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Evading equivalence principle violations, cosmological, and other experimental constraints in scalar field theories with a strong coupling to matter
We show that, as a result of nonlinear self-interactions, it is feasible, at least in light of the bounds coming from terrestrial tests of gravity, measurements of the Casimir force and thoseExpand
f(R) gravity and chameleon theories
We analyze f(R) modifications of Einstein's gravity as dark energy models in the light of their connection with chameleon theories. Formulated as scalar-tensor theories, the f(R) theories imply theExpand
Testing Chameleon Theories with Light Propagating through a Magnetic Field
It was recently argued that the observed PVLAS anomaly can be explained by chameleon field theories in which large deviations from Newton's law can be avoided. Here we present the predictions for theExpand
Detecting chameleons through Casimir force measurements
The best laboratory constraints on strongly coupled chameleon fields come not from tests of gravity per se but from precision measurements of the Casimir force. The chameleonic force between twoExpand
Nonlinear structure formation with the environmentally dependent dilaton
We have studied the nonlinear structure formation of the environmentally dependent dilaton model using N-body simulations. We find that the mechanism of suppressing the scalar fifth force inExpand
Tuning the mass of chameleon fields in Casimir force experiments.
We have calculated the chameleon pressure between two parallel plates in the presence of an intervening medium that affects the mass of the chameleon field. As intuitively expected, the gas in theExpand
Dark spinor models in gravitation and cosmology
We introduce and carefully define an entire class of field theories based on non-standard spinors. Their dominant interaction is via the gravitational field which makes them naturally dark; we referExpand
The value of the cosmological constant
We make the cosmological constant, Λ, into a field and restrict the variations of the action with respect to it by causality. This creates an additional Einstein constraint equation. It restricts theExpand
Active galactic nuclei shed light on axionlike particles.
We demonstrate that the scatter in the luminosity relations of astrophysical objects can be used to search for axionlike particles. This analysis is applied to observations of active galactic nuclei,Expand
Detecting chameleons: The astronomical polarization produced by chameleonlike scalar fields
We show that a coupling between chameleonlike scalar fields and photons induces linear and circular polarization in the light from astrophysical sources. In this context chameleonlike scalar fieldsExpand