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arXiv · 1905.08177

An issue with the classification of the scalar-tensor theories of gravity

Israel Quiros·Roberto De Arcia·Ricardo García-Salcedo·Tame Gonzalez·Francisco Antonio Horta-Rangel
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Abstract

In the bibliography a certain confusion arises in what regards to the classification of the gravitational theories into scalar-tensor theories and general relativity with a scalar field either minimally or non-minimally coupled to matter. Higher-derivatives Horndeski and beyond Horndeski theories that at first sight do not look like scalar-tensor theories only add to the confusion. To further complicate things, the discussion on the physical equivalence of the different conformal frames in which a given scalar-tensor theory may be formulated, makes even harder to achieve a correct classification. In this paper we propose a specific criterion for an unambiguous identification of scalar-tensor theories and discuss its impact on the conformal transformations issue. The present discussion carries not only pedagogical but also scientific interest since an incorrect classification of a given theory as a scalar-tensor theory of gravity may lead to conceptual issues and to the consequent misunderstanding of its physical implications.

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Israel Quiros, Roberto De Arcia, Ricardo García-Salcedo, Tame Gonzalez, Francisco Antonio Horta-Rangel. 2019-05-20. An issue with the classification of the scalar-tensor theories of gravity. https://doi.org/10.1142/s0218271820500479

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