Dynamical torsion gravity backgrounds

Abstract

We write the field equations of torsion gravity theories and the Noether identity they obey directly in terms of metric and contorsion tensor components expressed with respect to natural coordinates, i.e., without using vierbien but Lagrange multipliers. Then we obtain explicit solutions of these equations, under specific ans\"atze for the contorsion field, by assuming the metric to be respectively of the Bertotti-Robinson, pp-wave, Friedmann-Lema\^{\i}tre-Robertson-Walker or static spherically symmetric type. Among these various solutions we obtain some of them have their contorsion tensor depending on arbitrary functions that did not influence their geometry. This raises questions about the predictability of the theory.