Next Article in Journal / Special Issue
Dark Energy and Spacetime Symmetry
Previous Article in Journal / Special Issue
Infinitesimal Structure of Singularities
Article Menu
Issue 1 (March) cover image

Export Article

Open AccessArticle
Universe 2017, 3(1), 17;

Non-Standard Hierarchies of the Runnings of the Spectral Index in Inflation

School of Mathematics and Statistics, University of Sheffield, Sheffield S10 2TN, UK
Academic Editors: Mariusz P. Dabrowski, Manuel Krämer and Vincenzo Salzano
Received: 30 January 2017 / Accepted: 26 February 2017 / Published: 2 March 2017
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
View Full-Text   |   Download PDF [236 KB, uploaded 4 March 2017]


Recent analyses of cosmic microwave background surveys have revealed hints that there may be a non-trivial running of the running of the spectral index. If future experiments were to confirm these hints, it would prove a powerful discriminator of inflationary models, ruling out simple single field models. We discuss how isocurvature perturbations in multi-field models can be invoked to generate large runnings in a non-standard hierarchy, and find that a minimal model capable of practically realising this would be a two-field model with a non-canonical kinetic structure. We also consider alternative scenarios such as variable speed-of-light models and canonical quantum gravity effects and their implications for runnings of the spectral index. View Full-Text
Keywords: early universe cosmology; testing inflation; multi-field inflation early universe cosmology; testing inflation; multi-field inflation
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Longden, C. Non-Standard Hierarchies of the Runnings of the Spectral Index in Inflation. Universe 2017, 3, 17.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Universe EISSN 2218-1997 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top