Twisted XXZ even-chain norm conjecture

Let $|\Psi^{(2n)}\rangle$ be the normalized ground-state vector of the twisted XXZ chain with $2n$ sites, let

$$\mathcal N_{2n}^2=\langle\Psi^{(2n)}|\Psi^{(2n)}\rangle,$$

and let $A_n$ be the number of alternating-sign $n\times n$ matrices. The twisted XXZ even-chain norm conjecture. The squared norm is

$$\mathcal N_{2n}^2=\frac{2\cdot5\cdots(3n-1)}{1\cdot4\cdots(3n-2)}A_n^2.$$

The formula is presented as an analogue of an earlier periodic-chain conjecture and remains unproved in the supplied text.