The exact mass gap of the O(N) σ-model for arbitrary N >= 3 in d = 2
Abstract
Starting from the exact S-matrix of the O(N) model we derive an integral equation, which determines the free energy as the function of the chemical potential coupled to a Noether charge. For N = 3 and 4 the equation agrees with that obtained earlier by Polyakov and Wiegmann with Bethe Ansatz for the related fermionic models. Using a method discussed in a recent paper by M. Maggiore and the authors, this integral equation predicts for the mass gap m = (8/e)1/(N-2) × [1/Γ (1 + 1/(N - 2))] ΛMS.
On leave of absence from Institute for Theoretical Physics, Eötvös University, H-1088 Budapest 8, Hungary.- Publication:
-
Physics Letters B
- Pub Date:
- August 1990
- DOI:
- 10.1016/0370-2693(90)90686-Z
- Bibcode:
- 1990PhLB..245..529H