Correlations after quantum quenches in the XXZ spin chain: Failure of   the Generalized Gibbs Ensemble
  We study the nonequilibrium time evolution of the spin-1/2 anisotropic Heisenberg (XXZ) spin chain, with a choice of dimer product and Neel states as initial states. We investigate numerically various short-ranged spin correlators in the long-time limit and find that they deviate significantly from predictions based on the generalized Gibbs ensemble (GGE) hypotheses. By computing the asymptotic spin correlators within the recently proposed quench-action formalism [Phys. Rev. Lett. 110, 257203 (2013)], however, we find excellent agreement with the numerical data. We, therefore, conclude that the GGE cannot give a complete description even of local observables, while the quench-action formalism correctly captures the steady state in this case. 
B. Pozsgay, M. Mesty\'an, M. A. Werner, M. Kormos, G. Zar\'and, G.   Tak\'acs
cond-mat.stat-mech nlin.SI