Doping dependence of bose condensation energy in high Tc cuprates

The doping dependence of the bose condensation energy is investigated by using our SU(2) holon-pair boson theory. It is shown that the bose condensation energy U results from the interplay between the charge and spin degrees of freedom and that the doping dependence of U at T = 0K is well fit by the relation, U ≈ αx²x²Δ0 ² with Δ0, the spin gap at 0K; x, the hole doping concentration and α, a constant.