Correlation Functions of the Non-Ideal Gas of Sine-Gordon Solitons

Abstract

Extensive studies on statistical mechanics of one-dimensional soliton-bearing systems have revealed that solitons, as well as linear excitations such as phonons, can be considered as elementary excitations [1]. Soliton contributions to various thermodynamic quantities and correlation functions have been calculated within the ideal soliton gas approximation [2,3,4]. In this theory the soliton-phonon interaction is taken into account, and the interaction between solitons is neglected. This approximation is valid at low temperatures. Recently the importance of the soliton-soliton interaction has been implied in connection with the anomaly of specific heat [5,6]. In this paper we study the effect of the interaction between solitons on various correlation functions of the sine-Gordon model. These quantities are of particular interest, since they are accessible by neutron scattering and NMR experiments on one-dimensional magnets such as CsNiF₃ and (CH₃)₄NMnCl₃ (TMMC).