lattice, particles are injected and remove d. The exact stationary probability measure is represented in the form of a matrix product, as a generalization of the solution given by Der rida et al. [J. Phys. A 26, 1493 (1993)] for the fully asymmetric proc ess. The phase diagram of the current on the infinite lattice is obtai ned. Analytic expressions for the current in the different phases are derived. The model is equivalent to an XXZ-Heisenberg chain with a cer tain type of boundary terms, the ground state of which corresponds to the stationary solution of the master equation.