Search Visibility Gap: Pedagogical Wigner–Eckart Dominates, Primary Sources Sparse — E8 Intelligence Research

FINDING: Search results are dominated by pedagogical videos on the standard Wigner–Eckart theorem; the specific arXiv paper (2007.03539) on topological sector finite-size corrections is not retrieved. The only relevant primary source is an arXiv abstract on Wigner–Eckart for finite magnetic groups (0911.0276v1). | MATH: Standard Wigner–Eckart: \( j' m' | T⁽ᵏ⁾_q | j m = j k; m q | j' m' { j' \| T⁽ᵏ⁾ \| j }{√2j'+1}\) — Clebsch–Gordan coefficients \( j k; m q | j' m' \) encode angular momentum addition; reduced matrix element \( j' \| T⁽ᵏ⁾ \| j \) is independent of \(m, m', q\). For magnetic groups: symmetry-adapted basis requires projective representations, modifying the CG coefficients by phase factors from the magnetic point group's cohomology. | CONNECTION: The CG coefficients themselves are algebraic roots of unity and relate to \(3j\)-symbols; for \(j=1\) they involve ratios \(√2/3, Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com