Beauty is Distractive: Particle production during multifield inflation
  We consider a two-dimensional model of inflation, where the inflationary
trajectory is "deformed" by a grazing encounter with an Extra Species/Symmetry
Point (ESP) after the observable cosmological scales have left the Hubble
radius. The encounter entails a sudden production of particles, whose
backreaction causes a bending of the trajectory and a temporary decrease in
speed, both of which are sensitive to initial conditions. This "modulated"
effect leads to an additional contribution to the curvature perturbation, which
can be dominant if the encounter is close. We compute associated
non-Gaussianities, the bispectrum and its scale dependence as well as the
trispectrum, which are potentially detectable in many cases. In addition, we
consider a direct modulation of the coupling to the light field at the ESP via
a modulaton field, a mixed scenario whereby the modulaton is identified with a
second inflaton, and an extended Extra Species Locus (ESL); all of these
scenarios lead to similar additional contributions to observables. We conclude
that inflaton interactions throughout inflation are strongly constrained if
primordial non-Gaussianities remain unobserved in current experiments such as
PLANCK. If they are observed, an ESP encounter leaves additional signatures on
smaller scales which may be used to identify the model.
