Magnetic Monopoles and the Topology of Gauge Fields

There are two basic low energy features of strong interactions, which should be explained by QCD: confinement and spontaneous breaking of chiral symmetry. While the latter can be more or less explained in terms of instantons [1], confinement is much less understood. Recently, however, much evidence has been accumulated for the idea that confinement is realized as a dual Meissner effect [2], at least in the so-called Abelian gauges [3]. In these gauges magnetic monopoles arise, which have to condense in order to form the dual superconducting ground state. From the conceptional point of view it is unsatisfactory that spontaneous breaking of chiral symmetry and confinement is attributed to different types of field configurations. This is because lattice calculations show that both phenomena occur at about the same energy scale. In fact, lattice calculations indicate that the deconfinement phase transition and the restoration of chiral symmetry occur at about the same temperature.