Lorentz gauge-invariant variables in torsion-based theories of gravity

Understand

General relativity dynamics can be derived from different actions -- which depart from the Einstein-Hilbert action in boundary terms -- and for different choices of the dynamical variables.

• Among them, the teleparallel equivalent of general relativity is a torsion-based theory for the tetrad field.
• More general torsion-based theories have been built in the last years, intending to supersede general relativity.
• There are two current ways to formulate such theories; one includes a spin-connection and the other does not.