A rapidity-independent parameter in the star-triangle relation
arXiv:cond-mat/0108363
Abstract
The normalization factor in the star-triangle relation can be evaluated in a simple form by taking determinants. If we combine this with the rotation symmetries, then we can show that a certain simple quantity has to be independent of the rapidities. In this sense it is an invariant. We evaluate it for several particular models and find it is one for self-dual models, and is related to the modulus (or ) for the Ising, Kashiwara-Miwa and chiral Potts models.
18 pages