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We derive the propagator for a massive vector field on a de Sitter background of arbitrary dimension. This propagator is de Sitter invariant and possesses the proper flat spacetime and massless limits. Moreover, the retarded Green's function inferred from it produces the correct classical response to a test source. Our result is expressed in a tensor basis… (More)

We describe our recent calculation of two-loop corrections to the expansion rate of an initially inflating universe on the manifold T 3 × ℜ. If correct, our result proves that quantum gravitational effects slow the rate of inflation by an amount which becomes non-perturbatively large at late times. In a preliminary discussion of basic issues we show that… (More)

We consider the quantum gravitational back-reaction on an initially inflating, homogeneous and isotropic universe whose topology is T 3 × ℜ. Although there is no secular effect at one loop, an explicit calculation shows that two-loop processes act to slow the rate of expansion by an amount which becomes non-perturbatively large at late times. By exploiting… (More)

During inflation explicit perturbative computations of quantum field theories which contain massless, non-conformal fields exhibit secular effects that grow as powers of the logarithm of the inflationary scale factor. Starobinski˘ ı's technique of stochastic inflation not only reproduces the leading infrared logarithms at each order in perturbation theory,… (More)

We evaluate the one and two loop contributions to the expectation values of two coincident and gauge invariant scalar bilinears in the theory of massless, minimally coupled scalar quantum electrodynamics on a locally de Sitter background. One of these bilinears is the product of two covariantly differentiated scalars, the other is the product of two… (More)

We stochastically formulate the theory of scalar quantum electrodynamics on a de Sitter background. This reproduces the leading infrared logarithms at each loop order. It also allows one to sum the series of leading infrared logarithms to obtain explicit, nonperturbative results about the late time behavior of the system. One consequence is confirmation of… (More)

- I Antoniadis, N C Tsamis
- 1984

We prove that Weyl invariant theories of gravity possess a remarkable property which, under very general assumptions, explains the stability of flat space-time. We show explicitly how conformal invariance is broken spontaneously by the vacuum expectation value of an unphysical scalar field; this process induces general relativity as an effective long… (More)

- Nikolaos Tsamis, Vaggelis Giannikas, Duncan C. McFarlane, Wenrong Lu, James Strachan
- Service Orientation in Holonic and Multi-agent…
- 2015

During inflation explicit perturbative computations of quantum field theories which contain massless, non-conformal fields exhibit secular effects that grow as powers of the logarithm of the inflationary scale factor. Starobinski˘ ı's technique of stochastic inflation not only reproduces the leading infrared logarithms at each order in perturbation theory,… (More)