Warm DBI Inflation
  We propose a warm inflationary model in the context of relativistic D-brane
inflation in a warped throat, which has Dirac-Born-Infeld (DBI) kinetic term
and is coupled to radiation through a dissipation term. The perturbation
freezes at the sound horizon and the power spectrum is determined by a
combination of the dissipative parameter and the sound speed parameter. The
thermal dissipation ameliorates the {\it eta} problem and softens theoretical
constraints from the extra-dimensional volume and from observational bounds on
the tensor-to-scalar ratio. The warm DBI model can lead to appreciable
non-Gaussianity of the equilateral type. As a phenomenological model, ignoring
compactification constraints, we show that large-field warm inflation models do
not necessarily yield a large tensor-to-scalar ratio.
