Z(2)-symmetric center vortex model with a first-order deconfinement   transition
  A random vortex world-surface model for the infrared sector of Sp(2) Yang-Mills theory is constructed. The Sp(2) gauge group, while allowing for the same set of center vortex fluxes as the SU(2) gauge group, induces a significantly different dynamics on those vortex fluxes, which manifests itself in a first-order deconfinement phase transition. As shown by the construction presented here, a new vortex effective action term which can be interpreted in terms of a vortex stickiness can be used to drive the deconfinement transition towards first-order behavior. The available data from lattice Sp(2) Yang-Mills theory are reproduced quantitatively and, in addition, predictions for the behavior of the spatial string tension at high temperatures are presented. 
M.Engelhardt and B.Sperisen (NMSU)