Probing the inflationary particle content: extra spin-2 field
  We study how inflationary observables associated with primordial tensor modes
are affected by coupling the minimal field content with an extra spin-2
particle during inflation. We work with a model that is ghost-free at the fully
non-linear level and show how the new degrees of freedom modify standard
consistency relations for the tensor bispectrum. The extra interacting spin-2
field is necessarily massive and unitarity dictates its mass be in the $m
\gtrsim H$ range. Despite the fact that this bound selects a decaying solution
for the corresponding tensor mode, cosmological correlators still carry the
imprints of such "fossil" fields. Remarkably, fossil(s) of spin $\geq 1$
generate distinctive anisotropies in observables such as the tensor power
spectrum. We show how this plays out in our set-up.
