Non-Standard Hierarchies of the Runnings of the Spectral Index in Inflation
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 mode...
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| Format: | Article |
| Language: | English |
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MDPI AG
2017-03-01
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| Series: | Universe |
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| Online Access: | http://www.mdpi.com/2218-1997/3/1/17 |
| Summary: | 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. |
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| ISSN: | 2218-1997 |