  The recent discovery of an incipient charge density wave (CDW) instability
competing with superconductivity in a class of high temperature cuprate
superconductors has brought the role of charge order in the cuprate phase
diagram under renewed focus. Here we take a mean field (Q = 2pi/3,2pi/3)
bi-axial CDW state and calculate the Fermi surface topology and the resulting
Hall and Seebeck coefficients as a function of temperature and hole doping. We
show that, in the appropriate doping ranges where the low temperature state (in
the absence of superconductivity) is a bi-directional CDW, the Fermi surface
consists of electron pockets, resulting in the Hall and Seebeck coefficients
becoming negative at low temperatures as seen in experiments.
