A Remark on Lorentz Violation at Finite Temperature
  We investigate the radiatively induced Chern-Simons-like term in four-dimensional field theory at finite temperature. The Chern-Simons-like term is temperature dependent and breaks the Lorentz and CPT symmetries. We find that this term remains undetermined although it can be found unambiguously in different regularization schemes at finite temperature. 
F.A. Brito, T. Mariz, J.R. Nascimento, E. Passos, and R.F. Ribeiro