Vacuum stress-tensor in SSB theories
  The renormalized energy-momentum tensor of vacuum has been deeply explored many years ago. The main result of these studies was that such a tensor should satisfy the conservation laws which reflects the covariance of the theory in the presence of loop corrections. In view of this general result we address two important questions, namely how to implement the momentum cut-off in a covariant way and whether this general result holds in the theory with Spontaneous Symmetry Breaking. In the last case some new interesting details arise and although the calculations are more involved we show that the final result satisfies the conservation laws. 
Manuel Asorey, Petr M. Lavrov, Baltazar J. Ribeiro, Ilya L. Shapiro
hep-th gr-qc hep-ph