Long-distance behavior of temperature correlation functions in the one-dimensional Bose gas

We describe a Bethe ansatz-based method to derive, starting from a multiple integral representation, the long-distance asymptotic behavior at finite temperature of the density-density correlation function in the interacting one-dimensional Bose gas. We compute the correlation lengths in terms of solutions of non-linear integral equations of the thermodynamic Bethe ansatz type. Finally, we establish a connection between the results obtained in our approach and the correlation lengths stemming from the quantum transfer matrix method.