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arXiv · 2512.20706

Propagator positivity bounds for cosmological correlators

Mang Hei Gordon Lee·Scott Melville
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Abstract

Using unitarity and causality, we derive an infinite tower of two-sided positivity bounds on the effective field theory coefficients which describe the propagation of heavy fields on de Sitter spacetime. We design this EFT to describe propagators with the in-in boundary conditions that are relevant for cosmological correlators. Our positivity bounds therefore identify EFT correlators that can never emerge from a consistent underlying model of inflation. This implies non-trivial constraints on primordial non-Gaussianity; for instance the cosmological collider oscillations in the squeezed bispectrum from the exchange of a heavy scalar are tied to the shape of its EFT background.

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Mang Hei Gordon Lee, Scott Melville. 2025-12-23. Propagator positivity bounds for cosmological correlators. https://doi.org/10.1103/nh6r-x6nq

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