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Disformally coupled inflation
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.ORCID iD: 0000-0002-9403-8565
2016 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, Vol. 2016, no 3, 006Article in journal (Refereed) PublishedText
Abstract [en]

A disformal coupling between two scalar fields is considered in the context of cosmological inflation. The coupling introduces novel derivative interactions mixing the kinetic terms of the fields but without introducing superluminal or unstable propagation of the two scalar fluctuation modes. Though the typical effect of the disformal coupling is to inhibit one of the fields from inflating the universe, the energy density of the other field can drive viable near Sitter -inflation in the presence of nontrivial disformal dynamics, in particular when one assumes exponential instead of power-law form for the couplings. The linear perturbation equations are written for the two-field system, its canonical degrees of freedom are quantised, their spectra are derived and the inflationary predictions are reported for numerically solved exponential models. A generic prediction is low tensor-to-scalar ratio.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2016. Vol. 2016, no 3, 006
Keyword [en]
cosmology with extra dimensions, ination, physics of the early universe, string theory and cosmology
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-187273DOI: 10.1088/1475-7516/2016/03/006ISI: 000375608200008ScopusID: 2-s2.0-84961730778OAI: oai:DiVA.org:kth-187273DiVA: diva2:929728
Note

QC 20160519

Available from: 2016-05-19 Created: 2016-05-19 Last updated: 2016-06-08Bibliographically approved

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Koivisto, Tomi
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Nordic Institute for Theoretical Physics NORDITA
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