Gluon Propagators in Linear Covariant Gauge
  The implementation of the linear covariant gauge on the lattice faces a conceptual problem: using the standard compact discretization, the gluon field is bounded, while the four-divergence of the gluon field satisfies a Gaussian distribution, i.e. it is unbounded. This can give rise to convergence problems when a numerical implementation is attempted. In order to overcome this problem, one can use different discretizations for the gluon field or consider an SU(N_c) group with sufficiently large N_c. One can also consider small values of the gauge parameter xi and study numerically the limiting case of xi \to 0, i.e. the Landau gauge. These different approaches will be discussed here. 
Attilio Cucchieri, Tereza Mendes, Gilberto M. Nakamura and Elton M. S.   Santos
hep-lat