Collective roughening of elastic lines with hard core interaction in a   disordered environment
  We investigate by exact optimization methods the roughening of two and three-dimensional systems of elastic lines with point disorder and hard-core repulsion with open boundary conditions. In 2d we find logarithmic behavior whereas in 3d simple random walk-like behavior. The line 'forests' become asymptotically completely entangled as the system height is increased at fixed line density due to increasing line wandering. 
Viljo Pet\"aj\"a, Mikko Alava, Deok-Sun Lee, Heiko Rieger