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 single-particle properties (i.e., energy spectra, spectral functions, density of states) [18,99]

The *COM* results have been analyzed in relation with
the ones obtained by:

- Numerical techniques (i.e., Exact diagonalization, Lanczos and quantum
Monte Carlo)
[100,101,52,102]
- Slave boson technique [103]

The temperature dependence of the density of states has been
calculated
[18] 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 [99]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.