  The proton decay modes $p\to K^0 e^+$ and $p\to K^0 \mu^+$ may be visible in
certain supersymmetric theories, and if seen would provide evidence for new
flavor physics at extremely short distances. These decay modes can arise from
the dimension five operator $(Q_1Q_1Q_2L_{1,2})$, where $Q_i$ and $L_i$ are
${i^{th}}$ generation quark and lepton superfields respectively. Such an
operator is not generated at observable levels due to gauge or Higgs boson
exchange in a minimal GUT. However in theories that explain the fermion mass
hierarchy, it may be generated at the Planck scale with a strength such that
the decays $p\to K^0 \ell^+$ are both compatible with the proton lifetime and
visible at Super-Kamiokande. Observable proton decay can even occur in theories
without unification.
