Supersymmetric P(X,phi) and the Ghost Condensate
  We show how to construct supersymmetric actions for higher-derivative scalar
field theories of the form P(X,phi), within the context of d=4, N=1
supersymmetry. This construction is of general use, and is applied to write
supersymmetric versions of the Dirac-Born-Infeld action. Our principal
application of this formalism is to construct the supersymmetric extension of
the ghost condensate. This allows us to study the interplay between
supersymmetry, time-dependent backgrounds and violations of the null energy
condition.
