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Resonant non-Gaussianity

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If you have a question about this talk, please contact James Fergusson.

Two of the most exciting observables in the cosmic microwave background (CMB) radiation, which could deeply impact our picture of the early universe, are non-Gaussianity and tensor modes. A potential detection of tensor modes can be explained in terms of a model of large field inflation. Theoretical considerations suggest that a symmetry should be invoked in order to protect the flatness of the inflaton potential and hence an axion enjoying a shift symmetry is a natural candidate. As main example, I will present a model of inflation in string theory based on axion monodromy. Non-perturbative effects typically correct the axion potential leading to small sinusoidal modulations on top of an otherwise flat slow roll potential. It can be shown analytically that a resonance between the oscillations of the background and the oscillations of the curvature fluctuations is responsible for the production of an observably large non-Gaussian signal. An explicit expression for the shape of this resonant non-Gaussianity is presented. There is essentially no overlap between this shape and the local, equilateral, and orthogonal shapes, and in fact resonant non-Gaussianity is not captured by the simplest version of the effective field theory of inflation. Hopefully the analytic expression for resonant non-Gaussianity will be useful to further observationally constrain this class of models.

This talk is part of the DAMTP Friday GR Seminar series.

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