Pseudogap formation in an electronic system with d-wave attraction at low density

On the basis of an electronic model with separable attractive interaction, the precursors at high temperature and strong coupling of the d-wave superconducting state are investigated in the one-particle spectral function $A(\mathbf{k},\omega )$ and the total density of states $\rho \left(\omega \right),$ with the use of the self-consistent t-matrix approximation. In the low-density region, it is found that a gaplike structure at the Fermi level appears in $A(\mathbf{k},\omega )$ and $\rho \left(\omega \right)$ above the superconducting transition temperature. It is shown that the pseudogap energy scale is determined by the binding energy of the Cooper pair.