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On the cosmological constant problem
Abstract 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 howExpand
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The Quantum Gravitational Back-Reaction on Inflation
Abstract We describe our recent calculation of two-loop corrections to the expansion rate of an initially inflating universe on the manifoldT3× R . If correct, our result proves that quantumExpand
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Weyl Invariance and the Cosmological Constant*
A systematic study of a gravitational action possessing local conformal in-variance is undertaken. The spontaneous breaking of the conformal symmetry induces general relativity as an effective longExpand
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The graviton propagator in de Donder gauge on de Sitter background
We construct the graviton propagator on de Sitter background in exact de Donder gauge. We prove that it must break de Sitter invariance, just like the propagator of the massless, minimally coupledExpand
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Relaxing the cosmological constant
A non-zero cosmological constant allows massless gravitons to self-interact via a coupling of dimension three. If the cosmological constant is positive then the background geometry will subjectExpand
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The physical basis for infra-red divergences in inflationary quantum gravity
We consider tree-order graviton scattering amplitudes on a -dimensional de Sitter background in conformally flat coordinates. Infra-red divergences which cannot be absorbed using conventionalExpand
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de Sitter breaking through infrared divergences
Just because the propagator of some field obeys a de Sitter invariant equation does not mean it possesses a de Sitter invariant solution. The classic example is the propagator of a massless,Expand
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Perils of analytic continuation
A nice paper by Morrison demonstrates the recent convergence of opinion that has taken place concerning the graviton propagator on de Sitter background. We here discuss the few points which remainExpand
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No new physics in conformal scalar-metric theory
Abstract Invariantly regulated conformal scalar-metric theories are shown to be physically equivalent to their pure metric analogs. In particular we explicitly disprove the recent claim that theseExpand
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Graviton propagator in a general invariant gauge on de Sitter
We construct the graviton propagator on de Sitter background in the one parameter family of exact, de Sitter invariant gauges. Our result takes the form of a universal spin two part and a gaugeExpand
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