Quantum field theory and the 'elliptic interpretation' of de Sitter spacetime

The elliptic version of spacetime is obtained by deeming antipodes to represent the same world point or event. We investigate the consequences of this identification for QFT as formulated in de Sitter space and its implications for inflation. Antipodally symmetric and antisymmetric fields and Green functions are described. We calculate for these fields the expectation values of the square of the field operator and stress-tensors in the family of de Sitter O(1,4) invariant vacua and study limiting cases of interest. In the inflationary regime the antiposal identification gives for <Φ2> a value which differs in a factor 2 from the ordinary Bunch-Davies value. The modifactions introduced to vanish in the conformally invariant case. We also discuss the massless and minimally coupled ordinary theory with identification for the vacuum states which are O(4), O(1,3) and E(3) invariant and calculate the stress-tensors for them. (orig.)