Anisotropic Trispectrum of Curvature Perturbations Induced by Primordial Non-Abelian Vector Fields - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




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Abstract: Motivated by the interest in models of the early universe where statisticalisotropy is broken and can be revealed in cosmological observations, weconsider an SU2 theory of gauge interactions in a single scalar fieldinflationary scenario. We calculate the trispectrum of curvature perturbations,as a natural follow up to a previous paper of ours, where we studied thebispectrum in the same kind of models. The choice of a non-Abelian set-up turnsout to be very convenient: on one hand, gauge boson self-interactions can bevery interesting being responsible for extra non-trivial terms naturallyabsent in the Abelian case appearing in the cosmological correlationfunctions; on the other hand, its results can be easily reduced to the U1case. As expected from the presence of the vector bosons, preferred spatialdirections arise and the trispectrum reveals anisotropic signatures. Weevaluate its amplitude tau {NL}, which receives contributions both from scalarand 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 shapeanalysis of the trispectrum; in particular we discuss, with some examples, howthe anisotropy parameters appearing in the analytic expression of thetrispectrum can modulate its profile and we show that the amplitude of theanisotropic part of the trispectrum can be of the same order of magnitude asthe isotropic part.



Autor: Nicola Bartolo, Emanuela Dimastrogiovanni, Sabino Matarrese, Antonio Riotto

Fuente: https://arxiv.org/







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