Small cosmological signatures from multi-brane models

TL;DR

This paper investigates multi-brane inflation models with moduli stabilization, analyzing their potential observable signatures in the CMB, but finds these signals are too weak to detect with current or future experiments.

Contribution

It provides a detailed analysis of the signatures of multi-brane inflation models with evolving volume moduli, highlighting their sensitivity to field trajectories and the challenge of observability.

Findings

Signatures depend heavily on field trajectories.

Predicted signals are below current detection thresholds.

Even future experiments are unlikely to observe these signatures.

Abstract

We analyse the signatures of brane inflation models with moduli stabilisation. These are hybrid inflation models with a non-trivial field-space metric which can induce complex trajectories for the fields during inflation. This in turn could lead to observable features on the power spectrum of the CMB fluctuations through departures from near scale invariance or the presence of isocurvature modes. We look specifically at multi-brane models in which the volume modulus also evolves. We find that the signatures are highly sensitive to the actual trajectories in field space, but their amplitudes are too small to be observable even for future high precision CMB experiments.