Related papers: Constraining chameleon field theories using the Ga…
Toward understanding of dark energy, we propose a novel method to directly produce a chameleon particle and force its decay under controlled gas pressure in a laboratory-based experiment. {\it Chameleon gravity}, characterized by its…
Chameleon scalar fields are dark energy candidates which suppress fifth forces in high density regions of the universe by becoming massive. We consider chameleon models as effective field theories and estimate quantum corrections to their…
We investigate the cosmological dynamics of a class of supersymmetric chameleon models coupled to cold dark matter fermions. Supergravity corrections ensure that these models are efficiently screened in all astrophysical objects of…
The chameleon scalar field is considered as a possible cause of accelerated expansion of the Universe. The chameleon field induces an interaction potential between a particle and a massive body. Previous experiments with falling cold…
We present a cursory overview of chameleon models of dark energy and their laboratory tests with an emphasis on optical and Casimir experiments. Optical experiments measuring the ellipticity of an initially polarised laser beam are…
Current acceleration of the cosmic expansion leads to coincidence as well as fine-tuning issues in the framework of general relativity. Dynamical scalar fields have been introduced in response of these problems, some of them invoking…
We analyse the PVLAS results using a chameleon field whose properties depend on the environment. We find that, assuming a runaway bare potential $V(\phi)$ and a universal coupling to matter, the chameleon potential is such that the scalar…
The chameleon mechanism appearing in massive tensor-scalar theory of gravity can effectively reduce the nonminimal coupling between the scalar field and matter. This mechanism is invoked to reconcile cosmological data requiring introduction…
We extend the chameleon models by considering Scalar-Fluid theories where the coupling between matter and the scalar field can be represented by a quadratic effective potential with density-dependent minimum and mass. In this context, we…
We review the tantalising prospect that the first evidence for the dark energy driving the observed acceleration of the Universe on giga-parsec scales may be found through metre scale laboratory based atom interferometry experiments. To do…
Dark energy models, such as the chameleon, where the acceleration of the expansion of the universe results from the dynamics of a scalar field coupled to matter, suffer from the potential existence of a fifth force. Three known mechanisms…
The mass of a scalar field mediating a fifth force is tightly constrained by experiments. We show, however, that adding a quartic self-interaction for such a scalar makes most tests much less constraining: the non-linear equation of motion…
We report on a new search for solar chameleons with the CERN Axion Solar Telescope (CAST). A GridPix detector was used to search for soft X-ray photons in the energy range from 200 eV to 10 keV from converted solar chameleons. No…
Chameleon scalar field is a new model, which introduced to provide a mechanism for exhibiting accelerating universe. Chameleon field has several interesting aspects, such as field dependence on the local matter density. For this model we…
This article is dedicated to the use the MICROSCOPE mission's data to test chameleon theory of gravity. We take advantage of the technical sessions aimed to characterize the electrostatic stiffness of MICROSCOPE's instrument intrinsic to…
Chameleon particles, which could explain dark energy, are in many ways similar to axions, suggesting that an axion helioscope can be used for chameleon detection. The distinguishing property of chameleon particles is that, unlike Standard…
We review some of the properties of chameleon theories. Chameleon fields are gravitationally coupled to matter and evade gravitational tests thanks to two fundamental properties. The first one is the density dependence of the chameleon…
The nature of dark energy is one of the most outstanding problems in physical science, and various theories have been proposed. It is therefore essential to directly verify or rule out these theories experimentally. However, despite…
Chameleons are scalar fields that couple directly to ordinary matter with gravitational strength, but which nevertheless evade the stringent constraints on tests of gravity because of properties they acquire in the presence of high ambient…
If dark energy --- which drives the accelerated expansion of the universe --- consists of a light scalar field, it might be detectable as a "fifth force" between normal-matter objects, in potential conflict with precision tests of gravity.…