Hard hexagons: interfacial tension and correlation length

Functional equations are derived for the eigenvalues of the row-to-row transfer matrix of the generalised hard hexagon model. These equations are exact for a lattice with N columns and are solved in the limit N to infinity . The partition function per site is rederived without the previous analyticity assumptions. The authors are also able to calculate the interfacial tension and the correlation length; the associated critical exponents are mu = nu = nu '= 5 / 6 in agreement with the scaling relations.