Phenomenological analysis of quantum collapse as source of the seeds of cosmic structure

TL;DR

This paper explores a phenomenological approach to quantum collapse as the origin of cosmic structure, proposing new collapse schemes inspired by quantum gravity ideas to better match observed spectra.

Contribution

It introduces an alternative collapse scheme based on Wigner functional correlations, addressing shortcomings in previous models of quantum collapse during inflation.

Findings

The new collapse scheme can produce a spectrum closer to observations.

Comparison of different collapse schemes shows varying degrees of spectral agreement.

The approach links quantum gravity ideas with cosmological structure formation.

Abstract

The standard inflationary version of the origin of the cosmic structure as the result of the quantum fluctuations during the early universe is less than fully satisfactory as has been argued in [A. Perez, H. Sahlmann, and D. Sudarsky, Class. Quantum Grav., 23, 2317, (2006)]. A proposal is made there of a way to address the shortcomings by invoking a process similar to the collapse of the quantum mechanical wave function of the various modes of the inflaton field. This in turn was inspired on the ideas of R. Penrose about the role that quantum gravity might play in bringing about such breakdown of the standard unitary evolution of quantum mechanics. In this paper we study in some detail the two schemes of collapse considered in the original work together with an alternative scheme, which can be considered as "more natural" than the former two. The new scheme, assumes that the collapse follows the correlations indicated in the Wigner functional of the initial state. We end with considerations regarding the degree to which the various schemes can be expected to produce a spectrum that resembles the observed one.