  We analyze the spectrum of the N=(2,2) supersymmetric Landau-Ginzburg theory
in two dimensions with superpotential W=X^{n+2}-lambda X^2. We find the full
BPS spectrum of this theory by exploiting the direct connection between the UV
and IR limits of the theory. The computation utilizes results from the
Picard-Lefschetz theory of singularities and its extension to boundary
singularities. The additional fact that this theory is integrable requires that
the BPS states do not close under scattering. This observation fixes the masses
of non-BPS states as well.
