期刊
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
卷 -, 期 12, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/1475-7516/2012/12/036
关键词
inflation; non-gaussianity
资金
- US DOE [DE-AC02-765F00515]
- DOE [DE-FG02-90ER40542]
- Monell Foundation
- Grant for Support of Scientific Schools [NSh-3035.2008.2]
- Mark Leslie graduate award
- [RFBR 07-02-00878]
We apply the Effective Field Theory of Inflation to study the case where the continuous shift symmetry of the Goldstone boson pi is softly broken to a discrete subgroup. This case includes and generalizes recently proposed String Theory inspired models of Inflation based on Axion Monodromy. The models we study have the property that the 2-point function oscillates as a function of the wavenumber, leading to oscillations in the CMB power spectrum. The non-linear realization of time diffeomorphisms induces some self-interactions for the Goldstone boson that lead to a peculiar non-Gaussianity whose shape oscillates as a function of the wavenumber. We find that in the regime of validity of the effective theory, the oscillatory signal contained in the n-point correlation functions, with n > 2, is smaller than the one contained in the 2-point function, implying that the signature of oscillations, if ever detected, will be easier to find first in the 2-point function, and only then in the higher order correlation functions. Still the signal contained in higher-order correlation functions, that we study here in generality, could be detected at a subleading level, providing a very compelling consistency check for an approximate discrete shift symmetry being realized during inflation.
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