 
Summary: Nuclear Physics B 660 [FS] (2003) 579606
www.elsevier.com/locate/npe
Excited TBA equations II: massless flow from
tricritical to critical Ising model
Paul A. Pearce a
, Leung Chim a,1
, Changrim Ahn b
a Department of Mathematics and Statistics, University of Melbourne, Parkville,
Victoria 3010, Australia
b Department of Physics, Ewha Womans University, Seoul 120750, South Korea
Received 14 February 2003; accepted 24 March 2003
Abstract
We consider the massless tricritical Ising model M(4,5) perturbed by the thermal operator
1,3 in a cylindrical geometry and apply integrable boundary conditions, labelled by the Kac
labels (r,s), that are natural offcritical perturbations of known conformal boundary conditions.
We derive massless thermodynamic Bethe ansatz (TBA) equations for all excitations by solving,
in the continuum scaling limit, the TBA functional equation satisfied by the doublerow transfer
matrices of the A4 lattice model of Andrews, Baxter and Forrester (ABF) in Regime IV. The resulting
TBA equations describe the massless renormalization group flow from the tricritical to critical Ising
model. As in the massive case of Part I, the excitations are completely classified in terms of (m,n)
