  We analyze the long range Ising spin glass in a transverse field by using
Grassmann variables in a field theory where the spin operators are represented
by bilinear combinations of fermionic fields. We compare the results of two
fermionic models. In the four state (4S)-model the diagonal Sz operator has two
vanishing eigenvalues, that are suppressed by a restraint in the two states
(2S)-model. Within a replica symmetric theory and in the static approximation
we obtain similar results for both models.
