We discuss two different cases of strongly correlated fermions statistics. The first of them is the non-Fermi liquid (NFL) case, i. e. , that of fermions with exclusion of doubly occupancy of quasimomentum states \ (\ k\\) with opposite spins (\ (\) ). The second is the statistical spin liquid (SSL) case, in which the fermion spins hop around and mix with the holes (unoccupied) states. For both cases, we calculate the system entropy and the corresponding statistical distribution function, analyzed for a two-dimensional square-lattice filling \ (n 0, 1\) and relative temperature \ (k_ B T/|t|\), where \ (t 0\) is the nearest neighbor hopping integral. We are particularly interested in the situation when the system of itinerant fermions reduce to the Mott-insulator state for the half-filled band (\ (n 1\) ). This limiting situation signals a qualitative difference between the present SSL statistics and that of uncorrelated fermions representing a normal Fermi-liquid state. Abstract Published by the Jagiellonian University 2026 authors
Spałek et al. (Fri,) studied this question.