Multi-Scaling of Correlation Functions in Single Species Reaction-Diffusion Systems

Abstract

We derive the multi-fractal scaling of probability distributions of multi-particle configurations for the binary reaction-diffusion system $A+A\to \varnothing$ in $d\le 2$ and for the ternary system $3A\to \varnothing$ in $d=1$. For the binary reaction we find that the probability $P_t(N,\Delta V)$ of finding $N$ particles in a fixed volume element $\Delta V$ at time $t$ decays in the limit of large time as $(\frac{\ln t}{t}{)}^N(\ln t{)}^{-\frac{N(N-1)}{2}}$ for $d=2$ and $t^{-Nd/2}t^{-\frac{N(N-1)ε}{4}+\mathcal{O}(\ep^2)}$ for $d<2$. Here $\ep=2-d$. For the ternary reaction in one dimension we find that $P_t(N,\Delta V)\sim (\frac{\ln t}{t}{)}^{N/2}(\ln t{)}^{-\frac{N(N-1)(N-2)}{6}}$. The principal tool of our study is the dynamical renormalization group. We compare predictions of $\ep$-expansions for $P_t(N,\Delta V)$ for binary reaction in one dimension against exact known results. We conclude that the $\ep$-corrections of order two and higher are absent in the above answer for $P_t(N,\Delta V)$ for $N=1,2,3,4$. Furthermore we conjecture the absence of $\ep^2$-corrections for all values of $N$.

10 pages, 6 figures