Quenching the XXZ spin chain: quench action approach versus generalized Gibbs ensemble

Abstract

Following our previous work [PRL 113 (2014) 09020] we present here a detailed\ncomparison of the quench action approach and the predictions of the generalized\nGibbs ensemble, with the result that while the quench action formalism\ncorrectly captures the steady state, the GGE does not give a correct\ndescription of local short-distance correlation functions. We extend our\nstudies to include another initial state, the so-called q-dimer state. We\npresent important details of our construction, including new results concerning\nexact overlaps for the dimer and q-dimer states, and we also give an exact\nsolution of the quench-action-based overlap-TBA for the q-dimer. Furthermore,\nwe extend our computations to include the xx spin correlations besides the zz\ncorrelations treated previously, and give a detailed discussion of the\nunderlying reasons for the failure of the GGE, especially in the light of new\ndevelopments.\n