  We discuss deep inelastic scattering at low $x$ as a critical phenomenon in
2+1 space-time dimensions. QCD (SU2) near the light cone becomes a critical
theory in the limit of $\lim x \to 0$ with a correlation mass $m(x) \propto
x^{\nu/2}$. We conjecture that the perturbative dipole wave function of the
virtual photon in the region $1/Q<x_{\bot}<1/m$ obeys correlation scaling $\Psi
\propto (x_{\bot})^{-(1+n)}$ before exponentially decaying for distances larger
than the inverse correlation mass. This behavior combined with an $x$
-independent dipole proton cross section gives a longitudinal structure
function which shows the dominant features of the experimental data. For SU3
QCD a similar second order phase transition is possible in the presence of
quark zero modes on the light cone.
