|Speaker:||Raphael Flauger (Yale)|
|Title:||Resonant Non-Gaussianity from Axion Monodromy Inflation|
|Date (JST):||Thu, Sep 02, 2010, 13:00 - 14:00|
|Place:||Seminar Room A|
The study of the anisotropies in the cosmic microwave background radiation over the past two decades has provided us with important information about the early universe. There is strong evidence that these anisotropies were generated long before the cosmic microwave radiation was emitted. The most commonly studied possibility is that they originated as quantum fluctuations during a period of rapid expansion of the universe called inflation. In addition to a spectrum of scalar perturbations consistent with the one that has been observed, inflation also predicts the presence of gravitational waves, which might be observable in the polarization of the cosmic microwave background. An observation of this signal would indicate that the inflaton must have traversed a super-Planckian distance. Realizing this in string theory has been challenging.
After reviewing the basic observables relevant for the study of the cosmic microwave background, I will describe the basic ingredients for a string theoretic model in which the inflaton can move over a super-Planckian distance, leading to an observable gravitational wave signal within string theory.
In addition to an observable tensor signal, the model may also lead to other interesting signatures such as modulations in the power spectrum of scalar perturbations and/or an interesting shape of non-Gaussianities.
I will give a derivation of this type of non-Gaussianities and show that they are orthogonal to the shapes that have been looked for in the data so far. There are thus no experimental constraints on this type of non-Gaussianity, and the signal might be waiting to be discovered.