On the SL(2,R) symmetry in Yang-Mills Theories in the Landau,   Curci-Ferrari and Maximal Abelian Gauge
  The existence of a SL(2,R) symmetry is discussed in SU(N) Yang-Mills in the maximal Abelian Gauge. This symmetry, also present in the Landau and Curci-Ferrari gauge, ensures the absence of tachyons in the maximal Abelian gauge. In all these gauges, SL(2,R) turns out to be dynamically broken by ghost condensates. 
D. Dudal, V.E.R. Lemes, M. Picariello, M.S. Sarandy, S.P. Sorella, H.   Verschelde