Large N, Z_N Strings and Bag Models
  We study Z_N strings in nonabelian gauge theories, when they can be considered as domain walls compactified on a cylinder and stabilized by the flux inside. To make the wall vortex approximation reliable, we must take the 't Hooft large N limit. Our construction has many points in common with the phenomenological bag models of hadrons. 
Stefano Bolognesi