### Abstract

We investigate the possible implications of the measured value of the scalar tilt ns for the tensor-to-scalar ratio r in slow-roll, single-field inflationary models. The measured value of the tilt satisfies ns-1∼1/N∗, where N∗∼60 is the number of e-folds for observationally relevant scales. If this is not a coincidence and the scaling holds for different values of N, it strongly suggests that either r is as big as 10-1 (a possibility in tension with the recent data), or smaller than 10-2 and exponentially dependent on ns. A large region of the (ns,r) plane is not compatible with this scaling.

Original language | English (US) |
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Article number | 123528 |

Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |

Volume | 92 |

Issue number | 12 |

DOIs | |

State | Published - Dec 23 2015 |

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### ASJC Scopus subject areas

- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)

### Cite this

*Physical Review D - Particles, Fields, Gravitation and Cosmology*,

*92*(12), [123528]. https://doi.org/10.1103/PhysRevD.92.123528