Nonsingular electrovacuum solutions with dynamically generated cosmological constant

Abstract

We consider static spherically symmetric configurations in a Palatini extension of General Relativity including R 2 and Ricci-squared terms, which is known to replace the central singularity by a wormhole in the electrovacuum case. We modify the matter sector of the theory by adding to the usual Maxwell term a nonlinear electromagnetic extension which is known to implement a confinement mechanism in flat space. One feature of the resulting theory is that the non-linear electric field leads to a dynamically generated cosmological constant. We show that with this matter source the solutions of the model are asymptotically de Sitter and possess a wormhole topology. We discuss in some detail the conditions that guarantee the absence of singularities and of traversable wormholes.

Wormholes and nonsingular spacetimes in Palatinif(R)gravity

“…This property is not unique of four dimensional models and persists in higher dimensional scenarios [24,38]. We also note that the same models that remove the point-like singularity in black holes, also produce nonsingular cosmologies where the Big Bang singularity is replaced by a cosmic bounce [23,39].…”

Classical resolution of black hole singularities in arbitrary dimension

“…where now the role of x as a radial coordinate is apparent. This leaves a single independent equation for A(x), which from (A15) and (34) reads…”

Born-Infeldf(R)gravity

“…In this sense, as advanced above, the BI gravity Lagrangian yields a low-energy perturbative expansion with GR as the lowest order followed by quadratic and higher-order curvature corrections with specific coefficients, which is in consonance with the expected quantum field theory corrections at high energies. Theories of this type, with up to quadratic curvature corrections, have been investigated within the Palatini approach in the literature [57,58,59,60,61,62,63], and specific methods to deal with the resulting field equations have been developed [64]. However, higher-order curvature corrections involving cubic powers or higher of the Ricci tensor (such as R µα R βγ R δν g αβ g γδ g µν , for instance) have not been explored yet and are likely to require new methods.…”