Magnetic monopole loop for the Yang-Mills instanton

We investigate 't Hooft-Mandelstam monopoles in QCD in the presence of a single classical instanton configuration. The solution to the maximal Abelian projection is found to be a circular monopole trajectory with radius R centered on the instanton. At zero loop radius, there is a marginally stable (or flat) direction for loop formation to O(R(4)lnR). We argue that loops will form, in the semiclassical limit, due to small perturbations such as the dipole interaction between instanton-anti-instanton pairs. As the instanton gas becomes a liquid, the percolation of the monopole loops may, therefore, provide a semiclassical precursor to the confinement mechanism.