F. Ravanini et al., INTEGRABLE PERTURBATIONS OF CFT WITH COMPLEX PARAMETER - THE M(3 5) MODEL AND ITS GENERALIZATIONS/, International journal of modern physics A, 11(4), 1996, pp. 677-697
By using the thermodynamic Bethe ansatz, approach, we give evidence of
the existence of both massive and massless behaviors for the phi(2,1)
perturbation of the M(3,5) nonunitary minimal model, thus resolving a
pparent contradictions in the previous literature. The two behaviors c
orrespond to changing the perturbing bare coupling constant from real
values to imaginary ones. Generalizations of this picture to the whole
class of nonunitary minimal models M(p,2p+/-1), perturbed by their fe
ast relevant operator, lead to a cascade of flows similar to that of u
nitary minimal models perturbed by phi(1,3). Various aspects and gener
alizations of this phenomenon and the links with the Izergin-Korepin m
odel are discussed.