The replica conjecture for the non-Hermitian R-transform of a unitary sum

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Let A\mathbf{A} and B\mathbf{B} be two large independent random matrices, and let U\mathbf{U} be a Haar-distributed unitary random matrix. For large z∈Cz\in\mathbb{C} or large ω∈R\omega\in\mathbb{R}, let GA(ω,z)\mathcal{G}_{\mathbf{A}}(\omega,z) denote the matrix-valued transform used in the paper, and let g1(ω,z)\mathfrak{g}_1(\omega,z) and g2(ω,z)\mathfrak{g}_2(\omega,z) be its scalar components. Replica conjecture. One expects

EU ⁣[GA+UBU∗(ω,z)]=GA ⁣(ω−R1,B(g1(ω,z),g2(ω,z)), z−R2,B(g1(ω,z),g2(ω,z))).\mathbb{E}_{\mathbf{U}}\!\left[\mathcal{G}_{\mathbf{A}+\mathbf{U}\mathbf{B}\mathbf{U}^*}(\omega,z)\right] = \mathcal{G}_{\mathbf{A}}\!\left(\omega-\mathcal{R}_{1,\mathbf{B}}(\mathfrak{g}_1(\omega,z),\mathfrak{g}_2(\omega,z)),\,z-\mathcal{R}_{2,\mathbf{B}}(\mathfrak{g}_1(\omega,z),\mathfrak{g}_2(\omega,z))\right).

This identity is expected to admit an analytic continuation to all (ω,z)(\omega,z), with appropriate choices of branches of the multivalued extensions R1~\widetilde{\mathcal{R}_1} and R2~\widetilde{\mathcal{R}_2}. The conjecture is the paper's main replica-method prediction for addition of large independent non-Hermitian random matrices under unitary conjugation; the supplied text gives no evidence of resolution.

References

Primary source

Pierre Bousseyroux and Marc Potters, “R-transforms for non-Hermitian matrices: a spherical integral approach”, arXiv:2601.09360 (2026).

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