Wormholes and black universes without phantom fields in Einstein-Cartan theory

We obtain a family of regular static, spherically symmetric solutions in Einstein-Cartan theory with an electromagnetic field and a nonminimally coupled scalar field with the correct sign of kinetic energy density. At different values of its parameters, the solution, being asymptotically flat at large values of the radial coordinate, describes (i) twice asymptotically flat symmetric wormholes, (ii) asymmetric wormholes with an AdS asymptotic at the "far end," (iii) regular black holes with an extremal horizon or two simple horizons, and (iv) black universes with a de Sitter asymptotic at the far end. As in other black universe models, it is a black hole as seen by a distant observer, but beyond its horizon there is a nonsingular expanding universe. In all these cases, both the metric and the torsion are regular in the whole space. © 2016 American Physical Society

Wormholes without exotic matter in Einstein–Cartan theory

We study the possible existence of static traversable wormholes without invoking exotic matter in the framework of the Einstein–Cartan theory. A family of exact static, spherically symmetric wormhole solutions with an arbitrary throat radius, with flat or AdS asymptotic behavior, has been obtained with sources in the form of two noninteracting scalar fields with nonzero potentials. Both scalar fields are canonical (that is, satisfy the weak energy condition), one is minimally and the other nonminimally coupled to gravity, and the latter is a source of torsion. © 2015, Pleiades Publishing, Ltd

Wormholes and black universes without phantom fields in Einstein-Cartan theory

We obtain a family of regular static, spherically symmetric solutions in Einstein-Cartan theory with an electromagnetic field and a nonminimally coupled scalar field with the correct sign of kinetic energy density. At different values of its parameters, the solution, being asymptotically flat at large values of the radial coordinate, describes (i) twice asymptotically flat symmetric wormholes, (ii) asymmetric wormholes with an AdS asymptotic at the "far end," (iii) regular black holes with an extremal horizon or two simple horizons, and (iv) black universes with a de Sitter asymptotic at the far end. As in other black universe models, it is a black hole as seen by a distant observer, but beyond its horizon there is a nonsingular expanding universe. In all these cases, both the metric and the torsion are regular in the whole space. © 2016 American Physical Society

Wormholes without exotic matter in Einstein–Cartan theory

We study the possible existence of static traversable wormholes without invoking exotic matter in the framework of the Einstein–Cartan theory. A family of exact static, spherically symmetric wormhole solutions with an arbitrary throat radius, with flat or AdS asymptotic behavior, has been obtained with sources in the form of two noninteracting scalar fields with nonzero potentials. Both scalar fields are canonical (that is, satisfy the weak energy condition), one is minimally and the other nonminimally coupled to gravity, and the latter is a source of torsion. © 2015, Pleiades Publishing, Ltd