Chaos and residual correlations in pinned disordered systems
  We study, using functional renormalization (FRG), two copies of an elastic system pinned by mutually correlated random potentials. Short scale decorrelation depend on a non trivial boundary layer regime with (possibly multiple) chaos exponents. Large scale mutual displacement correlation behave as $|x-x'|^{2 \zeta - \mu}$, the decorrelation exponent $\mu$ proportional to the difference between Flory (or mean field) and exact roughness exponent $\zeta$. For short range disorder $\mu >0$ but small, e.g. for random bond interfaces $\mu = 5 \zeta - \epsilon$, $\epsilon=4-d$, and $\mu = \epsilon (\frac{(2 \pi)^2}{36} - 1)$ for the one component Bragg glass. Random field (i.e long range) disorder exhibits finite residual correlations (no chaos $\mu = 0$) described by new FRG fixed points. Temperature and dynamic chaos (depinning) are discussed. 
Pierre Le Doussal