T-Model Inflation and Bouncing Cosmology

TL;DR

This paper explores a cosmological model with a conformally coupled scalar field that produces a bouncing universe and inflation, aligning with observations and potentially explaining low CMB power suppression.

Contribution

It introduces a T-model inflationary framework with classical bounces in a closed universe, extending previous models to include a double-bouncing scenario without quantum gravity.

Findings

The model predicts a bouncing universe consistent with classical physics.

Perturbation analysis shows agreement with CMB observations.

The scenario may explain the suppression of power at low multipoles.

Abstract

We examine the dynamics of a closed cosmology whose matter source is that of a conformally coupled scalar field with a broken ${\rm SO}(1,1)$ symmetry, which correspond to the $\alpha$-attractors proposed by Linde and Kallosh. Following a field redefinition, such models give rise to "T-model" inflationary potentials, whose dynamics provide both an inflationary phase and a classical bounce. We show that the universe can undergo bounces far from the regime of quantum gravity. We analyse perturbations on this background with particular attention given to the effects of a double-bouncing scenario (with rapid recollapse between bounces) on the long wavelength modes. We demonstrate that the predictions of such models agree well with observations and might explain the suppression of power in the low multiples of the CMB.