From Amplitudes to Contact Cosmological Correlators

TL;DR

This paper develops a comprehensive method to derive scalar four-point cosmological correlators, or trispectra, using algebraic techniques and principles like symmetries and unitarity, extending the bootstrap approach.

Contribution

It introduces a general framework for constructing contact cosmological correlators from flat space amplitudes without assuming Lorentz invariance, broadening the bootstrap methodology.

Findings

Derived the most general scalar four-point correlator for contact interactions.

Extended the bootstrap approach to include non-Lorentz invariant amplitudes.

Connected flat space amplitudes with curved spacetime correlators in de Sitter.

Abstract

Our understanding of quantum correlators in cosmological spacetimes, including those that we can observe in cosmological surveys, has improved qualitatively in the past few years. Now we know many constraints that these objects must satisfy as consequences of general physical principles, such as symmetries, unitarity and locality. Using this new understanding, we derive the most general scalar four-point correlator, i.e., the trispectrum, to all orders in derivatives for manifestly local contact interactions. To obtain this result we use techniques from commutative algebra to write down all possible scalar four-particle amplitudes without assuming invariance under Lorentz boosts. We then input these amplitudes into a contact reconstruction formula that generates a contact cosmological correlator in de Sitter spacetime from a contact scalar or graviton amplitude. We also show how the same procedure can be used to derive higher-point contact cosmological correlators. Our results further extend the reach of the boostless cosmological bootstrap and build a new connection between flat and curved spacetime physics.