Metric-Affine Gravity as an Effective Field Theory

Understand

We discuss theories of gravity with independent metric (or frame field) and connection, from the point of view of effective field theory.

• We count the parity-even Lagrangian terms of dimension up to four and give explicit bases for the independent terms that contribute to the two-point function.
• We then give the decomposition of the linearized action on a complete basis of spin projectors and consider various subclasses of Metric-Affine Gravity theories (MAGs).
• We show that teleparallel theories can be dynamically equivalent to any metric theory of gravity and give the particle content of those whose Lagrangian contains only dimension-two terms.