Related papers: A search for chameleon particles using a photon re…
Photon regeneration experiments searching for signatures of oscillations of photons into hypothetical very weakly interacting ultra-light particles, such as axions, axion-like and hidden-sector particles, have improved their sensitivity…
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 the dichroism and the birefringence induced…
It is generally accepted that certain astronomical and cosmological observations can be explained by invoking the concepts of Dark Matter and Dark Energy (DM/DE). Applying straightforward extensions of the Standard Model to DM/DE, results…
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…
In chameleon dark energy models, local gravity constraints tend to rule out parameters in which observable cosmological signatures can be found. We study viable chameleon potentials consistent with a number of recent observational and…
Certain scalar-tensor theories exhibit the so-called chameleon mechanism, whereby observational signatures of scalar fields are hidden by a combination of self-interactions and interactions with ambient matter. Not all scalar-tensor…
Light scalar fields are expected to arise in theories of high energy physics (such as string theory), and find phenomenological motivations in dark energy, dark matter, or neutrino physics. However, the coupling of light scalar fields to…
Dark matter particles may interact with other dark matter particles via a new force mediated by a dark photon, $A^{\prime}$, which would be the dark-sector analog to the ordinary photon of electromagnetism. The dark photon can obtain a…
Chameleon dark energy models are a popular alternative to the standard cosmological constant model. These models consist of a new light degree of freedom, called chameleon, with a density dependent mass and a non-trivial coupling to both…
Dark matter in the form of particles from a hidden mirror sector has recently been proposed as an explanation for the DAMA annual modulation signal. Here one assumes that there exists a small mixing between photons and mirror photons. We…
We compute bounds from atomic spectroscopy on chameleon fields that couple to the photon. Chameleons are a wide class of scalar field models that generically lead to screened fifth forces and a host of novel phenomenologies, particularly…
Chameleon fields are scalar fields whose mass depends on the ambient matter density. We investigate the effects of these fields on the growth of density perturbations on sub-galactic scales and the formation of the first dark matter halos.…
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.…
The dark photon is a new gauge boson that naturally arises in many beyond the Standard Model theoretical models, featuring interactions that resemble quantum electrodynamics. Due to this feature, it is often considered the portal between…
Magnetic fields observed across cosmic scales are difficult to explain within conventional physics. A primordial origin is, thus, often assumed. While a nonminimal coupling of the inflaton with the electromagnetic field could theoretically…
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…
We show that the chameleon scalar field can drive the current phase of cosmic acceleration for a large class of scalar potentials that are also consistent with local tests of gravity. These provide explicit realizations of a quintessence…
Observational evidence implying the accelerated expansion of the universe has been the motivation to develop various classes of modified gravity theories. One of them uses the so-called "screening mechanism", which is successful in…
In the present work we examine the possibility of detecting light dark matter particles (WIMP) utilizing their possible interactions with the electrons. Employing reasonable theoretical models we evaluate the expected event rates in the…
The existence of a new, photon-like, massive particle, the gamma' or dark photon, is postulated in several extensions of the Standard Model. These models are often advocated to explain some recent puzzling astrophysical observations, as…