Cosmology and Stability in Scalar-Tensor bigravity

Understand

The bigravity models coupled with two scalar fields are constructed.

• We show that a wide class of the expansion history of the universe, especially corresponding to dark energy and/or inflation, can be described by a solution of the bigravity model.
• We discuss the stability of the solution and give the conditions for the stability.
• We also explicitly construct a model which gives a stable solution.