Phase Information in Cosmological Collider Signals
  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.
