Computing Electromagnetic Effects in Fully Unquenched QCD
  The inclusion of electromagnetic effects in unquenched QCD can be accomplished using ensembles generated in dynamical simulations with pure QCD provided the change in the quark determinant induced by a weak electromagnetic field can be efficiently computed. A stochastic technique for achieving this in the case of dynamical domain wall calculations is described. 
A. Duncan, E. Eichten and R. Sedgewick