One-electron self energies and spectral functions for the t-J model in the large-N limit

Using a recently developed perturbative approach, which considers Hubbard operators as fundamental excitations, we have performed electronic self-energy and spectral function calculations for the $t-J$ model on the square lattice. We have found that the spectral functions along the Fermi surface are isotropic, even close to the critical doping where the $d$-density wave phase takes place. Fermi liquid behavior with scattering rate $sim omega^2$ and a finite quasiparticle weight $Z$ was obtained. $Z$ decreases with decreasing doping taking low values for low doping. Results are compared with other ones, analytical and numerical like slave-boson and Lanczos diagonalization finding agreement. We discuss our results in the light of recent $ARPES$ experiments in cuprates.