On nonequilibrium dynamics in quantum integrable systems

We consider a situation where the parameters of a Hamiltonian describing a quantum system change abruptly. To study the question of the relaxation of the system to a new equilibrium, it is necessary to expand the eigenfunctions of the original Hamiltonian into the eigenfunctions of the new one. I consider this problem using the Lieb-Liniger model as an example. In my report, I will discuss some preliminary results.