Bouncing cosmologies via modified gravity in the ADM formalism: Application to Loop Quantum Cosmology

Understand

We consider the ADM formalism as a tool to build bouncing cosmologies.

• In this approach, the foliation of the spacetime has to be fixed in order to go beyond General Relativity modifying the gravitational sector.
• Once a preferred slicing, which we choose based on the matter content of the universe following the spirit of Weyl's postulate, has been fixed, $f$ theories depending on the extrinsic and intrinsic curvature of the slicing are covariant for all the reference frames preserving the foliation, i.e., the constraint and dynamical equations have the same form for all these observers.
• Moreover, choosing multivalued $f$ functions, bouncing backgrounds emerge in a natural way.