TOPOLOGICAL CONTRIBUTIONS TO THE PARTITION-FUNCTION FOR 2D MASSIVE FERMIONS

We study the contribution of topologically non-trivial sectors to the vacuum functional Z(m) of a model of massive fermions in two dimension s. By using recent results on non-minimal correlation functions we can write Z(m) as a kind of sector expansion. In this series, the contrib ution of each sector is given by integrals of minimal correlation func tions evaluated in the massless theory. Finally we comment on the appl ication of our result to the analysis of some special cases. In partic ular we briefly show that Coleman's equivalence between the massive Th irring and sine-Gordon models is not affected when topology is taken i nto account.