Partially Massless Fields During Inflation
  The representation theory of de Sitter space allows for a category of
partially massless particles which have no flat space analog, but could have
existed during inflation. We study the couplings of these exotic particles to
inflationary perturbations and determine the resulting signatures in
cosmological correlators. When inflationary perturbations interact through the
exchange of these fields, their correlation functions inherit scalings that
cannot be mimicked by extra massive fields. We discuss in detail the squeezed
limit of the tensor-scalar-scalar bispectrum, and show that certain partially
massless fields can violate the tensor consistency relation of single-field
inflation. We also consider the collapsed limit of the scalar trispectrum, and
find that the exchange of partially massless fields enhances its magnitude,
while giving no contribution to the scalar bispectrum. These characteristic
signatures provide clean detection channels for partially massless fields
during inflation.
