The grand-canonical asymmetric exclusion process and the one-transit walk

The one-dimensional asymmetric exclusion process (ASEP) is a paradigm for nonequilibrium dynamics, in particular driven diffusive processes. It is usually considered in a canonical ensemble in which the number of sites is fixed. We observe that the grand-canonical partition function for the ASEP is remarkably simple. It allows a simple direct derivation of the asymptotics of the canonical normalization in various phases and of the correspondence with one-transit walks recently observed by Brak et al.