Upper critical field of high-T-c oxides: Evidence for 2e bose liquid

We measure and theoretically describe the upper critical field, H-c2(T), of BSCCO - 2212 crystals with T-c > 92 K by the use of the out-of-plane resistivity in magnetic fields (H perpendicular to ab) up to 15 T. The empirical procedure is proposed allowing vs to extrapolate the H-c2(T) curve up to H-c2 similar or equal to 230 T and T/T-c similar or equal to 0.35 which is independent of the choice of the R/R(N) ratio. We Sound that H-c2(T) does not follow the conventional theory with or without fluctuations and the magnetic scattering, but is consistent with the prediction based on the Bose-Einstein condensation of charged bosons formed above T-c. Our results together with several other measurements of H-c2 and with the heat capacity data provide an evidence for the possibility of 2e Bose liquid ground state of high-T-c oxides.