Evading the Lyth bound in hybrid natural inflation
نویسندگان
چکیده
منابع مشابه
Evading 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...
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• 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...
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We derive an extended version of the well-known Lyth Bound on the total variation of the inflaton field, incorporating higher order corrections in slow roll. We connect the field variation ∆φ to both the spectral index of scalar perturbations and the amplitude of tensor modes. We then investigate the implications of this bound for “small field” potentials, where the field rolls off a local maxi...
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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...
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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: 2013
ISSN: 1550-7998,1550-2368
DOI: 10.1103/physrevd.88.123506