The effect of fluctuations about the pi-flux mean field state for the undoped high-temperature superconductors is investigated. It is shown that fluctuations of the mean fields lead to a self-energy correction that doubles the band width of the fermi
on dispersion in the lowest order. The dynamical mass generation is associated with the self-energy effect due to the interaction mediated by the Lagrange multiplier field, which is introduced to impose the constraint on the fermions. A self-consistent picture about the mass generation and the prop- agation of the Lagrange multiplier field without damping is proposed. The antiferromagnetic long-range ordering is described without introducing an additional repulsive interaction. The theory suggests a natural framework to study spin disordered systems in which fermionic excitations are low-lying excitations.
Assuming antiferromagnetic orbital correlations to model the pseudogap state in the underdoped high-temperature superconductors, we study how this correlation is distinguished from the d-wave superconductivity correlation with including the finite-ra
nge antiferromagnetic correlation effect. In spite of the fact that both correlations have the same d-wave symmetry, the contributions from each correlation is clearly distinguished in the spectral weight and the density of states.
