Using the equivalence with a derivative-coupling model, mass perturbation in the Thirring model is investigated. We show that, for 4π(2- √3 )<${\beta }^2$<8π all ultraviolet divergences cancel. Finite composite operators are constructed in this range. Ward identities and equations of motion are discussed.

• Received 21 November 1985

DOI:https://doi.org/10.1103/PhysRevD.34.504