We propose that the SU(2) Yang-Mills theory can be interpreted as a two-band dual superconductor with an interband Josephson coupling. We discuss various consequences of this interpretation including electric flux quantization, confinement of vortices with fractional flux, and the possibility that a closed vortex loop exhibits exotic exchange statistics.
PACS numbers:Color confinement remains one of the great mysteries of modern high energy physics [1]. Several approaches have been proposed to explain why and how a SU(N) Yang-Mills theory supports confining colored strings, including a variety of dual superconductor and central vortex models [2]. But until now the relevant dynamical string degrees of freedom have not been identified.Recently it has been proposed [3] that the string variables in a Yang-Mills theory could relate to an appropriate decomposion of the gauge field. In the simplest case of SU(2) considered here, we start by separating A a µ (a = 1, 2, 3) into its U(1) Cartan component A 3 µ ≡ A µ while the off-diagonal A i µ (i = 1, 2) we combine into the complex variableWe introduce the U(1) covariant derivativesHere we have explicitely displayed a gauge fixing and Faddeev-Popov ghost (P, η) [4] only for the off-diagonal A 1,2 µ components. The remaining Cartan U(1) gauge invariance can be fixed similarly. But we shall find that this U(1) invariance can also be eliminated directly, by casting the Lagrangian in a form that involves only manifestly U(1) invariant variables. In the following we shall mostly exclude the ghosts from explicit equations. Their inclusion has very little if any conceptual impact. For the present purposes it is important to note that the sole effect of the fourth term in the r.h.s. of (1) is a redefinition of the gauge parameter ξ → ξ − 1 in the gauge fixing (fifth) term. Thus these terms can be combined. In particular, in the ξ → ∞ limit the fourth term becomes entirely immaterial. This limit yields the Landau version of the maximal abelian gaugewhich we shall assume has been imposed. We note that this gauge condition appears as the variational equation when one locates the extrema of the functionalwith respect to the full SU(2) gauge transformations. Thus, even though the field ρ is in general a gauge dependent quantity, its extremum values with respect to gauge transformations are manifestly gauge independent when the theory is subject to the Landau version of maximal abelian gauge. Recent numerical investigations indicate that in strong coupling regime the extrema of ρ are nonvanishing [5] The antisymmetric tensor