Franco Fiorini

Modified teleparallel gravity: Inflation without an inflaton

The Born-Infeld strategy to smooth theories having divergent solutions is applied to the teleparallel equivalent of general relativity. Differing from other theories of modified gravity, modified teleparallelism leads to second order equations, since the teleparallel Lagrangian only contains first derivatives of the vierbein. We show that the Born-Infeld-modified teleparallelism solves the particle horizon problem in a spatially flat Friedmann-Robertson-Walker (FRW) universe by providing an initial exponential expansion without resorting to an inflaton field.

Born-Infeld gravity in Weitzenböck spacetime

Fil: Ferraro, Rafael. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Astronomia y Fisica del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomia y Fisica del Espacio; Argentina

Non trivial frames for f(T) theories of gravity and beyond

Abstract Some conceptual issues concerning f ( T ) theories – a family of modified gravity theories based on absolute parallelism – are analyzed. Due to the lack of local Lorentz invariance, the autoparallel frames satisfying the field equations are evasive to an a priori physical understanding. We exemplify this point by working out the vierbein (tetrad) fields for closed and open Friedmann–Robertson–Walker cosmologies.

Spherically symmetric static spacetimes in vacuum f(T) gravity

We show that Schwarzschild geometry remains as a vacuum solution for those four-dimensional

COSMOLOGICAL FRAMES FOR THEORIES WITH ABSOLUTE PARALLELISM

f(T)

A Type of Born-Infeld regular gravity and its cosmological consequences

gravitational theories behaving as ultraviolet deformations of general relativity. In the gentler context of three-dimensional gravity, we also find that the infrared-deformed

Remnant group of local Lorentz transformations in

f(T)

\mathcal{f}(T)

gravities, like the ones used to describe the late cosmic speed up of the Universe, have as the circularly symmetric vacuum solution a Deser-de Sitter or a Ba\~nados, Teitelboim and Zanelli-like spacetime with an effective cosmological constant depending on the infrared scale present in the function

theories

f(T)

Born–Infeld determinantal gravity and the taming of the conical singularity in 3-dimensional spacetime

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