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Exponential suppression of the cosmological constant in nonsupersymmetric string vacua at two loops and beyond

Abel, Steven; Stewart, Richard J.

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Authors

Richard J. Stewart



Abstract

Two independent criteria are presented that together guarantee exponential suppression of the two-loop cosmological constant in nonsupersymmetric heterotic strings. They are derived by performing calculations in both the full string theory and in its effective field theory, and come respectively from contributions that involve only physical untwisted states, and contributions that include orbifold twisted states. The criteria depend purely on the spectrum and charges, so a model that satisfies them will do so with no fine-tuning. An additional consistency condition (emerging from the so-called separating degeneration limit of the two-loop diagram) is that the one-loop cosmological constant must also be suppressed, by Bose-Fermi degeneracy in the massless spectrum. We comment on the effects of the residual exponentially suppressed one-loop dilaton tadpole, with the conclusion that the remaining instability would be under perturbative control in a generic phenomenological construction. We remark that theories of this kind, that have continued exponential suppression to higher orders, can form the basis for a string implementation of the “naturalness without supersymmetry” idea.

Citation

Abel, S., & Stewart, R. J. (2017). Exponential suppression of the cosmological constant in nonsupersymmetric string vacua at two loops and beyond. Physical Review D, 96(10), Article 106013. https://doi.org/10.1103/physrevd.96.106013

Journal Article Type Article
Acceptance Date Oct 19, 2017
Online Publication Date Nov 17, 2017
Publication Date Nov 17, 2017
Deposit Date Nov 27, 2017
Publicly Available Date Mar 29, 2024
Journal Physical Review D
Print ISSN 2470-0010
Electronic ISSN 2470-0029
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 96
Issue 10
Article Number 106013
DOI https://doi.org/10.1103/physrevd.96.106013
Related Public URLs https://arxiv.org/abs/1701.06629

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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.





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