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Bound on largest r <∼ 0.1 from sub-Planckian excursions of inflaton
, Anupam Mazumdar
Published in
Volume: 2015
Issue: 1
In this paper we will discuss the range of large tensor to scalar ratio, r, obtainable from a sub-Planckian excursion of a single, slow roll driven inflaton field. In order to obtain a large r for such a scenario one has to depart from a monotonic evolution of the slow roll parameters in such a way that one still satisfies all the current constraints of, such as the scalar amplitude, the tilt in the scalar power spectrum, running and running of the tilt close to the pivot scale. Since the slow roll parameters evolve non-monotonically, we will also consider the evolution of the power spectrum on the smallest scales, i.e. at s (k ∼ 1016 Mpc-1)<∼ 10-2, to make sure that the amplitude does not become too large. All these constraints tend to keep the tensor to scalar ratio, r <∼ 0.1. We scan three different kinds of potential for supersymmetric flat directions and obtain the benchmark points which satisfy all the constraints. We also show that it is possible to go beyond r >∼ 0.1 provided we relax the upper bound on the power spectrum on the smallest scales.
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