Correlation lengths and E8 mass spectrum of the dilute A3 lattice model Original Research Article

The exact perturbation approach is used to derive the elementary correlation lengths ξi and related mass gaps mi of the two-dimensional dilute AL lattice model in regimes 1 and 2 for L odd from the Bethe ansatz solution. In regime 2 the A3 model is the E8 lattice realisation of the two-dimensional Ising model in a magnetic field at T = Tc The calculations for the A3 model in regime 2 start from the eight thermodynamically significant string types found in previous numerical studies. These string types are seen to be consistent in the ordered high field limit. The eight masses obtained reduce with the approach to criticality to the ES masses predicted by Zamolodchikov, thus providing a further direct lattice determination of the Es mass spectrum.