J/t$ and a broad incoherent part that has a width of about $6-7t$. The QP band bottom corresponds to the momenta ${\bf k}_1=(\pm \pi /2,\pm \pi
/2)$ . Similar results were obtained for the Emery model [@Rei; @kab]. The presence of a great incoherent part and small intensity of QP peak indicate, that bare holes are rather poor elementary excitations even for ${\bf k}$ close to ${\bf k}_1$ .

In order to investigate the hole motion in the $t-J$ model one usually decouple the hole operator into a spinless fermion and an antiferromagnetic magnon operator. As a result the zero approximation corresponds to the dispersionless band with zero energy of the hole. The hopping of the particle appears only due to the fermion-magnon scattering which is treated by the usual perturbation method in ${\bf k}$-space. For this reason we think that in this approach the resulting quasiparticle pole in the fermion Green’s function takes into account mainly a polaron of a large radius. The close situation takes place in the usual treatment of a hole motion in the effective three-band model [@Rei; @kab; @Oleg1] and the Kondo-lattice model [@Prel], when one starts from a bare hole, not from a magnetic 