Dual Wilson Loop and Inter-Monopole Potential in Lattice QCD

We study the dual Wilson loop and the inter-monopole potential(the static potential between the color magnetic monopoles) in the maximally abelian gauge to clarify the dual Higgs mechanism induced by monopole condensation. There is no (color-)electric current in the monopole part, which includes the essence of the nonperturbative QCD, and hence the system can be described by the dual gauge field $B_\mu$ without the singularity like the Dirac string. We find that the dual Wilson loop seems to obey the perimeter law, and the inter-monopole potential becomes Yukawa-type in the infrared region. From the inter-monopole potential, we estimate the dual gluon mass $m_B$ and the effective size $R$ of the monopole: $m_B \simeq 0.5$GeV, $R \simeq 0.35$fm.