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, [Formula: see text] with Δ 0 , the spin gap at 0K; x, the hole doping concentration and α, a constant.