A study of the t-J model by means of the COM is reported in Refs. [18,99]. In particular the following properties have been computed:
The COM results have been analyzed in relation with the ones obtained by:
The temperature dependence of the density of states has been calculated  in the COM by including dynamical contributions in the self-energy. A coherent peak at the Fermi level increases its intensity with decreasing temperature and splits into two peaks, corresponding to the electronic excitations from spin singlet and triplet states. This scenario is confirmed by the results of numerical simulation [100,101,52,102].
A calculation of the electronic states within a polar approximation has been performed by considering a five-component composite field. By doping, the energy spectrum changes from a half-zone structure at half filling to a flat band with a large Fermi surface at low doping and to usual band structure at higher doping.