Electron momentum distribution of a single mobile hole in the t-J model
  We investigate the electron momentum distribution function (EMDF) for the two-dimensional t-J model. The results are based on the self-consistent Born approximation (SCBA) for the self-energy and the wave function. In the Ising limit of the model we give the results in a closed form, in the Heisenberg limit the results are obtained numerically. An anomalous momentum dependence of EMDF is found and the anomaly is in the lowest order in number of magnons expressed analitycally. We interpret the anomaly as a fingerprint of an emerging large Fermi surface coexisting with hole pockets. 
Anton Ramsak (1 and 2) and Igor Sega (1) ((1) J. Stefan Institute,   Ljubljana, Slovenia, (2) Faculty of Mathematics and Phy...