Compatibility of the Chameleon-Field Model with Fifth-Force Experiments, Cosmology, and PVLAS and CAST Results

We analyze 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 field can act as dark energy. Moreover, the chameleon-field model is compatible with the CERN Axion Solar Telescope results, fifth-force experiments, and cosmology.