Aspects of Causality and Unitarity and Comments on Vortex-like   Configurations in an Abelian Model with a Lorentz-Breaking Term
  The gauge-invariant Chern-Simons-type Lorentz- and CPT-breaking term is here reassessed and a spin-projector method is adopted to account for the breaking (vector) parameter. Issues like causality, unitarity, spontaneous gauge-symmetry breaking and vortex formation are investigated, and consistency conditions on the external vector are identified. 
A. P. Baeta Scarpelli, H. Belich, J. L. Boldo, J.A. Helayel-Neto