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arXiv · 1612.07749

Higher-order theories of gravity: diagnosis, extraction and reformulation via non-metric extra degrees of freedom

Alessio Belenchia·Marco Letizia·Stefano Liberati·Eolo Di Casola
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Abstract

Modifications of Einstein's theory of gravitation have been extensively considered in the past years, in connection to both cosmology and quantum gravity. Higher-curvature and higher-derivative gravity theories constitute the main examples of such modifications. These theories exhibit, in general, more degrees of freedom than those found in standard General Relativity; counting, identifying, and retrieving the description/representation of such dynamical variables is currently an open problem, and a decidedly nontrivial one. In this work we review, via both formal arguments and custom-made examples, the most relevant methods to unveil the gravitational degrees of freedom of a given model, discussing the merits, subtleties and pitfalls of the various approaches.

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Alessio Belenchia, Marco Letizia, Stefano Liberati, Eolo Di Casola. 2016-12-22. Higher-order theories of gravity: diagnosis, extraction and reformulation via non-metric extra degrees of freedom. https://doi.org/10.1088/1361-6633%2Faaa4ab

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