Gravitational Higgs Mechanism in Neutron Star Interiors
  We suggest that nonminimally coupled scalar fields can lead to modifications of the microphysics in the interiors of relativistic stars. As a concrete example, we consider the generation of a non-zero photon mass in such high-density environments. This is achieved by means of a light gravitational scalar, and the scalarization phase transition in scalar-tensor theories of gravitation. Two distinct models are presented, and phenomenological implications are briefly discussed. 
Andrew Coates, Michael W. Horbartsch, Thomas P. Sotiriou
gr-qc astro-ph.HE hep-th