How (Not) to Palatini

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dc.creatorIglesias, Alberto
dc.creatorKaloper, Nemanja
dc.creatorPadilla, Antonio
dc.creatorPark, Minjoon
dc.date2007-08-09
dc.date2007-08-20
dc.date.accessioned2026-07-07T11:18:33Z
dc.date.available2026-07-07T11:18:33Z
dc.descriptionWe revisit the problem of defining non-minimal gravity in the first order formalism. Specializing to scalar-tensor theories, which may be disguised as `higher-derivative' models with the gravitational Lagrangians that depend only on the Ricci scalar, we show how to recast these theories as Palatini-like gravities. The correct formulation utilizes the Lagrange multiplier method, which preserves the canonical structure of the theory, and yields the conventional metric scalar-tensor gravity. We explain the discrepancies between the naïve Palatini and the Lagrange multiplier approach, showing that the naïve Palatini approach really swaps the theory for another. The differences disappear only in the limit of ordinary General Relativity, where an accidental redundancy ensures that the naïve Palatini works there. We outline the correct decoupling limits and the strong coupling regimes. As a corollary we find that the so-called `Modified Source Gravity' models suffer from strong coupling problems at very low scales, and hence cannot be a realistic approximation of our universe. We also comment on a method to decouple the extra scalar using the chameleon mechanism.
dc.description18 pages, LaTeX; added references and minor improvements in sec 4
dc.identifierhttps://arxiv.org/abs/0708.1163
dc.identifierhttp://arxiv.org/abs/0708.1163
dc.identifierPhys.Rev.D76:104001,2007
dc.identifierdoi:10.1103/PhysRevD.76.104001
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/193382
dc.subjectAstrophysics
dc.subjectGeneral Relativity and Quantum Cosmology
dc.subjectHigh Energy Physics - Phenomenology
dc.subjectHigh Energy Physics - Theory
dc.titleHow (Not) to Palatini
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