Non-linear integral equation and finite volume spectrum of minimal models perturbed by Φ(1,3) Original Research Article

We describe an extension of the non-linear integral equation (NLIE) method to Virasoro minimal models perturbed by the relevant operator Φ(1,3). Along the way, we also complete our previous studies of the finite volume spectrum of sine-Gordon theory by considering the attractive regime and more specifically, breather states. For the minimal models, we examine the states with zero topological charge in detail, and give numerical comparison to TBA and TCS results. We think that the evidence presented strongly supports the validity of the NLIE description of perturbed minimal models.