Universal behavior of one-dimensional multispecies branching and annihilating random walks with exclusion

A directed percolation process with two symmetric particle species exhibiting exclusion in one dimension is investigated numerically. It is shown that if the species are coupled by branching (A --> AB, B --> BA), a continuous phase transition will appear at the zero-branching-rate limit belonging to the same universality class as that of the two component branching and annihilating random-walk model with two symmetric offsprings. This class persists even if the branching is biased towards one of the species. If the two systems are not coupled by branching but a hard-core interaction is allowed only the transition will occur at finite branching rate belonging to the usual (1 + 1)-dimensional directed percolation class.