De Sitter momentum space

06.03.2026 11:50 – 12:50

Quantum field theory in de Sitter space is notoriously difficult. In this talk, I will introduce a new momentum space adapted to de Sitter isometries that provides a natural language and allows us to bypass several difficulties usually encountered. This construction is based on diagonalizing the Casimir operator together with spatial translations, effectively trading the usual (d+1)-dimensional Fourier space for what we call the Kontorovich–Lebedev–Fourier (KLF) space. I will show practical advantages of this description: the quadratic dynamics provides a simple propagator analogous to flat space, and nested time integrals appearing in the computation of cosmological correlators turn into frequency-space integrals over meromorphic functions. I will also show how this construction naturally accommodates the contributions from principal and complementary series in the Källén-Lehmann spectral decomposition of composite operators.

Lieu

Bâtiment: Ecole de Physique

EP234

entrée libre