We consider the scaling limit of the two-dimensional q-state Potts model for $q\leq 4$. We use the exact scattering theory proposed by Chim and Zamolodchikov to determine the one and two-kink form factors of the energy, order and disorder operators in the model. Correlation functions and universal combinations of critical amplitudes are then computed within the two-kink approximation in the form factor approach. Very good agreement is found whenever comparison with exact results is possible. We finally consider the limit $q\to 1$ which is related to the isotropic percolation problem. Although this case presents a serious technical difficulty, we predict a value close to 74 for the ratio of the mean cluster size amplitudes above and below the percolation threshold. Previous estimates for this quantity range from 14 to 220.
|Titolo:||Universal amplitude ratios in the two-dimensional q-state Potts model and percolation from quantum field theory|
|Autori:||DELFINO G; J. CARDY|
|Data di pubblicazione:||1998|
|Digital Object Identifier (DOI):||10.1016/S0550-3213(98)00144-8|
|Appare nelle tipologie:||1.1 Journal article|