Universal relaxational dynamics of gapped one dimensional models in the   quantum sine-Gordon universality class
  A semiclassical approach to the low-temperature real time dynamics of generic one-dimensional, gapped models in the sine-Gordon model universality class is developed. Asymptotically exact universal results for correlation functions are obtained in the temperature regime T << Delta, where Delta is the energy gap. 
Kedar Damle and Subir Sachdev