We investigate properties of the states of a Hermitian spin-½ field in a Robertson-Walker spacetime constructed by an energy-minimization requirement. It is shown that the singularity structure of the commutator function $〈\left[\hat{\Psi }\mathrm{}\right(x),\hat{\bar{\Psi }}(x^{\prime }\left)\right]〉$ for these states is such that current renormalization theory yields an infinite value for the renormalized expectation value of the trace of the stress tensor.

• Received 18 June 1984

DOI:https://doi.org/10.1103/PhysRevD.30.2573