Integrable perturbations of Z _{N} parafermion models and the O(3) sigma model
Abstract
A system of thermodynamic Bethe ansatz equations is suggested for integrable perturbation of the Z _{N} parafermion CFT model by the basic parafermion field. Several checks are performed to justify the relevance of the system suggested. In the limit N→∞ we obtain an infinite TBA system describing the finite size effects in the nonlinear O(3) sigma model. Certain modified Z _{z} parafermion perturbations are introduced, which are argued to converge at N→∞ to the O(3) sigma model with the θ term. For θ= π we suggest for every N a massless TBA system describing the interpolating renormalizaition group flow from the ultraviolet Z _{N} fixed point to the infrared fixed point, which turns out to be the minimal unitary CFT model M_{N+1}.
 Publication:

Physics Letters B
 Pub Date:
 November 1991
 DOI:
 10.1016/03702693(91)912832
 Bibcode:
 1991PhLB..271...91F