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)|
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|State||Published - Dec 23 2015|
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)