Phase Information in Cosmological Collider Signals

TL;DR

This paper explores the phase of oscillating signals in cosmological collider physics, revealing new insights into heavy particle properties during inflation through analytical and measurement techniques.

Contribution

It introduces a method to define and measure the phase of cosmological collider signals, providing new information about particle spin and couplings beyond existing frequency and angular analyses.

Findings

Analytical results for nonlocal signals from 1-loop processes

Phase measurement can distinguish particle properties

Enhanced understanding of inflationary particle interactions

Abstract

Massive particles produced during the cosmic inflation can imprint in the primordial non-Gaussianities as characteristic oscillating functions of various momentum ratios, known as cosmological collider signals. We initiate a study of the phase of the oscillating signals which can be unambiguously defined and measured. The phase can provide useful new information about the spin and the couplings of the intermediate heavy particles that cannot be obtained from the signal frequency and angular dependences alone. We also present new analytical results for full nonlocal signals from two typical 1-loop processes, enabling precise determination of the signal phase away from the squeezed limit.