The open XXZ chain at $Δ=-1/2$ and totally-symmetric alternating sign matrices
The open XXZ spin chain with the anisotropy parameter $Δ=-\frac12$, diagonal boundary fields that depend on a parameter $x$, and finite length $N$ is studied. In a natural normalisation, the components of its ground-state vector are polynomials in $x$ with integer coefficients. It is shown that their sum is given by a generating function for the weighted enumeration of totally-symmetric alternating sign matrices with weights depending on $x$.
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