ar X iv : 0 70 8 . 43 32 v 1 [ he p - la t ] 3 1 A ug 2 00 7 Confining vacua and Q - state Potts models with Q < 1

In most Yang-Mills models the vacuum where magnetic monopoles condense coincides with that where center vortices percolate, thus it is not clear which of these two properties is most directly involved in producing confinement. It is pointed out that there is a class of 3D gauge models, which can be though of as duals of Q-state Potts models with Q < 1, where the magnetic monopole condensation is a necessary but not sufficient condition for percolation of center vortices. A set of numerical tests at Q = 1 10 shows that there is a vacuum in which the magnetic monopole condensate does not yield confinement, in the sense that large Wilson loops obey a perimeter law. In such a vacuum the center vortices form a dilute gas of loops. At stronger coupling there is also a truly confining vacuum where both confining mechanisms are present.