Searches for other vacua II: A new Higgstory at the cosmological
  collider
  The detection of an oscillating pattern in the bispectrum of density
perturbations could suggest the existence of a high-energy second minimum in
the Higgs potential. If the Higgs field resided in this new minimum during
inflation and was brought back to the electroweak vacuum by thermal corrections
during reheating, the coupling of Standard Model particles to the inflaton
would leave its imprint on the bispectrum. We focus on the fermions, whose
dispersion relation can be modified by the coupling to the inflaton, leading to
an enhanced particle production during inflation even if their mass during
inflation is larger than the Hubble scale. This results in a large non-analytic
contribution to non-Gaussianities, with an amplitude $f_{\rm NL}$ as large as
$100$ in the squeezed limit, potentially detectable in future 21-cm surveys.
Measuring the contributions from two fermions would allow us to compute the
ratio of their masses, and to ascribe the origin of the signal to a new Higgs
minimum. Such a discovery would be a tremendous step towards understanding the
vacuum instability of the Higgs potential, and could have fascinating
implications for anthropic considerations.
