On Cosmological Correlators at One Loop

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Hauptverfasser: Pimentel, Guilherme L., Westerdijk, Tom
Format: Preprint
Veröffentlicht: 2026
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author Pimentel, Guilherme L.
Westerdijk, Tom
author_facet Pimentel, Guilherme L.
Westerdijk, Tom
contents We study equal-time in-in correlators of massless scalar fields in flat space at one loop. Using the time-ordered decomposition of correlators together with a cosmological analogue of the Baikov representation, we systematically construct relatively simple loop integrals and make manifest why, in this setting, loop corrections to correlators are simpler than those of wavefunction coefficients. As benchmark examples, we analyse the bubble and triangle diagrams. The bubble exhibits a UV divergence that can be removed by a local counterterm, while the triangle yields a finite result, which we evaluate explicitly in terms of dilogarithms using an integral transform for the Laplacian Green's function. We classify the kinematic singularities of these diagrams using Landau analysis, identifying novel types of singular behaviour, and validate this analysis against the explicit results. Finally, we derive a factorisation property of one-loop cosmological correlators at singular kinematics, relating them to flat-space loop amplitudes and lower-point tree-level correlators.
format Preprint
id arxiv_https___arxiv_org_abs_2601_00952
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On Cosmological Correlators at One Loop
Pimentel, Guilherme L.
Westerdijk, Tom
High Energy Physics - Theory
Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
We study equal-time in-in correlators of massless scalar fields in flat space at one loop. Using the time-ordered decomposition of correlators together with a cosmological analogue of the Baikov representation, we systematically construct relatively simple loop integrals and make manifest why, in this setting, loop corrections to correlators are simpler than those of wavefunction coefficients. As benchmark examples, we analyse the bubble and triangle diagrams. The bubble exhibits a UV divergence that can be removed by a local counterterm, while the triangle yields a finite result, which we evaluate explicitly in terms of dilogarithms using an integral transform for the Laplacian Green's function. We classify the kinematic singularities of these diagrams using Landau analysis, identifying novel types of singular behaviour, and validate this analysis against the explicit results. Finally, we derive a factorisation property of one-loop cosmological correlators at singular kinematics, relating them to flat-space loop amplitudes and lower-point tree-level correlators.
title On Cosmological Correlators at One Loop
topic High Energy Physics - Theory
Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2601.00952