Cosmological perturbations in modified teleparallel gravity models

TL;DR

This paper derives and analyzes linear cosmological perturbation equations in modified teleparallel gravity models, highlighting features and generalizations relevant for understanding structure formation in these theories.

Contribution

It provides the first comprehensive derivation of linear perturbation equations in $f(T)$ and scalar-torsion $f()$ models, including analysis of various limits and generalizations.

Findings

Derived full linear perturbation equations for $f(T)$ and $f()$ models.

Identified interesting features in generalizations to other models and backgrounds.

Discussed implications for cosmological structure formation.

Abstract

Cosmological perturbations are considered in $f(T)$ and in scalar-torsion $f(\varphi)T$ teleparallel models of gravity. Full sets of linear perturbation equations are accurately derived and analysed at the relevant limits. Interesting features of generalisations to other teleparallel models, spatially curved backgrounds, and rotated tetrads are pointed out.