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# Constraining holographic cosmology using Planck data

Afshordi, Niayesh, Gould, Elizabeth and Skenderis, Kostas (2017) Constraining holographic cosmology using Planck data. Physical Review D, 95 (12).

Record type: Article

## Abstract

Holographic cosmology offers a novel framework for describing the very early Universe in which cosmological predictions are expressed in terms of the observables of a three dimensional quantum field theory (QFT). This framework includes conventional slow-roll inflation, which is described in terms of a strongly coupled QFT, but it also allows for qualitatively new models for the very early Universe, where the dual QFT may be weakly coupled. The new models describe a universe which is non-geometric at early times. While standard slow-roll inflation leads to a (near-)power-law primordial power spectrum, perturbative superrenormalizable QFT's yield a new holographic spectral shape. Here, we compare the two predictions against cosmological observations. We use CosmoMC to determine the best fit parameters, and MultiNest for Bayesian Evidence, comparing the likelihoods. We find that the dual QFT should be non-perturbative at the very low multipoles (l ≥ 30$), while for higher multipoles (l ≤ 30$) the new holographic model, based on perturbative QFT, fits the data just as well as the standard power-law spectrum assumed in ΛCDM cosmology. This finding opens the door to applications of non-perturbative QFT techniques, such as lattice simulations, to observational cosmology on gigaparsec scales and beyond.

Text PRD-v2 - Accepted Manuscript

Accepted/In Press date: 12 May 2017
e-pub ahead of print date: 7 June 2017
Organisations: Applied Mathematics

## Identifiers

Local EPrints ID: 409590
URI: https://eprints.soton.ac.uk/id/eprint/409590
ISSN: 1550-7998
PURE UUID: c63a4384-f23e-4b31-8484-dde512a38e05

## Catalogue record

Date deposited: 31 May 2017 04:01

## Contributors

Author: Niayesh Afshordi
Author: Elizabeth Gould