A new branch of inflationary speed limits
  We present a new mechanism for inflation which exhibits a speed limit on
scalar motion, generating accelerated expansion even on a steep potential. This
arises from explicitly integrating out the short modes of additional fields
coupled to the inflaton $\phi$ via a dimension six operator, yielding an
expression for the effective action which includes a nontrivial (logarithmic)
function of $(\partial\phi)^2$. The speed limit appears at the branch cut of
this logarithm arising in a large flavor expansion, similarly to the square
root branch cut in DBI inflation arising in a large color expansion. Finally,
we describe observational constraints on the parameters of this model.
