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arXiv · 1002.4214

Constructing Infrared Finite Propagators in Inflating Space-time

Jason Kumar·Louis Leblond·Arvind Rajaraman
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Abstract

The usual (Bunch-Davies) Feynman propagator of a massless field is not well defined in an expanding universe due to the presence of infrared divergences. We propose a new propagator which yields infrared finite answers to any correlation function. The key point is that in a de Sitter spacetime there is an ambiguity in the zero-mode of the propagator. This ambiguity can be used to cancel the apparent divergences which arise in some loop calculations in eternally (or semi-eternally) inflating spacetime. We refer to this process as zero-mode modification. The residual ambiguity is fixed by observational measurement. We also discuss the application of this method to calculations involving the graviton propagator.

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Jason Kumar, Louis Leblond, Arvind Rajaraman. 2010-02-22. Constructing Infrared Finite Propagators in Inflating Space-time. https://doi.org/10.1103/physrevd.82.023525

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