The Primordial Trispectrum Through a Bounce: tauNL and gNL Against the Planck Bound
Year: 2026
Type: article
Abstract: The four-point function of the primordial perturbations tests the structure of the generating mechanism in ways the bispectrum cannot, because its two standard amplitudes respond differently to single-source and multi-source generation. This paper computes both for perturbations transmitted through a torsion-regulated bounce. The single-source consistency value implied by the local bispectrum is tauNL = 4.72. The direct matching calculation gives a larger value, tauNL = 43.4, because mode mixing across the bounce correlates pairs of modes that a single-source model would leave independent. Both lie far below the Planck bound of 2800, with the direct value a factor 64 under it. The cubic amplitude is gNL = -5215. The gap between the consistency value and the direct value is the informative product: it measures the multi-mode character of bounce generation, and any future trispectrum measurement near the direct value, rather than the consistency value, would identify matching physics rather than a single rolling source as the origin of the perturbations. The study is computed from stated assumptions, not measured.
Author: Aldred, William Alexander
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225819062
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