Classicalization of inflationary perturbations by collapse models in the light of BICEP2

TL;DR

This paper explores how collapse models could explain the classical nature of primordial perturbations in inflation, analyzing potential observable effects on tensor spectra in light of BICEP2 data.

Contribution

It revisits a spontaneous collapse model of classicalization, examining its impact on inflationary tensor spectra and potential observational signatures.

Findings

Collapse models can modify the tensor power spectrum.

Precise measurements of spectral index and its running can test collapse dynamics.

The model may alter the inflationary consistency relation.

Abstract

Inflationary and hence quantum origin of primordial perturbations is on a firmer ground than ever post the BICEP2 observations of primordial gravitational waves. One crucial ingredient of success of this paradigm rests on explaining the observed classicality of cosmological inhomogeinities despite their quantum origin. Although decoherence provides a partial understanding of this issue, the question of single outcome motivates the analysis of quantum collapse models in cosmological context which generically modify the dynamics of primordial perturbations and hence can leave their imprints on observables. We revisit one such recently proposed working model of classicalization by spontaneous collapse \cite{Das:2013qwa} in the light of BICEP2 observations to look for possible modifications to tensor power spectra and their implications. We show that it can potentially change the consistency relation of single-field models and a precise measurement of $n_T$ and its running could serve as a test of such dynamics in the early universe.