Infinite-time Average of Local Fields in an Integrable Quantum Field Theory after a Quantum Quench

Abstract: The infinite-time average of the expectation values of local fields of any interacting quantum theory after a global quench process are key quantities for matching theoretical and experimental results. For quantum integrable field theories, we show that they can be obtained by an ensemble average that employs a particular limit of the Form Factors of local fields and quantities extracted by the Generalized Bethe Ansatz.