A non-Gaussian landscape

Who: Sami Nurmi (University of Helsinki)
When: Friday, January 25, 2013 at 14:15
Where: U49

 

Primordial perturbations with wavelengths greater than the observable universe shift the effective background fields in our observable patch from their global averages over the inflating space. This leads to a landscape picture where the properties of our observable patch depend on its location and may significantly differ from the expectation values predicted by the underlying fundamental inflationary model. I will demonstrate that if multiple fields are present during inflation, this may happen even if our horizon exit would be preceded by only a few e-foldings of inflation. Non-Gaussian statistics are especially affected: for example models of local non-Gaussianity predicting |f_NL| >> 10 over the entire inflating volume can have a probability up to a few tens of percent to generate a non-detectable bispectrum in our observable patch |fNL^{obs.}| <10. I will explore the connection between the observable local primordial perturbations and global properties of the inflating space which reflect the underlying high energy physics. I will discuss the implications of both a detection and non-detection of primordial non-Gaussianity by Planck, and provide new insights on the naturalness of different observational configurations.

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