Key points are not available for this paper at this time.
A systematic solution of a model for copper oxides reveals a line of transitions T{0ex{0ex}=0ex{0ex}T} (x) for x, the doping away from half filling less than a critical value, to a phase with broken time reversal and rotational symmetry. The single-particle spectrum in this phase is calculated to have a gap (kₗa/) -cos (kₘa/) ^2. The properties in this phase are compared to the properties of the so-called ``pseudogap phase'' of the copper oxides.
C. M. Varma (Mon,) studied this question.