Short distance correlators in the XXZ spin chain for arbitrary string distributions

Abstract

In this letter we consider expectation values of local correlators in highly\nexcited states of the spin-1/2 XXZ chain. Assuming that the string hypothesis\nholds we formulate the following conjecture: The correlation functions can be\ncomputed using the known factorized formulas of the finite temperature\nsituation, if the building blocks are computed via certain linear integral\nequations using the string densities only. We prove this statement for the\nnearest neighbour z-z correlator for states with arbitrary string densities.\nAlso, we check the conjecture numerically for other correlators in the finite\ntemperature case. Our results pave the way towards the computation of the\nstationary values of correlators in non-equilibrium situations using the\nso-called quench-action approach.\n