Grand Canonical simulations of string tension in elastic surface model
  We report a numerical evidence that the string tension \sigma can be viewed as an order parameter of the phase transition, which separates the smooth phase from the crumpled one, in the fluid surface model of Helfrich and Polyakov-Kleinert. The model is defined on spherical surfaces with two fixed vertices of distance L. The string tension \sigma is calculated by regarding the surface as a string connecting the two points. We find that the phase transition strengthens as L is increased, and that \sigma vanishes in the crumpled phase and non-vanishes in the smooth phase. 
Hiroshi Koibuchi