Quantum fluctuations of the color flux tube
  The quantum fluctuations of the flux tube joining two static sources in the confining phase of a lattice gauge theory are described by an effective string theory. The predictions of the latter for ratios of Wilson loops of equal perimeter do not contain any free parameters, and can be computed exactly for large Wilson loops. We compare these predictions with numerical results in 3D $Z_2$ gauge theory, finding complete agreement. 
P. Provero