Cosmological Particle Production and Pairwise Hotspots on the CMB
  Heavy particles with masses much bigger than the inflationary Hubble scale
$H_*$, can get non-adiabatically pair produced during inflation through their
couplings to the inflaton. If such couplings give rise to time-dependent masses
for the heavy particles, then following their production, the heavy particles
modify the curvature perturbation around their locations in a time-dependent
and scale non-invariant manner. This results into a non-trivial spatial profile
of the curvature perturbation that is preserved on superhorizon scales and
eventually generates localized hot or cold spots on the CMB. We explore this
phenomenon by studying the inflationary production of heavy scalars and derive
the final temperature profile of the spots on the CMB by taking into account
the subhorizon evolution, focusing in particular on the parameter space where
pairwise hot spots (PHS) arise. When the heavy scalar has an $\mathcal{O}(1)$
coupling to the inflaton, we show that for an idealized situation where the
dominant background to the PHS signal comes from the standard CMB fluctuations
themselves, a simple position space search based on applying a temperature cut,
can be sensitive to heavy particle masses $M_0/H_*\sim\mathcal{O}(100)$. The
corresponding PHS signal also modifies the CMB power spectra and bispectra,
although the corrections are below (outside) the sensitivity of current
measurements (searches).
