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arXiv · 2601.15878

The thermal backreaction of a scalar field in de Sitter spacetime. II. Spectrum enhancement and holography

Antonis Kalogirou
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Abstract

We study a spacetime obtained from the semi-classical backreaction computed via the Thermofield dynamics approach in the Poincare patch of de Sitter spacetime. The resulting bulk equation takes the Whittaker form and we examine two distinct applications. At leading order, the co-moving curvature perturbations are shown to match a constant-roll model in the frozen attractor regime, corresponding to a UV enhancement of the spectrum with $n_S \sim 2$. This blue tilt arises only for modes exiting the horizon during a transient late-time phase of inflation and therefore does not affect perturbations in the CMB scale. In the holographic context, we compute the CFT two-point function at the future boundary, and away from it we construct the flow-equation of the dual QFT that matches the beta-function of the Sp(N ) model in three dimensions.

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Antonis Kalogirou. 2026-01-22. The thermal backreaction of a scalar field in de Sitter spacetime. II. Spectrum enhancement and holography. https://arxiv.org/abs/2601.15878

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