Correlators from Amplitubes

TL;DR

This paper extends the amplitube approach from wavefunction coefficients to full correlation functions in cosmology, revealing a simpler structure with many vanishing terms and no relative minus signs.

Contribution

It introduces a novel amplitube expansion for correlation functions, uncovering hidden simplicity and differences from wavefunction coefficients.

Findings

Many vanishing contributions in correlator amplitube expansion

Correlation functions lack relative minus signs between terms

Simpler structure of correlation functions compared to wavefunction coefficients

Abstract

Recently, the wavefunction coefficients for conformally coupled scalars in an FRW cosmology have been presented as a sum over amplitude-like functions known as {\it amplitubes}. In this work we extend this analysis to full {\it correlation functions}. Remarkably, the amplitube expansion of the correlator exhibits many vanishing contributions that are otherwise present in the expansion of the wavefunction. Moreover, while the wavefunction coefficients suffer from relative minus signs between terms, the surviving terms in correlation function do not. These observations point to a hidden simplicity in the structure of the correlation function compared to that of the wavefunction coefficient.