QUANTUM-STATISTICAL MECHANICS OF EXTENDED OBJECTS .1. KINKS IN THE ONE-DIMENSIONAL SINE-GORDON SYSTEM

Making use of thermal-Green's-function technique, we study the quantum-statistical mechanics of a sine-Gordon system in 1 + 1 dimensions. In the weak-coupling limit, the temperature dependences of the soliton energy, Es, the soliton inertial mass, and the soliton density are determined. At high temperatures (T>m, where m is the mass of the fundamental field), Es decreases monotonically as the temperature increases, and Es jumps to zero around T=Tcr (e-1Es0), where Es0 is the soliton energy at T=0 K. The soliton density agrees with the classical statistical-mechanics results for Tcr>T≪m, if Es in the classical theory is replaced by the temperature-dependent one of the present theory. © 1979 The American Physical Society.