Author(s): Yuqi Wang, Wei-Hai Fang, and Zhendong Li The $GW$ approximation is a cornerstone of many-body perturbation theory for computing single-particle excitations, yet it can fail qualitatively in strongly correlated systems where the single-reference picture becomes inadequate. To overcome this limitation, we develop a diagrammatic route to mult… [Phys. Rev. Lett. 137, 176402] Published Wed Oct 21, 2026