Discontinuous Phase Transition in an Exactly Solvable One-Dimensional Creation-Annihilation System

An exactly solvable reaction-diffusion model consisting of first-class particles in the presence of a single second-class particle is introduced on a one-dimensional lattice with periodic boundary condition. The number of first-class particles can be changed due to creation and annihilation reactions. It is shown that the system undergoes a discontinuous phase transition in contrast to the case where the density of the second-class particles is finite and the phase transition is continuous.
Comment: Revised, 8 pages, 1 EPS figure. Accepted for publication in Journal of Statistical Mechanics: theory and experiment