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1. Verfasser: Karananas, Georgios K.
Format: Preprint
Veröffentlicht: 2024
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Online-Zugang:https://arxiv.org/abs/2407.09598
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author Karananas, Georgios K.
author_facet Karananas, Georgios K.
contents Studying the spectrum of (pure) $R^2$ gravity on Minkowski background inevitably results into a Catch-22: any consistent interpretation of its particle dynamics dictates that no accidental gauge symmetries emerge, a requirement that cannot be fulfilled when the theory is studied on Minkowski. For the case at hand, there is an emergent gauge redundancy corresponding to a transverse-traceless shift of the graviton. This has detrimental consequences since it empties the spectrum from all particle states. Being an artifact of the linearized approximation on top of Minkowski background, the symmetry does not persist at higher orders and degrees of freedom are reintroduced via interactions, making $R^2$ gravity infinitely strongly-coupled. Provided that the theory is considered on appropriate backgrounds -- for instance de Sitter spacetime -- or is supplemented with the Einstein-Hilbert term, $R^2$ gravity propagates the two usual graviton polarizations plus one additional (massless or massive) scalar field. We explicitly demonstrate that in a fully covariant manner.
format Preprint
id arxiv_https___arxiv_org_abs_2407_09598
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The particle content of $R^2$ gravity revisited
Karananas, Georgios K.
High Energy Physics - Theory
General Relativity and Quantum Cosmology
Studying the spectrum of (pure) $R^2$ gravity on Minkowski background inevitably results into a Catch-22: any consistent interpretation of its particle dynamics dictates that no accidental gauge symmetries emerge, a requirement that cannot be fulfilled when the theory is studied on Minkowski. For the case at hand, there is an emergent gauge redundancy corresponding to a transverse-traceless shift of the graviton. This has detrimental consequences since it empties the spectrum from all particle states. Being an artifact of the linearized approximation on top of Minkowski background, the symmetry does not persist at higher orders and degrees of freedom are reintroduced via interactions, making $R^2$ gravity infinitely strongly-coupled. Provided that the theory is considered on appropriate backgrounds -- for instance de Sitter spacetime -- or is supplemented with the Einstein-Hilbert term, $R^2$ gravity propagates the two usual graviton polarizations plus one additional (massless or massive) scalar field. We explicitly demonstrate that in a fully covariant manner.
title The particle content of $R^2$ gravity revisited
topic High Energy Physics - Theory
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2407.09598