Phonon-Kink Interference in the ϕ4 Model

By means of a conventional steepest descent approach equivalent to the static limit of the ideal gas phenomenology, we derive the low temperature static properties of the 4 or double well potential model. We focus in particular on the phonon-phonon correlations and demonstrate that the thermal activation of kinks gives rise to a cross over from a pure exponential decay to damped oscillations. This is a novel feature of the 4 model demonstrating the strong coherence effects characteristic of non linear soliton bearing systems.