 Mean-field joint removal of two chemical species

Equal constant production, individual linear removal, and joint bimolecular removal give $d({\mu }_1-{\mu }_2)/dt=-\beta ({\mu }_1-{\mu }_2)$. For $\beta >0$ the unique stable equilibrium is symmetric and solves $\lambda =\beta \mu +C{\mu }^2$. For $\beta =0<C$, every point on ${\mu }_1{\mu }_2=\lambda /C$ is an equilibrium: the difference is conserved and trajectories approach the equilibrium on their own constant-difference line.

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