de Sitter, alpha `-corrections & duality invariant cosmology

Krishnan, Chethan (2019) de Sitter, alpha `-corrections & duality invariant cosmology. In: JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS (10).

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Abstract

Demanding O(d, d)-duality covariance, Hohm and Zwiebach have written down the action for the most general cosmology involving the metric, b-field and dilaton, to all orders in alpha' in the string frame. Remarkably, for an FRW metric-dilaton ansatz the equations of motion turn out to be quite simple, except for the presence of an unknown function of a single variable. If this unknown function satisfies some simple properties, it allows de Sitter solutions in the string frame. In this note, we write down the Einstein frame analogues of these equations, and make some observations that make the system tractable. Perhaps surprisingly, we find that a necessary condition for de Sitter solutions to exist is that the unknown function must satisfy a certain second order non-linear ODE. The solutions of the ODE do not have a simple power series expansion compatible with the leading supergravity expectation. We discuss possible interpretations of this fact. After emphasizing that all (potential) string and Einstein frame de Sitter solutions have a running dilaton, we write down the most general cosmologies with a constant dilaton in string/Einstein frame: these have power law scale factors.

Item Type:	Journal Article
Publication:	JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
Publisher:	IOP PUBLISHING LTD
Additional Information:	Copyright of this article belongs to IOP PUBLISHING LTD
Keywords:	dark energy theory; string theory and cosmology
Department/Centre:	Division of Physical & Mathematical Sciences > Centre for High Energy Physics
Date Deposited:	10 Jan 2020 06:12
Last Modified:	10 Jan 2020 06:12
URI:	http://eprints.iisc.ac.in/id/eprint/64309

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