Bethe Ansatz and Rogers-Ramanujan-type identities

Abstract

The Rogers-Ramanujan identity for $\!\!\phantom{|}_1\psi_1$ $$ \sum_{n\in\mathbb{Z}} \frac{(a;q)_n}{(b;q)_n} z^n\;=\; \frac{(q,b/a,az,q/az;q)_\infty}{(b,q/a,z,b/az;q)_\infty} $$ can be classified as one related to the Bethe Ansatz for ``chain length $N=1$, ground state XXZ model with an arbitrary negative spin''.