Hole pockets in the doped 2D Hubbard model

The electronic momentum distributionn(k) of the two dimensional Hubbard model is studied for different values of the couplingU/t, electronic density n, and temperature, using quantum Monte Carlo techniques. A detailed analysis of the data on 8 × 8 clusters shows that features consistent with hole pockets at momentak = (±/2,±/2) appear as the system is doped away from half-filling. Our results are consistent with recent experimental data for the cuprates discussed by Aebi et al. (Phys. Rev. Lett. 72, 5757 (1994)). In the range of couplings studied, the depth of the pockets is maximum at n 0.9,and it increases with decreasing temperature. The apparent absence of hole pockets in previous numerical studies of this model is explained.