Modified teleparallel gravity: inflation without inflaton

TL;DR

This paper introduces a modified teleparallel gravity model using a Born-Infeld approach, which naturally produces an inflationary phase in the early universe without requiring an inflaton, addressing the horizon problem.

Contribution

It presents a novel application of Born-Infeld modification to teleparallel gravity that achieves inflation without an inflaton field, maintaining second order equations.

Findings

Achieves exponential expansion without inflaton

Solves the horizon problem in flat FRW universe

Maintains second order field equations

Abstract

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