Four-Loop Perturbative Expansion for the Lattice $N$-Vector Model

Abstract

We compute the four-loop contributions to the $\beta$-function and the anomalous dimension of the field for the $O(N)$-invariant $N$-vector model. These results are used to compute the second analytic corrections to the correlation length and the general spin-$n$ susceptibility.

Comments: 29 pages, to appear in Nucl. Phys. B, latex, subeqnar, epsf styles needed, one figure, available also as postscript at http://www1.le.infn.it:8080/~caraccio/95.html