A perfect monopole action for SU(2) QCD

We found a quantum perfect lattice action in the 4-dimensional monopole current theory which is known as an effective theory in the infrared region of QCD. The perfect monopole action is transformed exactly into a lattice action of a string model. When the monopole interactions are weak as in the case of infrared SU(2) QCD, the string interactions are strong. The static potential and the string tension in this region can be estimated analytically by the use of the strong coupling expansion.