http://arxiv.org/abs/1705.01072
We consider the variational principle in the covariant formulation of modified teleparallel theories with second order field equations. We show that the variational problem is consistent and leads to non-trivial modifications of teleparallel gravity only if the spin connection is chosen in a such way that the action is finite. Since this is achieved by introducing the second reference tetrad into the theory, modified teleparallel theories effectively become bigravity theories with two tetrads, where the second tetrad corresponds to the non-dynamical, “reference”, metric tensor and generates the connection. We then discuss the relation of our results and those obtained in the usual, non-covariant, formulation of teleparallel theories.
M. Krssak
Wed, 3 May 17
13/60
Comments: 14 pages, comments are welcomed
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