Spontaneous scalarization: asymmetron as dark matter
  We propose a new scalar-tensor model which induces significant deviation from
general relativity inside dense objects like neutron stars, while passing
solar-system and terrestrial experiments, extending a model proposed by Damour
and Esposito-Farese. Unlike their model, we employ a massive scalar field
dubbed asymmetron so that it not only realizes proper cosmic evolution but also
can account for the cold dark matter. In our model, asymmetron undergoes
spontaneous scalarization inside dense objects, which results in reduction of
the gravitational constant by a factor of order unity. This suggests that
observational tests of constancy of the gravitational constant in high density
phase are the effective ways to look into the asymmetron model.
