Bogoliubov-quasiparticle spectra of the effective d-wave model for cuprate superconductivity

An exact-diagonalization technique on finite-size clusters is used to study the ground state and excitation spectra of the two-dimensional effective-fermion model, a fictious model of hole quasiparticles derived from numerical studies of the two-dimensional t-J model at low doping. We show that then is actually a reasonable range of parameter values where the d(x)2(-y)2-wave pairing of holes occurs and the low-lying excitation can be described by the picture of Bogoliubov quasiparticles in the BCS pairing theory. The gap parameter of a size Delta(d) similar or equal to 0.13\V\ (where V is the attractive interaction between holes) is estimated ar low doping levels. The paired state gives way to the state of clustering of holes for some stronger attractions.