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- A Nearly Gaussian Hubble-patch in a non-Gaussian Universe

Local-type primordial non-Gaussianity couples

statistics of the curvature perturbation \zeta on vastly different physical

scales. Because of this coupling, statistics (i.e. the polyspectra) of \zeta in

our Hubble volume may not be representative of those in the larger universe -- that

is, they may be biased. The bias depends on the local background value of

\zeta, which includes contributions from all modes with wavelength k ~
and is therefore enhanced if the entire post-inflationary patch is large

compared with our Hubble volume. I will discuss the bias to

locally-measured statistics for general local-type non-Gaussianity. I will

discuss three examples in detail: (i) the usual fNL, gNL model, (ii) a strongly

non-Gaussian model with \zeta ~ \zeta_G^p, and (iii) two-field non-Gaussian

initial conditions. In each scenario one may generate statistics in a

Hubble-size patch that are weakly Gaussian and consistent with observations

despite the fact that the statistics in the larger, post-inflationary patch

look very different. Finally, I will present a worked example of how the

variation in local statistics arises in the curvaton scenario.

Event Type:

Seminar

Collection/Series:

Scientific Area(s):

Speaker(s):

Event Date:

Tuesday, October 8, 2013 - 11:00 to 12:30

Location:

Space Room

©2012 Perimeter Institute for Theoretical Physics