Constraining quantum collapse inflationary models with CMB data

TL;DR

This paper tests models of quantum wave function collapse during inflation against Planck CMB data, finding that one collapse scheme fits as well as standard cosmology, while another is slightly disfavored.

Contribution

It performs a Bayesian comparison of two quantum collapse models within a quasi-de Sitter inflationary scenario using recent CMB data.

Findings

One collapse model matches the standard $ ext{Λ}$CDM Bayesian evidence.

The other collapse model is weakly disfavored compared to standard cosmology.

Results suggest potential observational signatures of quantum collapse in CMB data.

Abstract

The hypothesis of the self-induced collapse of the inflaton wave function was proposed as responsible for the emergence of inhomogeneity and anisotropy at all scales. This proposal was studied within an almost de Sitter space-time approximation for the background, which led to a perfect scale-invariant power spectrum, and also for a quasi-de Sitter background, which allows to distinguish departures from the standard approach due to the inclusion of the collapse hypothesis. In this work we perform a Bayesian model comparison for two different choices of the self-induced collapse in a full quasi-de Sitter expansion scenario. In particular, we analyze the possibility of detecting the imprint of these collapse schemes at low multipoles of the anisotropy temperature power spectrum of the Cosmic Microwave Background (CMB) using the most recent data provided by the Planck Collaboration. Our results show that one of the two collapse schemes analyzed provides the same Bayesian evidence of the minimal standard cosmological model $\Lambda$CDM, while the other scenario is weakly disfavoured with respect to the standard cosmology.