APPLICABILITY OF THE STANDARD RENORMALIZED FIELD-THEORY TO THE STRONG-COUPLING REGIME FOR THE DOMB-JOYCE MODEL

We present a field theoretic analysis of high-precision Monte Carlo da ta for the Domb-Joyce model. This analysis shows the ability of the st andard formalism to describe the data. In the Domb-Joyce model of a po lymer chain the repulsion between two segments at the same point is va ried between zero (random walk) up to infinity (self avoiding walk). T o increase the excluded volume we even include a repulsion between seg ments at neighbor points. The data for the end-to-end distance, the ra dius of gyration and the partition function clearly shows the existenc e of two branches of universal behavior, corresponding to weak or stro ng excluded volume. The nonuniversal parameters of the renormalized th eory have to be considered as fitting parameters to one given quantity (We have chosen the end-to-end distance). Given these nonuniversal pa rameters, we can predict the variation of all other measured quantitie s. Good agreement with the MC data is found for all data, including th e strong coupling branch. We conclude, in contrast to some claims in t he literature, that the standard formalism of the renormalized field t heory can be used even for renormalized couplings greater than the fix ed point value (strong coupling branch).