Lyth bound revisited
نویسندگان
چکیده
منابع مشابه
The Lyth Bound Revisited
We investigate the Lyth relationship between the tensor-scalar ratio, r, and the variation of the inflaton field, ∆φ, over the course of inflation. For inflationary models that produce at least 55 e-folds of inflation, there is a correlation between r and ∆φ as anticipated by Lyth, but the scatter around the relationship is huge. However, for inflationary models that satisfy current observation...
متن کاملNotes on inflation and the Lyth bound
• The tensor-to-scalar ratio measures (up to order-one constants) the distance that the inflaton field φ traveled in field space during inflation. For detectable r, this implies ∆φ ∼ MPl. This is known as the “Lyth bound.” From the effective field theory standpoint, this is surprising, since Planck-suppressed operators are expected to spoil the flatness of the potential. Thus, this suggests a m...
متن کاملSub-Planckian two-field inflation consistent with the Lyth bound
The BICEP2 observation of a large tensor-to-scalar ratio, r = 0.20 −0.05, implies that the inflaton φ in single-field inflation models must satisfy φ ∼ 10MPl in order to produce sufficient inflation. This is a problem if interaction terms suppressed by the Planck scale impose a bound φ . MPl. Here we consider whether it is possible to have successful subPlanckian inflation in the case of two-fi...
متن کاملEvading the Lyth bound in hybrid natural inflation
Generically, the gravitational-wave or tensor-mode contribution to the primordial curvature spectrum of inflation is tiny if the field range of the inflaton is much smaller than the Planck scale. We show that this pessimistic conclusion is naturally avoided in a rather broad class of small-field models. More specifically, we consider models where an axionlike shift symmetry keeps the inflaton p...
متن کاملLarge Gravitational Waves and Lyth Bound in Multi Brane Inflation
It is shown that multi M5-brane inflation in heterotic M-theory gives rise to a detectable gravitational wave power spectrum with tensor fraction r typically larger than the projected experimental sensitivity, rexp = 0.01. A measurable gravitational wave power spectrum entails a large inflationary energy scale and a super-Planckian inflaton variation. They present serious problems for particle ...
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ژورنال
عنوان ژورنال: Physical Review D
سال: 2015
ISSN: 1550-7998,1550-2368
DOI: 10.1103/physrevd.91.123532