Bogoliubov Quasiparticle Excitations in the Two-Dimensional t-J Model
  Using a proposed numerical technique for calculating anomalous Green's functions characteristic of superconductivity, we show that the low-lying excitations in a wide parameter and doping region of the two-dimensional $t$$-$$J$ model are well described by the picture of dressed Bogoliubov quasiparticles in the BCS pairing theory. The pairing occurs predominantly in $d_{x^2-y^2}$-wave channel and the energy gap has a size $\Delta_d$$\simeq$$0.15J$$-0.27J$ between quarter and half fillings. Opening of the superconducting gap in the photoemission and inverse-photoemission spectrum is demonstrated. 
Y. Ohta, T. Shimozato, R. Eder, and S. Maekawa (Dept. of Appl. Phys.,   Nagoya Univ., Nagoya 464-01, Japan)