  We propose a scenario that can naturally explain the observed dark
matter-baryon ratio in the context of bimetric theory with a chameleon field.
We introduce two additional gravitational degrees of freedom, the massive
graviton and the chameleon field, corresponding to dark matter and dark energy,
respectively. The chameleon field is assumed to be non-minimally coupled to
dark matter, i.e., the massive graviton, through the graviton mass terms. We
find that the dark matter-baryon ratio is dynamically adjusted to the observed
value due to the energy transfer by the chameleon field. As a result, the model
can explain the observed dark matter-baryon ratio independently from the
initial abundance of them.
