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T: Teilchenphysik

T 408: Feldtheorie

T 408.7: Vortrag

Dienstag, 21. März 2000, 18:00–18:15, H\,204

Towards the non-Abelian Meissner effect in SU(2) lattice gauge theory — •Alexandra Schäfke and Kurt Langfeld — Institut für Theoretische Physik, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen

After Maximal Abelian gauge fixing (MAG), SU(2) lattice gauge theory is projected onto a theory with a residual U(1) gauge group. The constituents of the latter theory are colour-magnetic monopoles and colour-photons. Confinement is attributed to an Abelian Meissner effect: condensation of these monopoles implies that the colour electric flux is squeezed into flux tubes. It has been known for some time that colour states which are neutral with respect to the residual U(1) gauge are not confined by the colour monopole condensate. This contradiction to the experiment requires a refinement of the dual superconductor picture. To this aim, we propose a new type of gauge fixing which appears as a generalization of the Maximal Abelian gauge fixing. Our numerical simulations show that the errors which are induced by projection in the latter and the MAG case are strongly reduced by resorting to the new gauge. For putting the new gauge into a proper context, we numerically investigate, by virtue of a gauge fixing parameter, a gauge fixing which smoothly interpolates between the MAG and the new gauge. For a wide range of the gauge fixing parameters, the vacuum decomposes into domains which show colour ferromagnetism. Since coloured states only correspond to ”neutral” particles in one particular domain, these states are confined on large scales. This solves the neutral particle problem.