General teleparallel modifications of Schwarzschild geometry

Teleparallel theories of gravity are described in terms of the tetrad of a metric and a flat connection with torsion. In this paper, we study spherical symmetry in a modified teleparallel theory of gravity which is based on an arbitrary function of the five possible scalars constructed from the irreducible parts of torsion. This theory is a generalisation of the so-called New General Relativity theory. We find that only two scalars are different to zero in spherical symmetry and we solve the corresponding field equations analytically for conformal Teleparallel gravity, and then perturbatively around Schwarzschild geometry for the general perturbative theory around GR. Finally we compute phenomenological effects from the perturbed solutions such as the photon sphere, perihelion shift, Shapiro delay and the light deflection. We find their correspondent correction to the standard GR contribution and their dependence on the three model parameters.