The trispectrum in ghost inflation
  We calculate the trispectrum in ghost inflation where both the contact
diagram and scale-exchange diagram are taken into account. The shape of
trispectrum is discussed carefully and we find that the local form is absent in
ghost inflation. In general, for the non-local shape trispectrum there are not
analogous parameters to $\tau_{NL}^{loc.}$ and $g_{NL}^{loc.}$ which can
completely characterize the size of local form trispectrum.
