Bimetric-Affine Quadratic Gravity

Understand

Bimetric gravity, is a theory of gravity that posits the existence of two interacting and dynamical metric tensors.

• The spectrum of bimetric gravity consists of a massless and a massive spin-2 particle.
• The form of the interactions between the two metrics $g_{\mu\nu}$ and $f_{\mu\nu}$ is constrained by requiring absence of the so called Boulware-Deser ghost.
• In this work we extend the original bimetric theory to its bimetric-affine counterpart, in which the two connections, associated with the Ricci scalars, are treated as independent variables.