  We consider a 2D electron system on a square lattice with hopping beyond
nearest neighbors. The existence of the quantum critical point associated with
an electronic topological transition in the noninteracting system results in
density wave (DW) and high temperature d-wave superconducting (dSC)
instabilities in the presence of an exchange interaction J. We analyse
different
  DW ordering such as isotropic Spin DW (SDW), d-wave SDW, isotropic Charge DW
(CDW) and d-wave CDW. The coexistence of dSC and SDW orders leads necessary to
the existence of a third order which is a pi triplet superconducting (PTS)
order. A new phase diagram with a mixed phase of SDW, dSC and PTS order is
found. The theory is applied to high-Tc cuprates.
