An entropy functional yields the Brown-York tensor via conjugate momentum projection, unifying null and timelike hypersurfaces and reproducing equations in scalar-tensor gravity.
Conformal transformations in classical gravitational theories and in cosmology
7 Pith papers cite this work. Polarity classification is still indexing.
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abstract
In recent years, the use of conformal transformation techniques has become widespread in the literature on gravitational theories alternative to general relativity, on cosmology, and on nonminimally coupled scalar fields. Typically, the transformation to the Einstein frame is generated by a fundamental scalar field already present in the theory. In this context, the problem of which conformal frame is the physical one has to be dealt with and, in the general case, it has been clarified only recently; the formulation of a theory in the ``new'' conformal frame leads to departures from canonical Einstein gravity. In this article, we review the literature on conformal transformations in classical gravitational theories and in cosmology, seen both as purely mathematical tools and as maps with physically relevant aspects. It appears particularly urgent to refer the analysis of experimental tests of Brans-Dicke and scalar-tensor theories of gravity, as well as the predictions of cosmological inflationary scenarios, to the physical conformal frame, in order to have a meaningful comparison with the observations.
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A minimal two-field radiative completion of Starobinsky inflation remains observably indistinguishable from the original model on the studied attractor-connected slow-roll branch.
Perturbative holographic calculation yields σ = 1 − q₂(9κQ²/(L² r_h⁴) + 7κ²Q⁴/(4 r_h⁸)) and η/s = (1/(4π))(1 + q₂ 7κ²Q⁴/(2 r_h⁸)) for a nonminimal AdS black brane.
Weyl symmetry of gravity is restored if masses transform as m → Ω^{-1}m under conformal changes, allowing any matter to couple invariantly and potentially accounting for dark energy and dark matter.
The conformal frame problem in scalar-tensor theories stems from incomplete transformation rules for parameters and overlooked Ward identities; active conformal transformations provide the suitable framework while passive ones do not.
In VEP formalism the off-shell spin connection admits a one-parameter family of conformal transformations interpolating between Nieh-Yan and conformally invariant torsion; dynamically generated torsion lacks well-defined conformal properties and affects fermions and conformal scalars.
A critical review of conformal form-invariant parametrization in scalar-tensor theories, testing its novelty relative to existing frames and the universality of frame-invariant physical predictions.
citing papers explorer
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Entropic route to Brown-York tensor: A unified framework for null and timelike hypersurfaces
An entropy functional yields the Brown-York tensor via conjugate momentum projection, unifying null and timelike hypersurfaces and reproducing equations in scalar-tensor gravity.
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Robustness of Starobinsky inflation in a minimal two-field scalar-tensor completion
A minimal two-field radiative completion of Starobinsky inflation remains observably indistinguishable from the original model on the studied attractor-connected slow-roll branch.
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Hydrodynamics of Nonminimal $F^{(a)\alpha \beta } F^{(a)\gamma \lambda } R_{\alpha \gamma } R_{\beta \lambda }$ AdS Black Brane
Perturbative holographic calculation yields σ = 1 − q₂(9κQ²/(L² r_h⁴) + 7κ²Q⁴/(4 r_h⁸)) and η/s = (1/(4π))(1 + q₂ 7κ²Q⁴/(2 r_h⁸)) for a nonminimal AdS black brane.
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Could a so far ignored symmetry of the classical laws of gravity explain the cosmological puzzles?
Weyl symmetry of gravity is restored if masses transform as m → Ω^{-1}m under conformal changes, allowing any matter to couple invariantly and potentially accounting for dark energy and dark matter.
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The Unknown Face of Scalar-Tensor Gravitational Theories
The conformal frame problem in scalar-tensor theories stems from incomplete transformation rules for parameters and overlooked Ward identities; active conformal transformations provide the suitable framework while passive ones do not.
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Different types of torsion and their effect on the dynamics of fields
In VEP formalism the off-shell spin connection admits a one-parameter family of conformal transformations interpolating between Nieh-Yan and conformally invariant torsion; dynamically generated torsion lacks well-defined conformal properties and affects fermions and conformal scalars.
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Conformal form-invariant parametrization of scalar-tensor gravity theories: A critical analysis
A critical review of conformal form-invariant parametrization in scalar-tensor theories, testing its novelty relative to existing frames and the universality of frame-invariant physical predictions.