The interaction between center monopoles in SU(2) Yang-Mills
  We study the potential between a static center monopole and antimonopole in 4d SU(2) Yang-Mills theory. Using a new numerical method, we show that the 't Hooft loop is a dual order parameter with respect to the Wilson loop, for the deconfinement phase transition. We observe a 3d Ising-like critical behaviour for the dual string tension related to the spatial 't Hooft loop as a function of the temperature. 
Ph. de Forcrand (ETH and CERN), M. D'Elia (Pisa) and M. Pepe (ETH)