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arXiv · 2003.02741

New class of hybrid metric-Palatini scalar-tensor theories of gravity

Andrzej Borowiec·Aleksander Kozak
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Abstract

A class of scalar-tensor theories (STT) including a non-metricity that unifies metric, Palatini and hybrid metric-Palatini gravitational actions with non-minimal interaction is proposed and investigated from the point of view of their consistency with generalized conformal transformations. It is shown that every such theory can be represented on-shell by a purely metric STT possessing the same solutions for a metric and a scalar field. A set of generalized invariants is also proposed. This extends the formalism previously introduced in \cite{kozak2019}. We then apply the formalism to Starobinsky model, write down the Friedmann equations for three possible cases: metric, Palatini and hybrid metric-Palatini, and compare some inflationary observables.

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Andrzej Borowiec, Aleksander Kozak. 2020-03-05. New class of hybrid metric-Palatini scalar-tensor theories of gravity. https://doi.org/10.1088/1475-7516/2020/07/003

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