Phase Information in Cosmological Collider Signals

Understand

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.