  We calculate the low energy effective action of massless and massive complex
linear superfields coupled to a massive U(1) vector multiplet. Our calculations
include superspace higher derivative corrections and therefore go beyond
previous results. Among the superspace higher derivatives we find that terms
which lead to a deformation of the auxiliary field potential and may break
supersymmetry are also generated. We show that the supersymmetry breaking vacua
can only be trusted if there exists a hierarchy between the higher order terms.
A renormalization group analysis shows that generically a hierarchy is not
generated by the quantum corrections.

High Energy Physics - Theory;High Energy Physics - Phenomenology