Three-species diffusion-limited reaction with continuous density-decay exponents

We introduce a model of three-species two-particle diffusion-limited reactions or B, or C, and or A, with three persistence parameters (survival probabilities in reaction) of the hopping particle. We consider isotropic and anisotropic diffusion (hopping with a drift) in one dimension. We find that the particle density decays as a power law for certain choices of the persistence parameter values. In the anisotropic case, on one symmetric line in the parameter space, the decay exponent is monotonically varying between the values close to 1/3 and 1/2. On another, less symmetric line, the exponent is constant. For most parameter values, the density does not follow a power law. We also calculated various characteristic exponents for the distance of nearest particles and domain structure. Our results support the recently proposed possibility that one-dimensional diffusion-limited reactions with a drift do not fall within a limited number of distinct universality classes.