SCALE-INVARIANCE OF NONCONSERVED QUANTITIES IN DRIVEN SYSTEMS

Noisy nonequilibrium systems involving locally conserved quantities ty pically exhibit generic scale invariance-infinite correlation lengths and the associated algebraic decay of correlations without the tuning of external parameters. It is shown here that if such a conserved fiel d, phi(c), is coupled linearly to a nonconserved one, phi(n), generic power-law decays are induced in the correlations of phi(n). When symme try prevents linear coupling, correlations of the phi(n) field decay e xponentially under generic conditions, unless phi(n) experiences a bro ken symmetry, in which case linear coupling and hence algebraic decays can be generated. Numerical support for these results in simple conse rving coupled map lattices is presented.