Anisotropic trispectrum of curvature perturbations induced by primordial non-Abelian vector fields

Motivated by the interest in models of the early universe where statistical isotropy is broken and can be revealed in cosmological observations, we consider an SU(2) theory of gauge interactions in a single scalar field inflationary scenario. We calculate the trispectrum of curvature perturbations,...

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Bibliographic Details
Published in:Journal of cosmology and astroparticle physics 2009-11, Vol.2009 (11), p.028-28
Main Authors: Bartolo, Nicola, Dimastrogiovanni, Emanuela, Matarrese, Sabino, Riotto, Antonio
Format: Article
Language:English
Subjects:
ANISOTROPY
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CORRELATION FUNCTIONS
DISTURBANCES
INFLATIONARY UNIVERSE
SCALAR FIELDS
SU-2 GROUPS
U-1 GROUPS
UNIVERSE
VECTOR FIELDS
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Summary:Motivated by the interest in models of the early universe where statistical isotropy is broken and can be revealed in cosmological observations, we consider an SU(2) theory of gauge interactions in a single scalar field inflationary scenario. We calculate the trispectrum of curvature perturbations, as a natural follow up to a previous paper of ours, where we studied the bispectrum in the same kind of models. The choice of a non-Abelian set-up turns out to be very convenient: on one hand, gauge boson self-interactions can be very interesting being responsible for extra non-trivial terms (naturally absent in the Abelian case) appearing in the cosmological correlation functions; on the other hand, its results can be easily reduced to the U(1) case. As expected from the presence of the vector bosons, preferred spatial directions arise and the trispectrum reveals anisotropic signatures. We evaluate its amplitude τ{sub NL}, which receives contributions both from scalar and vector fields, and verify that, in a large subset of its parameter space, the latter contributions can be larger than the former. We carry out a shape analysis of the trispectrum; in particular we discuss, with some examples, how the anisotropy parameters appearing in the analytic expression of the trispectrum can modulate its profile and we show that the amplitude of the anisotropic part of the trispectrum can be of the same order of magnitude as the isotropic part.
ISSN:1475-7516
1475-7516
DOI:10.1088/1475-7516/2009/11/028