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Exponential quintessence: curved, steep and stringy?
Journal of High Energy Physics, Volume: 2024, Issue: 8, Start page: 117
Swansea University Author:
Ivonne Zavala Carrasco
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DOI (Published version): 10.1007/jhep08(2024)117
Abstract
We explore the possibility that our universe’s current accelerated expansion is explained by a quintessence model with an exponential scalar potential, V = V0e−λ ϕ, keeping an eye towards λ ≥ √2 and an open universe, favorable to a string theory realisation and with no cosmological horizon. We work...
Published in: | Journal of High Energy Physics |
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ISSN: | 1029-8479 |
Published: |
Springer Science and Business Media LLC
2024
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Online Access: |
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URI: | https://cronfa.swan.ac.uk/Record/cronfa68372 |
Abstract: |
We explore the possibility that our universe’s current accelerated expansion is explained by a quintessence model with an exponential scalar potential, V = V0e−λ ϕ, keeping an eye towards λ ≥ √2 and an open universe, favorable to a string theory realisation and with no cosmological horizon. We work out the full cosmology of the model, including matter, radiation, and optionally negative spatial curvature, for all λ > 0, performing an extensive analysis of the dynamical system and its phase space. The minimal physical requirements of a past epoch of radiation domination and an accelerated expansion today lead to an upper bound λ ≲ √3, which is driven slightly up in the presence of observationally allowed spatial curvature. Cosmological solutions start universally in a kination epoch, go through radiation and matter dominated phases and enter an epoch of acceleration, which is only transient for λ > √2. Field distances traversed between BBN and today are sub-Planckian. We discuss possible string theory origins and phenomenological challenges, such as time variation of fundamental constants. We provide theoretical predictions for the model parameters to be fitted to data, most notably the varying dark energy equation of state parameter, in light of recent results from DES-Y5 and DESI. |
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Keywords: |
Cosmological models, Cosmology of Theories BSM, String and Brane Phenomenology |
College: |
Faculty of Science and Engineering |
Funders: |
We would like to thank A. Moradinezhad, V. Poulin, N. Schöneberg and G. Tringas for very helpful discussions. We also thank the organisers of the String Phenomenology 2023 Conference, that allowed interactions leading to this work. The work of S. L. P. is partially supported by the U.K. Science and Technology Facilities Council grant ST/X000699/1. The work of T. W. is supported in part by the NSF grant PHY-2210271. I. Z. is partially funded by the STFC grants ST/T000813/1 and ST/X000648/1. This research was supported in part by grant NSF PHY-2309135 to the Kavli Institute for Theoretical Physics (KITP). For the purpose of open access, the authors have applied a Creative Commons Attribution licence to any Author Accepted Manuscript version arising. |
Issue: |
8 |
Start Page: |
117 |