Does hardcore interaction change absorbing type critical phenomena?
  It has been generally believed that hardcore interaction is irrelevant to absorbing type critical phenomena because the particle density is so low near an absorbing phase transition. We study the effect of hardcore interaction on the N species branching annihilating random walks with two offspring and report that hardcore interaction drastically changes the absorbing type critical phenomena in a nontrivial way. Through Langevin equation type approach, we predict analytically the values of the scaling exponents, $\nu_{\perp} = 2, z = 2, \alpha = 1/2, \beta = 2$ in one dimension for all N > 1. Direct numerical simulations confirm our prediction. When the diffusion coefficients for different species are not identical, $\nu_{\perp}$ and $\beta$ vary continuously with the ratios between the coefficients. 
Sungchul Kwon, Jysoo Lee, and Hyunggyu Park (Inha Univ., Korea)