Establish the unlocked-phase cross-ratio conjecture

Establish the thermodynamic identity $\mathcal R_\alpha^{(\times)}=2^{\alpha-1}$ for the normalization-free free/fixed cross-ratio throughout the unlocked phase $0<\alpha<4$.

Background

The second normalization-free ratio is independent of the character central-limit hypothesis controlling Rα(η)\mathcal R_\alpha^{(\eta)}. Exact values are known at α=1\alpha=1 and α=2\alpha=2, while numerical and Pfaffian data support the proposed formula at additional indices.

The conjecture would imply an Rényi-index-independent entropy combination Δα(×)=−log⁡2\Delta_\alpha^{(\times)}=-\log 2 throughout the unlocked phase. The paper explicitly says that this behavior, especially near α=4\alpha=4, lacks an analytic proof.

References

We conjecture \begin{equation} _{\alpha}{(\times)}=2{\alpha-1}, \qquad 0<\alpha<4. \label{eq:S11-Rcross-conjecture} \end{equation}

— Classical Root Systems Reveal Defect-Junction Data in Stabilizer Renyi Entropy  (2609.27537 - Rajabpour, 23 Sep 2026) in Section S11, subsection “The second invariant”

The combined support, Pfaffian, Shannon-derivative, and finite-rank evidence motivates the unlocked-phase conjecture Eq.~eq:S11-Rcross-conjecture; its behavior arbitrarily close to $\alpha=4$ remains to be established analytically.

— Classical Root Systems Reveal Defect-Junction Data in Stabilizer Renyi Entropy  (2609.27537 - Rajabpour, 23 Sep 2026) in Section S11, final paragraph of “Thermodynamic status”