SU(2) Gauge Theory in Covariant (Maximal) Abelian Gauges
  The local covariant continuum action of an SU(2) gauge theory in covariant Abelian gauges is investigated. It describes the critical limit of an Abelian Lattice Gauge Theory (LGT) with an equivariant BRST-symmetry. This Abelian LGT has previously been proven to be physically equivalent to the SU(2)-LGT. Renormalizability requires a quartic ghost interaction in these nonlinear gauges (also in maximal Abelian gauge). Arguments that a certain global SL(2,R) symmetry is dynamically broken by ghost-antighost condensation in a BCS-like mechanism are presented. The scenario can be viewed as a dynamical Higgs mechanism in the adjoint that gives massive off-diagonal gluons and a BRST quartet of Goldstone bosonsthat decouples from physical observables. The gap parameter is related to the expectation value of the trace anomaly and the consistency of this scenario with the Operator Product Expansion is discussed. 
Martin Schaden