Large trispectrum in two-field slow-roll inflation
  We calculate the conditions required to produce a large local trispectrum
during two-field slow-roll inflation. This is done by extending and simplifying
the 'heatmap' approach developed by Byrnes et al. The conditions required to
generate a large trispectrum are broadly the same as those that can produce a
large bispectrum. We derive a simple relation between tauNL and fNL for models
with separable potentials, and furthermore show that gNL and tauNL can be
related in specific circumstances. Additionally, we interpret the heatmaps
dynamically, showing how they can be used as qualitative tools to understand
the evolution of non-Gaussianity during inflation. We also show how fNL, tauNL
and gNL are sourced by generic shapes in the inflationary potential, namely
ridges, valleys and inflection points.
