On Virtual Scalar Fields in a Conformally Flat FLRW Spacetime

Comment: I have made some substantial, necessary changes to the manuscript. I have accounted for the gravitational coupling of the scalar field in a conformally flat FLRW spacetime. In this case the EoM for the auxilliary field reduces to a harmonic oscillator with a time-independent angular frequency. This implies that any inertial observers all agree on the choice of virtual vacuum states, or in other words that the Bogolyubov coefficients become non-existent in this particular case. We postulate that the wavenumber k must be quantized in order to be able to regularize the vev by zeta regularization, though this summability likely is not covariant in general. Some direct implications of this emerging picture are derived and plausible conclusions drawn.

The article is more rigorous, stylistic and compact.