Finance

Physics

De Sitter universe

Hypergeometric function

Pure mathematics

Mathematics

Mathematical physics

Boundary (topology)

Fourier transform

Operating system

Anti-de Sitter space

Dielectric

Mathematical analysis

Position and momentum space

Economics

Mellin transform

De Sitter space

Space (punctuation)

Theoretical physics

Computer science

Conformal field theory

Massless particle

Quantum mechanics

Conformal map

Correlation function (quantum field theory)

Momentum (technical analysis)

Universe

Journal of High Energy Physics

We propose a Mellin space approach to the evaluation of late-time momentum-space correlation functions of quantum fields in (d + 1)-dimensional de Sitter space. The Mellin-Barnes representation makes manifest the analytic structure of late-time correlators and, more generally, provides a convenient general d framework for the study of conformal correlators in momentum space. In this work we focus on tree-level correlation functions of general scalars as a prototype, including n-point contact diagrams and 4-point exchanges. For generic scalars, both the contact and exchange diagrams are given by (generalised) Hypergeometric functions, which reduce to existing expressions available in the literature for d = 3 and external scalars which are either simultaneously conformally coupled or massless. This approach can also be used for the perturbative bulk evaluation of momentum space boundary correlators in (d + 1)-dimensional anti-de Sitter space (Witten diagrams).

A Mellin space approach to cosmological correlators