$1/N$ expansion in the Gross-Neveu model with arbitrary number of fermion multiplets

Two-dimensional massless four-fermion theory (1) is considered which includes, any number of fermionic multiplets in the leading order of $1/N$ expansion. The model is asymptotically free. At any value of the coupling constant the chiral invariance is dynamically broken and fermions get masses. For the case of two multiplets at least two different phases with massive fermions are shown to exist. Conditions are found under which the theory has no ghosts. Masses of boson states are calculated for the case of equal fermion masses.