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arXiv · 1703.01158

Compactly supported linearised observables in single-field inflation

Markus B. Fröb·Thomas-Paul Hack·Atsushi Higuchi
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Abstract

We investigate the gauge-invariant observables constructed by smearing the graviton and inflaton fields by compactly supported tensors at linear order in general single-field inflation. These observables correspond to gauge-invariant quantities that can be measured locally. In particular, we show that these observables are equivalent to (smeared) local gauge-invariant observables such as the linearised Weyl tensor, which have better infrared properties than the graviton and inflaton fields. Special cases include the equivalence between the compactly supported gauge-invariant graviton observable and the smeared linearised Weyl tensor in Minkowski and de Sitter spaces. Our results indicate that the infrared divergences in the tensor and scalar perturbations in single-field inflation have the same status as in de Sitter space and are both a gauge artefact, in a certain technical sense, at tree level.

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Markus B. Fröb, Thomas-Paul Hack, Atsushi Higuchi. 2017-08-31. Compactly supported linearised observables in single-field inflation. https://doi.org/10.1088/1475-7516%2F2017%2F07%2F043

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