Starts 12 Nov 2026 16:00
Ends 12 Nov 2026 17:00
Central European Time
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HECAP Seminar by Arthur Poisson - de Sitter Momentum Space
Hybrid
Leonardo Building - Luigi Stasi Seminar Room and via Zoom
Abstract
The study of late time correlation functions on top of a de Sitter background is of prime interest in primordial cosmology. Due to the non-conservation of energy, their evaluation represent a significant technical challenge and their mathematical structure remains unclear. In this talk, I will propose a new direction to address both of these issues by introducing a frequency-momentum space representation arising from the decomposition into unitary irreducible representations of the space-time isometry group SO(1,d+1), which trades the familiar (d+1)-dimensional Fourier space for the Kontorovich-Lebedev-Fourier (KLF) space. At the non-perturbative level, I will show that the de Sitter Kallen-Lehman representation directly follows from the decomposition of the two-point function into KLF modes. At the perturbative level, I will present how this formalism get rids of the nested time integrals and allows us to simply evaluate some simple loop diagrams.